WO2001052399A1 - Micro actuator with optimised deformable structure for disc storage and method for making same - Google Patents

Micro actuator with optimised deformable structure for disc storage and method for making same Download PDF

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Publication number
WO2001052399A1
WO2001052399A1 PCT/FR2000/003596 FR0003596W WO0152399A1 WO 2001052399 A1 WO2001052399 A1 WO 2001052399A1 FR 0003596 W FR0003596 W FR 0003596W WO 0152399 A1 WO0152399 A1 WO 0152399A1
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Prior art keywords
micro
actuator
layer
electrodes
deposited
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PCT/FR2000/003596
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French (fr)
Inventor
Jean-Pierre Lazzari
Jean Marc Lazzari
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Information Technology Dev Itd
Jean Marc Lazzari
Lazzari Jean Pierre
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Publication of WO2001052399A1 publication Critical patent/WO2001052399A1/en

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
    • G11B5/54—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head into or out of its operative position or across tracks
    • G11B5/55—Track change, selection or acquisition by displacement of the head
    • G11B5/5521—Track change, selection or acquisition by displacement of the head across disk tracks
    • G11B5/5552—Track change, selection or acquisition by displacement of the head across disk tracks using fine positioning means for track acquisition separate from the coarse (e.g. track changing) positioning means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N1/00—Electrostatic generators or motors using a solid moving electrostatic charge carrier
    • H02N1/002—Electrostatic motors
    • H02N1/006—Electrostatic motors of the gap-closing type
    • H02N1/008—Laterally driven motors, e.g. of the comb-drive type

Definitions

  • the subject of the present invention is a micro-actuator allowing the write-read head to follow recorded tracks of small size, on a hard disk, as well as its manufacturing process. 10 It finds applications in the field of hard disk memories, for mass storage of information.
  • a hard disk memory shown schematically in Figure 1 - * essentially comprises one or more disks (100) coated with an information carrier recording layer.
  • the magnetic writing and reading head (s) (103) are held in position by a suspension (102).
  • This suspension is mounted on an electromagnetic actuator (101), which by rotation positions the head (103) on the
  • the track (104) comprises zones carrying particular information intended to supply the head with signals which after processing will be sent to the actuator (101) in order to permanently center the head on the track (104).
  • the needs of computer science mean that the capacities of disk memories double on average every 18 months. To follow this strong growth in recording density, it is necessary to increase both the number of bits of information along the track what the person skilled in the art calls the linear density, and at the same time increase the 3 Q number of tracks, what those skilled in the art call the radial density.
  • FIG. 3 shows the diagram of a micro-actuator according to the prior art.
  • the movable part (300) which moves in the direction of the arrows (305).
  • This movable part is held by beams (301) which form a deformable parallelogram 5, connected at the other end to a fixed part (302).
  • These beams have a thickness of 30 to 40 ⁇ m, and a width of 4 to 5 ⁇ m. They are made of poly crystalline silicon, or sometimes electrolysed nickel.
  • the 0 separation between the combs is of the order of 3 ⁇ m.
  • the beams (301) have a slight flexibility in the direction of the arrows (305), and greater rigidity perpendicular to the plane of FIG. 3. All the shapes and structures of the micro-actuator are produced by MEM techniques, close to those of microelectronics. It should be noted that there are Q micro-actuators with rectilinear displacement or other micro-actuators with rotary displacements.
  • micro-actuators according to the structures described in FIG. 3, have many shortcomings:
  • the force of attraction between the combs is directly linked to the capacity between the combs.
  • the capacity thus formed is from 2 to 3 picofarads.
  • the energy developed by these micro-actuators is therefore very low.
  • Combs similar to those of micro-actuators are also used to make accelerometers.
  • the combs are protected by a watertight cap, which prevents dust, particles, rheumatism, can be interposed between the combs, which can disturb, or even block their movement.
  • the mobile part of the micro-actuator supports the head. It is therefore impossible according to this prior art, to seal the spaces between the combs to avoid external aggressions. We find this problem on two levels:
  • FIGS. 4A, 4B, and 4C a new structure, represented in FIGS. 4A, 4B, and 4C, was proposed by the patent application No. 9906430 of May 18, 1999. It is a deformable structure using a latex type elastomer (200) having a low Young's modulus, which under the influence of conductive layers (403) deposited in the plane of the micro-actuator, offset from each other, forming an electrostatic motor, which generates shear forces, deform the elastomer, producing a displacement of the upper plane of the micro-actuator (401), relative to the lower plane (402), as shown in FIGS. 4B and 4C, according to the electrical polarizations of the electrodes (403 ).
  • conductive layers 403
  • micro-actuators using the deformation of an elastomer, described above exhibit significant rigidity in the face of the deformation forces produced by the electrostatic motors.
  • the present invention adjustment aims to remedy these drawbacks, by providing a much more efficient electrostatic motor structure on the one hand, and a deformable structure based on elastomer offering lower rigidity in the direction of movement, on the other hand part, as well as the manufacturing process.
  • the invention provides a micro-actuator consisting of a deformable peripheral membrane made of an elastomer type material, separating two horizontal planes which hold vertical electrodes forming a capacitor.
  • the vertical electrodes are separated by a distance slightly greater than the displacement of the two horizontal planes, which means that the internal volume of the peripheral membrane is entirely occupied by the electrostatic motor, allowing it to generate very large forces, compared to those necessary deformation of the peripheral membrane.
  • the vertical electrodes are alternately attached to the upper horizontal plane, and to the lower horizontal plane. Their electrical polarization is such that the upper vertical electrodes are subjected to attractive forces relative to the lower vertical electrodes.
  • the micro-actuator according to the invention has great flexibility in the direction of movement, and high rigidity perpendicular to the plane of the micro-actuator, which allows it to absorb shocks, and even to absorb them.
  • the micro-actuator is very robust, and it is insensitive to particles, or to liquids.
  • the electrodes are in a volume totally isolated from the outside "by the peripheral membrane. It operates with voltages less than 100 Volts. It does not present any fatigue or hysteresis at a level which interferes with its operation. It is perfectly compatible with the processes currently used in the industry for assembling heads on their suspension. It presents no risk inside the disk memory in the face of the accumulation of particles. in the form of a homogeneous volume, which deforms according to the forces generated by the electrostatic motor.
  • the present invention relates to a micro-actuator for disk storage, and its manufacturing method, consisting of a set of vertical planar electrodes held alternately by an upper horizontal plane and by a lower horizontal plane. , the upper and lower horizontal planes, being held by a deformable peripheral membrane of the elastomer type, such as latex rubber, or silicone.
  • the electrical polarization of the vertical electrodes generates on each of them attractive forces relative to neighboring electrodes.
  • the deformable membrane which supports the upper and lower horizontal planes, seals the electrostatic motor, in relation to the environment external to the micro-actuator.
  • the lower horizontal plane of the micro-actuator is glued to the suspension, the upper horizontal plane of the micro-actuator supports the head.
  • the deformation of the peripheral membrane is very small compared to its height, which causes negligible hysteresis and fatigue.
  • the micro-actuator according to the invention has a capacity substantially greater than that of the micro-actuators according to the prior art.
  • the intensity of the forces generated by the electrostatic motor, whose electrodes move perpendicular to their plane, is significantly greater than that of the electrostatic motors of the prior art.
  • the peripheral membrane between the upper and lower horizontal planes has an optimized shape, so that it offers low resistance to deformation, in the direction of movement.
  • the micro-actuator has a central pivot, making it possible to pivot one relative to the other the upper and lower horizontal planes.
  • the micro-actuator according to any one of the structures described above has great vertical rigidity.
  • the deformable material due to its elasticity will absorb the impact, thereby preventing deterioration of the head, of the micro-actuator itself, or of the surface of the disc.
  • the displacement of the upper surface of the micro-actuator relative to its lower surface perhaps rectilinear, or rotary. This displacement can be measured by the variation in capacitance between neighboring electrodes. It is therefore possible to control the displacements of the micro-actuator, and thereby to get rid of possible non-linearities in the deformation of the peripheral membrane.
  • Figure 3 already described shows the structure of a micro-actuator according to a prior art
  • Figures 4 A, 4B, 4C, already described show a structure of a micro-actuator according to another prior art using the deformation of a material of the elastomer type, as well as the displacements of the planes (401) and (402) according to the polarity of the electrodes.
  • Figure 5 shows the section of a micro-actuator according to the invention.
  • Figure 6 shows the movement of the upper horizontal plane relative to the lower horizontal plane.
  • FIG. 7 shows a micro-actuator with circular displacement
  • FIG. 8 shows the process for producing the first group of vertical electrodes, attached to the lower plane.
  • FIG. 9 shows the process for producing the second group of vertical electrodes attached to the upper plane.
  • Figure 10 shows the process for producing the peripheral membrane as well as that of the upper plane.
  • FIG. 5 shows a first embodiment of the micro-actuator according to the invention.
  • the micro-actuator (200) according to a first embodiment of the invention, is in the form of a flat parallelepiped. Its width and length are substantially equal to those of the head (103) of Figure 2, which will be glued to its upper surface (502), while its lower surface (501) will be glued to the suspension (102) of the figure 2.
  • the thickness of the micro-actuator (200) is of the order of 30 ⁇ m to 100 ⁇ m, its length 1.25 mm, and its width 1 mm, when the head (103) is in the international format known as “pico "
  • the micro-actuator (200) appears from O
  • a deformable peripheral membrane made up of an elastomer, such as rubber, latex, or silicone, given by way of nonlimiting example.
  • the elasticity of a material is defined by its Young's modulus.
  • Nickel for example has a Young's modulus of 200 Giga Pascal (200Gpa).
  • the silicon superior to OOGpa.
  • the deformable elastomers (500) according to the invention have a Young's modulus of between 0.1 Mega Pascal (0.1 Mpa) and 100 Mpa.
  • Latex for example, has a Young's modulus between 4Mpa and 40Mpa.
  • Electrodes (503) and (505) are held by the upper plane (502), while the electrode (504) is held by the lower plane (501).
  • These electrodes once supplied with an electric voltage, form an electrostatic motor, which generates horizontal forces between each electrode, which are transmitted to the upper (502) and lower (501) rigid surfaces. These surfaces under the effect of the forces produced by the electrodes will move by slightly deforming the peripheral membrane (500).
  • Figure 6 shows an example of displacement.
  • the electrode (503) has the same polarity as the electrode (504), and that the electrode (504) is positively polarized with respect to the electrode 505), the electrode (505) will be attracted by l electrode (504), while the electrode (505) will not be subjected to any force relative to the electrode (504). It can therefore be seen, according to the invention, that according to the polarity of the upper electrodes relative to the lower electrodes, attractive forces between the upper and lower electrodes allow a displacement of the upper horizontal plane with respect to the lower horizontal plane.
  • the electrodes form a capacity of the order of 58pf, and generate a force of the order of 0.24 Newtons, for a voltage applied from 100 volts. If the maximum displacements sought between the upper plane (502) and the lower plane (501) are plus or minus 1 ⁇ m, then the separation between each electrode will be slightly greater than 1 ⁇ m, ie for example 1.5 ⁇ m.
  • the micro-actuator has a rectangular shape, with a rectilinear movement of the upper plane relative to the lower plane.
  • the shape of these parts of the membrane can advantageously be circular, or bent.
  • the micro-actuator is rotary.
  • the upper (502) and lower (501) planes have a circular shape.
  • the vertical electrodes are positioned along radii, and the outer peripheral membrane is circular, as shown in Figure 7 in plan view.
  • the center there is a pillar (700) which has a high rigidity in the plane, but a low rigidity in rotation.
  • the relative displacement of the two upper and lower surfaces is of the order of plus or minus one to two microns. If the thickness of the micro-actuator is 100 ⁇ m, the deformation of the peripheral membrane will only be a few percent.
  • the deformable materials according to the invention can accept elastic deformations of the order of 700 percent.
  • the deformations of the micro-actuator according to the invention are so small compared to what the material could collect, that they are not accompanied by either hysteresis or fatigue.
  • the micro-actuator (200) appears as a homogeneous whole, without micro-cavities. It is chemically inert, especially to liquid cleaning agents. It is very robust mechanically, especially in directions perpendicular to the plane of the surfaces (501) and (502). As the peripheral membrane connecting the two rigid planes of the micro-actuator, is made of deformable material, and as the micro-actuator is located between the suspension and the head, it constitutes a perfect shock absorber.
  • a first layer (801) called “sacrificial” is deposited, that is to say that will be eliminated thereafter.
  • This layer may be resin, or a polymer which can be dissolved in specific solvents, or a metallic or dielectric layer, known to those skilled in the art.
  • the sacrificial layer may have a thickness of a few microns.
  • a dielectric layer (501) is deposited which will constitute the lower surface of the micro-actuator.
  • This layer can be SiO 2, for example deposited according to low temperature processes, such as CVD or in English term “Chemical Vapor Deposition", process known to those skilled in the art.
  • the Si02 layer can have a thickness of the order of a few microns.
  • a conductive layer is deposited which, after photolithography and etching, techniques known from microelectronic processes, will constitute interconnections (802) connected to the voltage source, on which the first set of electrodes will be produced.
  • a layer of photosensitive resin (803) is then deposited from a few microns to a hundred microns thick.
  • a lithography is then carried out, followed by a revelation which will produce trenches (804) in the resin, these trenches opening down onto the conductors (802). These trenches will then be filled by electrolytic growth of a conductor, such as copper, or nickel for example. Other filling methods known to those skilled in the art, such as CVD for example, can also be used.
  • the resin is then removed, and a thin dielectric layer of the order of 1000 A ° is deposited on all the surfaces of the electrodes, such as SiO 2 for example. using a CVD deposit for example, so that the deposit is as homogeneous as possible. This layer will isolate the electrodes.
  • This layer (900) of FIG. 9 has a thickness greater than the height of the first set of electrodes (804).
  • a layer of Si02 (901) is deposited which will serve as an etching mask for the layer (900).
  • the layer (900) is etched in the form of trenches (902), the bottom of which will not touch the layer (501). The bottom may be around 5 ⁇ m above the layer (501).
  • a thin conductive layer (903) is then deposited which will line the inside of the trenches (902).
  • a conductive material such as nickel or copper will be grown by electrolysis inside the trenches (902) thus constituting a second set of electrodes which will be attached to the upper plane.
  • a CVD deposit to fill the trenches (902. On the surface (903), one then realizes a lithography, followed by an engraving to make the connections
  • connection (1000) of the electrodes of the upper plane, as shown in Figure 10.
  • the connections (1000) therefore connect the upper electrodes to the voltage source.
  • a lithography is then carried out followed by an etching of the layer of Si02 (901), in order to produce by selective etching, a trench
  • This trench can have a width of 10 to 100 ⁇ m for example. It has the shape of the peripheral membrane.
  • This trancjhée is then filled by the elastomer. They are in either liquid or pasty form, and polymerize by adding a polymerization liquid, associated with a temperature of the order of 50 ° C.
  • the elastomer can be deposited either with a squeegee or by centrifugation. A thick layer of SiO 2, several microns (1003), is deposited on the whole.
  • a lithography is then carried out on the layer of Si02 (1003), in order to produce numerous openings, which leave the layer of Si02 in the form of a grid (1002) open, up to the surface of the layer (900) .
  • the layer (900) is selectively etched by reactive ion etching, through the holes in the SiO 2 grid, then the layer (900) is completely eliminated by selective dissolution using a solvent. suitable, known to those skilled in the art.
  • the complete structure of the micro-actuator according to the invention is therefore obtained.
  • the upper electrodes are held by the rigid Si02 grid, made in the thick layer (1003), which is deposited on the peripheral membrane (1001).
  • the thick layer of Si02 in the form of grid (1003) a layer which may be a polymer, of ten microns thick, which will ensure the total sealing of the micro-actuator.
  • the first sacrificial layer (801) is eliminated in order to free each micro-actuator from the substrate (800) which held them during all the manufacturing stages.

Abstract

The invention concerns a deformable micro actuator with electrostatic motor for disc storage. Said microactuator located between the head and the suspension, consists of vertical electrodes (503, 504, 505) alternately maintained by an upper rigid horizontal plane (502), and a lower rigid horizontal plane (501), the horizontal planes being linked by a deformable peripheral elastomer membrane (500). The invention is useful for following narrow tracks for hard disc storage.

Description

MICRO-ACTIONNEUR CAPACITIF A STRUCTURE DEFORMABLE OPTIMISE POUR MEMOIRE A DISQUES ET PROCEDE DE FABRICATION CAPACITIVE MICRO ACTUATOR WITH OPTIMIZED DEFORMABLE STRUCTURE FOR DISC MEMORY AND MANUFACTURING METHOD
DESCRIPTIONDESCRIPTION
Domaine techniqueTechnical area
La présente invention a pour objet un micro-actioneur permettant à la tête d'écriture- lecture de suivre des pistes enregistrées de petite dimension, sur un disque dur , ainsi que son procédé de fabrication. 10 Elle trouve des applications dans le domaine des mémoires à disques durs, pour le stockage de masse d'informations.The subject of the present invention is a micro-actuator allowing the write-read head to follow recorded tracks of small size, on a hard disk, as well as its manufacturing process. 10 It finds applications in the field of hard disk memories, for mass storage of information.
Etat de l'art antérieureState of the prior art
Une mémoire à disque dur montrée schématiquement sur la figure 1 -* comprend essentiellement un ou plusieurs disques (100) revêtus d'une couche d'enregistrement support d'informations. La ou les têtes magnétiques d'écriture et de lecture (103) sont maintenues en position par une suspension (102). Cette suspension est montée sur un actionneur électromagnétique (101) , qui par rotation positionne la tête (103) sur laA hard disk memory shown schematically in Figure 1 - * essentially comprises one or more disks (100) coated with an information carrier recording layer. The magnetic writing and reading head (s) (103) are held in position by a suspension (102). This suspension is mounted on an electromagnetic actuator (101), which by rotation positions the head (103) on the
20 piste magnétique (104) qui sera lue, ou enregistrée. La piste (104) comporte des zones portant des informations particulières destinées à fournir à la tête des signaux qui après traitement seront envoyés à l'actionneur (101) afin de centrer en permanence la tête sur la piste (104). , D'une façon générale, les besoins de l'infoπnatique font que les capacités des mémoires à disques doublent en moyenne tous les 18 mois. Pour suivre cette forte croissance en densité d'enregistrement, il faut augmenter à la fois le nombre de bits d'informations le long de la piste ce que l'homme de l'art appelle la densité linéique, et à la fois augmenter le 3Q nombre de pistes , ce que l'homme de l'art appelle la densité radiale .20 magnetic strip (104) which will be read, or recorded. The track (104) comprises zones carrying particular information intended to supply the head with signals which after processing will be sent to the actuator (101) in order to permanently center the head on the track (104). In general, the needs of computer science mean that the capacities of disk memories double on average every 18 months. To follow this strong growth in recording density, it is necessary to increase both the number of bits of information along the track what the person skilled in the art calls the linear density, and at the same time increase the 3 Q number of tracks, what those skilled in the art call the radial density.
Il est admis que les actionneurs ne permettront pas d'atteindre une densité radiale supérieure à 1000 pistes par millimètre. Il devient donc indispensable d'adjoindre à l'actionneur selon l'art actuel, un autre actionneur, permettant un très faible déplacement de la tête, mais avec une grande précision, et une grande rapidité. C'est la raison pour laquelle l'industrie envisage un second étage d' actionneur, que l'on appelle micro- actioneur, comme montré sur la figure 2 . Plusieurs solutions ont été proposées pour réaliser ces micro- actioneurs. Celles qui paraissent les plus prometteuses, consistent à placer le micro-actioneur (200) entre la tête (103) et la suspension (102), comme le montre la figure 2. Le micro-actioneur (200) est réalisé par les technologies souvent appelées « MEM » qui en terme anglo-saxon sont o les initiales de Micro Electronic Machining, c'est à dire des technologies semblables à celles de circuit intégrés. La figure 3 montre le schéma d'un micro-actioneur selon l'art antérieur. On trouve la partie mobile (300) qui se déplace dans la direction des flèches (305). Cette partie mobile est maintenue par des poutres (301) qui forment un parallélogramme 5 deformable, relié à l'autre extrémité à une partie fixe (302). Ces poutres ont une épaisseur de 30 à 40 μm , et une largeur de 4 à 5 μm. Elles sont en silicium poly cristallin, ou parfois en nickel électrolysé. Attachés à la partie mobile (300), on trouve une série de peignes (303), entrelacés avec une autre série de peignes (304) reliés à la partie fixe (302) . La 0 séparation entre les peignes est de l'ordre de 3 μm. En appliquant une tension de l'ordre de 80 volts, entre les peignes, par attraction ou répulsion électrostatique, les peignes se rapprochent ou s'éloignent l'un de l'autre. On peut donc obtenir une excursion de la partie mobile du micro-actioneur de plus ou moins 1,5 μm. Les poutres (301) présentent 5 une fajble flexibilité dans la direction des flèches (305), et une plus grande rigidité perpendiculairement au plan de la figure 3. Toutes les formes et structures du micro-actioneur sont réalisées par les techniques MEM, proches de celles de la microélectronique. Il faut noter que l'on Q trouve des micro-actioneurs à déplacement rectiligne ou d'autres micro- actioneur à déplacements rotatifs. Un exemple de ces dispositifs est décrit dans la publication « Magnetic Recording Head Positioning at Very High Track Densities Using a Microactuator-Based Two-Stage Servo System » par L.S Fan, H.H Ottesen, T.C Reilley et R.W.Wood, IEEE Trans on Industrial Electronics, vol. 42, 3, pp. 222-223, June 1995. D'autres techniques utilisant la déformation de quartz piézoélectrique, ont été proposées.It is recognized that the actuators will not achieve a radial density greater than 1000 tracks per millimeter. It therefore becomes essential to add to the actuator according to current art, another actuator, allowing very little movement of the head, but with great precision and great speed. This is the reason why the industry is considering a second actuator stage, which is called a micro-actuator, as shown in FIG. 2. Several solutions have been proposed for producing these micro-actuators. Those which seem the most promising, consist in placing the micro-actuator (200) between the head (103) and the suspension (102), as shown in Figure 2. The micro-actuator (200) is produced by technologies often called “MEM” which in English terms are o the initials of Micro Electronic Machining, ie technologies similar to those of integrated circuits. FIG. 3 shows the diagram of a micro-actuator according to the prior art. There is the movable part (300) which moves in the direction of the arrows (305). This movable part is held by beams (301) which form a deformable parallelogram 5, connected at the other end to a fixed part (302). These beams have a thickness of 30 to 40 μm, and a width of 4 to 5 μm. They are made of poly crystalline silicon, or sometimes electrolysed nickel. Attached to the movable part (300), there is a series of combs (303), intertwined with another series of combs (304) connected to the fixed part (302). The 0 separation between the combs is of the order of 3 μm. By applying a voltage of the order of 80 volts, between the combs, by attraction or electrostatic repulsion, the combs move towards or away from each other. It is therefore possible to obtain an excursion of the mobile part of the micro-actuator of more or less 1.5 μm. The beams (301) have a slight flexibility in the direction of the arrows (305), and greater rigidity perpendicular to the plane of FIG. 3. All the shapes and structures of the micro-actuator are produced by MEM techniques, close to those of microelectronics. It should be noted that there are Q micro-actuators with rectilinear displacement or other micro-actuators with rotary displacements. An example of these devices is described in the publication “Magnetic Recording Head Positioning at Very High Track Densities Using a Microactuator-Based Two-Stage Servo System” by LS Fan, HH Ottesen, TC Reilley and RWWood, IEEE Trans on Industrial Electronics, vol . 42, 3, pp. 222-223, June 1995. Other techniques using the deformation of piezoelectric quartz have been proposed.
Bien que donnant satisfaction à certains égards, les micro- actioneurs, selon les structures décrites par la figure 3, présentent de nombreux défauts :Although satisfactory in certain respects, the micro-actuators, according to the structures described in FIG. 3, have many shortcomings:
La force d'attraction entre les peignes est directement liée à la capacité entre les peignes. Malgré des formes en créneaux qui permettent d'augmenter les surfaces en regard de ces peignes, la capacité ainsi formée est de 2 à 3 picofarads. L'énergie développées par ces micro- 0 actioneurs est donc très faible. Des peignes semblables à ceux des micro- actioneurs sont également utilisés pour réaliser des accéléromètres. Dans ce cas, les peignes sont protégés par un chapeau étanche, qui évite que des poussières, des particules, de rhumidité, puissent s'intercaler entre les peignes, pouvant perturber, ou même bloquer leur mouvement. Dans le cas des micro-actioneurs pour mémoire à disque, la partie mobile du micro-actioneur supporte la tête. Il est donc impossible selon cet art antérieur, d'étanchéifier les espaces entre les peignes pour éviter les agressions extérieures. On trouve ce problème à deux niveaux :The force of attraction between the combs is directly linked to the capacity between the combs. Despite the niche shapes which make it possible to increase the areas facing these combs, the capacity thus formed is from 2 to 3 picofarads. The energy developed by these micro-actuators is therefore very low. Combs similar to those of micro-actuators are also used to make accelerometers. In this case, the combs are protected by a watertight cap, which prevents dust, particles, rheumatism, can be interposed between the combs, which can disturb, or even block their movement. In the case of micro-actuators for disk storage, the mobile part of the micro-actuator supports the head. It is therefore impossible according to this prior art, to seal the spaces between the combs to avoid external aggressions. We find this problem on two levels:
— Toutes les opérations de montage du micro-actioneur sur la suspension, et de la tête sur le micro-actioneur, nécessitant des manipulations sont très risquées à cause de la fragilité des micro- actioneurs. Par exemple, la soudure des plots de sortie de la tête est très délicate, car c'est un procédé ultrasonique qui est souvent utilisé. Cette technique est incompatible avec la fragilité du micro-actioneur, qui serait 5 irrémédiablement détruit par l'énergie ultra-sonique. Avant d'être monté dans la mémoire à disque, l'ensemble suspension, micro-actioneur, tête d'écriture/lecture, subit de nombreux nettoyages, qui sont autant de cause de destruction du micro-actioneur, car si un liquide s'infiltre entre les n peignes, il est très difficile de l'en extraire. Ainsi, on peut dire que ces micro-actioneurs, sont difficilement compatibles avec les procédés d'assemblage utilisés actuellement dans l'industrie.- All the mounting operations of the micro-actuator on the suspension, and of the head on the micro-actuator, requiring manipulations are very risky because of the fragility of the micro-actuators. For example, the welding of the head output pads is very delicate, because it is an ultrasonic process which is often used. This technique is incompatible with the fragility of the micro-actuator, which would be irreparably destroyed by the ultrasonic energy. Before being mounted in the disc memory, the suspension, micro-actuator, write / read head assembly undergoes numerous cleanings, which are as many causes of destruction of the micro-actuator, because if a liquid infiltrate between the n combs, it is very difficult to extract it. Thus, it can be said that these micro-actuators are hardly compatible with the assembly processes currently used in industry.
— Le risque est tout aussi grand, lorsque le micro-actioneur supportant la tête est en fonctionnement à l'intérieur de la mémoire à disque. La tête vole à quelques dizaines de nanomètres au dessus du disque. A l' arrière de la tête on trouve au cours du temps des accumulations de fines particules , issues des atterrissages et décollages de la tête. Ces particules ne gênent pas le vol de la tête. Par contre, les mêmes particules, peuvent pénétrer entre les peignes du micro-actioneur qui sont situés juste sous la tête, et bloquer son fonctionnement. Par ailleurs, la mémoire à disque est parfois soumise à des chocs accidentels. Selon les normalisations internationales, une mémoire a disque doit pouvoir accepter des chocs supérieurs à 500 g . L'énergie du choc se transmet du disque vers la tête. Cette dernière décolle du disque, puis est rabattue avec violence par la suspension sur le disque. Le micro-actioneur risquerait d'être gravement endommagé.- The risk is just as great, when the micro-actuator supporting the head is in operation inside the disk memory. The head flies a few tens of nanometers above the disc. At the back of the head we find over time accumulations of fine particles, coming from the landings and takeoffs of the head. These particles do not interfere with the flight of the head. On the other hand, the same particles can penetrate between the combs of the micro-actuator which are located just under the head, and block its operation. In addition, the disk memory is sometimes subjected to accidental shocks. According to international standards, a disk memory must be able to accept shocks greater than 500 g. The energy of the shock is transmitted from the disc to the head. The latter takes off from the disc, then is violently lowered by the suspension on the disc. The micro-actuator could be seriously damaged.
Afin d'éviter ces inconvénients, une nouvelle structure, représentée sur les figures 4A, 4B, et 4C, a été proposée par la demande de brevet d'invention N° 9906430 du 18 mai 1999. Il s'agit d'une structure deformable utilisant un élastomère du type latex (200) ayant un faible module d'Young, qui sous l'influence de couches conductrices (403) déposées dans le plan du micro-actionneur, décalées les unes des autres, formant un moteur électrostatique, qui génère des forces de cisaillement, déforment l' élastomère, produisant un déplacement du plan supérieur du micro-actionneur (401) , par rapport au plan inférieur (402), comme le montrent les figures 4B et 4C, selon les polarisations électriques des électrodes (403) .In order to avoid these drawbacks, a new structure, represented in FIGS. 4A, 4B, and 4C, was proposed by the patent application No. 9906430 of May 18, 1999. It is a deformable structure using a latex type elastomer (200) having a low Young's modulus, which under the influence of conductive layers (403) deposited in the plane of the micro-actuator, offset from each other, forming an electrostatic motor, which generates shear forces, deform the elastomer, producing a displacement of the upper plane of the micro-actuator (401), relative to the lower plane (402), as shown in FIGS. 4B and 4C, according to the electrical polarizations of the electrodes (403 ).
Bien que donnant satisfaction à certains égards, les micro- actioneurs utilisant la déformation d'un élastomère, décrits précédemment, présentent une rigidité importante face aux forces de déformation produites par le moteurs électrostatique.Although satisfactory in certain respects, the micro-actuators using the deformation of an elastomer, described above, exhibit significant rigidity in the face of the deformation forces produced by the electrostatic motors.
La présente invention ajustement pour but de remédier à ces inconvénients, en proposant une structure de moteur électrostatique beaucoup plus efficace d'une part, et une structure deformable à base d'élastomère offrant une plus faible rigidité dans le sens des déplacements, d'autre part, ainsi que le procédé de fabrication. Exposé de l'inventionThe present invention adjustment aims to remedy these drawbacks, by providing a much more efficient electrostatic motor structure on the one hand, and a deformable structure based on elastomer offering lower rigidity in the direction of movement, on the other hand part, as well as the manufacturing process. Statement of the invention
A cette fin, l'invention propose un micro-actioneur constitué d'une membrane périphérique deformable en matériau du type élastomère, séparant deux plans horizontaux qui maintiennent des électrodes verticales formant un condensateur. Les électrodes verticales sont séparées par une distance légèrement supérieure au déplacement des deux plans horizontaux, ce qui fait que le volume interne à la membrane périphérique est entièrement occupé par le moteur électrostatique, lui permettant de générer des forces très importantes, en regard de celles nécessaires à la déformation de la membrane périphérique. Les électrodes verticales sont alternativement attachées au plan horizontal supérieur, et au plan horizontal inférieur. Leur polarisation électrique est telle que les électrodes verticales supérieures sont soumises à des forces d'attraction par rapport aux électrodes verticales inférieures. Le micro-actioneur selon l'invention, présente une grande flexibilité dans la direction de déplacement, et une forte rigidité perpendiculairement au plan du micro-actioneur, ce qui lui permet d'encaisser des chocs, et même de les amortir. Selon l'invention, le micro-actioneur est très robuste, et il est insensible aux particules, ou aux liquides. Les électrodes sont dans un volume totalement isolé de l'extérieur " par la membrane périphérique. Il fonctionne avec des tensions inférieures à 100 Volts. Il ne présente pas de fatigue ni d'hystérésis à un niveau gênant pour son fonctionnement. Il est parfaitement compatible avec les procédés actuellement utilisés dans l'industrie pour l'assemblage des têtes sur leur suspension. Il ne présente aucun risque à l'intérieur de la mémoire à disque face à l'accumulation de particules. Vu de l'extérieur, il se présente sous la forme d'un volume homogène, qui se déforme en fonction des forces générées par le moteur électrostatique.To this end, the invention provides a micro-actuator consisting of a deformable peripheral membrane made of an elastomer type material, separating two horizontal planes which hold vertical electrodes forming a capacitor. The vertical electrodes are separated by a distance slightly greater than the displacement of the two horizontal planes, which means that the internal volume of the peripheral membrane is entirely occupied by the electrostatic motor, allowing it to generate very large forces, compared to those necessary deformation of the peripheral membrane. The vertical electrodes are alternately attached to the upper horizontal plane, and to the lower horizontal plane. Their electrical polarization is such that the upper vertical electrodes are subjected to attractive forces relative to the lower vertical electrodes. The micro-actuator according to the invention has great flexibility in the direction of movement, and high rigidity perpendicular to the plane of the micro-actuator, which allows it to absorb shocks, and even to absorb them. According to the invention, the micro-actuator is very robust, and it is insensitive to particles, or to liquids. The electrodes are in a volume totally isolated from the outside "by the peripheral membrane. It operates with voltages less than 100 Volts. It does not present any fatigue or hysteresis at a level which interferes with its operation. It is perfectly compatible with the processes currently used in the industry for assembling heads on their suspension. It presents no risk inside the disk memory in the face of the accumulation of particles. in the form of a homogeneous volume, which deforms according to the forces generated by the electrostatic motor.
De façon plus précise, la présente invention a pour objet, un micro- actioneur pour mémoire à disques, et son précédé de fabrication, constitué d'un ensemble d'électrodes planes verticales maintenues alternativement par un plan horizontal supérieur et par un plan horizontal inférieur, les plans horizontaux supérieur et inférieur, étant tenus par une membrane périphérique deformable du type élastomère, comme du caoutchouc du latex, ou du silicone. La polarisation électrique des électrodes verticales, génère sur chacune d'elle des forces d'attraction par rapport aux électrodes voisines. La membrane deformable qui supporte les plans horizontaux supérieurs et inférieurs, assure l'étanchéité du moteur électrostatique, par rapport à l'environnement extérieur au micro-actioneur. Le plan horizontal inférieur du micro-actioneur est collé sur la suspension, le plan horizontal supérieur du micro-actioneur supporte la tête. La déformation de la membrane périphérique est très petite par rapport à sa hauteur, ce qui engendre une hystérésis et une fatigue négligeables. Le micro-actioneur, selon l'invention, présente une capacité sensiblement supérieure à celle des micro-actioneurs selon l'art antérieur. L'intensité des forces engendrées par le moteur électrostatique, dont les électrodes se déplacent perpendiculairement à leur plan, est sensiblement plus importante que celle des moteurs électrostatiques de l'art antérieur. Selon un autre mode de l'invention, la membrane périphérique entre les plans horizontaux supérieur et inférieur, a une forme optimisée, afin qu'elle offre une faible résistance à la déformation, dans la direction du déplacement. Selon un autre mode préféré de l'invention, le micro-actioneur a un pivot central, permettant de faire pivoter l'un par rapport à l'autre les plans horizontaux supérieur et inférieur. Le micro-actioneur selon l'une quelconque des structures décrites précédemment, présente une grande rigidité verticale. En cas de choc, le matériau deformable de par son élasticité, absorbera le choc, évitant par la même une détérioration de la tête, du micro-actioneur lui même, ou de la surface du disque. Selon l'invention, le déplacement de la surface supérieure du micro- actioneur par rapport à sa surface inférieure, peut-être rectiligne, ou rotatif. Ce déplacement peut être mesuré par la variation de capacité entre des électrodes voisine. Il est donc possible d'asservir les déplacements du micro-actioneur, et par là même de s'affranchir de possibles non linéarités dans la déformation de la membrane périphérique.More specifically, the present invention relates to a micro-actuator for disk storage, and its manufacturing method, consisting of a set of vertical planar electrodes held alternately by an upper horizontal plane and by a lower horizontal plane. , the upper and lower horizontal planes, being held by a deformable peripheral membrane of the elastomer type, such as latex rubber, or silicone. The electrical polarization of the vertical electrodes, generates on each of them attractive forces relative to neighboring electrodes. The deformable membrane which supports the upper and lower horizontal planes, seals the electrostatic motor, in relation to the environment external to the micro-actuator. The lower horizontal plane of the micro-actuator is glued to the suspension, the upper horizontal plane of the micro-actuator supports the head. The deformation of the peripheral membrane is very small compared to its height, which causes negligible hysteresis and fatigue. The micro-actuator according to the invention has a capacity substantially greater than that of the micro-actuators according to the prior art. The intensity of the forces generated by the electrostatic motor, whose electrodes move perpendicular to their plane, is significantly greater than that of the electrostatic motors of the prior art. According to another embodiment of the invention, the peripheral membrane between the upper and lower horizontal planes has an optimized shape, so that it offers low resistance to deformation, in the direction of movement. According to another preferred embodiment of the invention, the micro-actuator has a central pivot, making it possible to pivot one relative to the other the upper and lower horizontal planes. The micro-actuator according to any one of the structures described above has great vertical rigidity. In the event of impact, the deformable material due to its elasticity, will absorb the impact, thereby preventing deterioration of the head, of the micro-actuator itself, or of the surface of the disc. According to the invention, the displacement of the upper surface of the micro-actuator relative to its lower surface, perhaps rectilinear, or rotary. This displacement can be measured by the variation in capacitance between neighboring electrodes. It is therefore possible to control the displacements of the micro-actuator, and thereby to get rid of possible non-linearities in the deformation of the peripheral membrane.
D'autres caractéristiques et avantages de l'invention, ressortiront mieux de la description qui va suivre, donnée à titre illustratif mais non limitatif, en référence aux dessins annexés. Brève description des dessins.Other characteristics and advantages of the invention will emerge more clearly from the description which follows, given by way of illustration but not limitation, with reference to the appended drawings. Brief description of the drawings.
<* les figures 1, déjà décrite, montre le schéma d'une mémoire à disques •* la figure 2 , déjà décrite, montre la position du micro-actioneur, entre la tête et la suspension.<* Figures 1, already described, shows the diagram of a disk memory • * Figure 2, already described, shows the position of the micro-actuator, between the head and the suspension.
•> la figure 3 déjà décrite, montre la structure d'un micro-actioneur selon un art antérieur, • les figures 4 A, 4B, 4C, déjà décrites, montrent une structure d'un micro-actioneur selon un autre art antérieur utilisant la déformation d'un matériau du type élastomère, ainsi que les déplacements des plans (401) et (402) selon la polarité des électrodes. •* les figure 5 montre la coupe d'un micro-actionneur selon l'invention. la figure 6 montre le mouvement du plan horizontal supérieur par rapport au plan horizontal inférieur. la figure 7 montre un micro-actionneur à déplacement circulaire, la figure 8 montre le procédé de réalisation du premier groupe d'électrodes verticales, attachées au plan inférieur. la figure 9 montre le procédé de réalisation du second groupe d'électrodes verticales attachées au plan supérieur. * la figure 10 montre le procédé de réalisation de la membrane périphérique ainsi que celui du plan supérieur.•> Figure 3 already described, shows the structure of a micro-actuator according to a prior art, • Figures 4 A, 4B, 4C, already described, show a structure of a micro-actuator according to another prior art using the deformation of a material of the elastomer type, as well as the displacements of the planes (401) and (402) according to the polarity of the electrodes. • * Figure 5 shows the section of a micro-actuator according to the invention. Figure 6 shows the movement of the upper horizontal plane relative to the lower horizontal plane. FIG. 7 shows a micro-actuator with circular displacement, FIG. 8 shows the process for producing the first group of vertical electrodes, attached to the lower plane. FIG. 9 shows the process for producing the second group of vertical electrodes attached to the upper plane. * Figure 10 shows the process for producing the peripheral membrane as well as that of the upper plane.
Exposé détaillé d'un mode de réalisation :Detailed description of an embodiment:
La figure 5 montre un premier mode de réalisation du micro- actioneur selon l'invention. Le micro-actioneur (200) selon un premier mode de l'invention, se présente sous la forme d'un parallélépipède plat. Sa largeur et sa longueur sont sensiblement égales à celles de la tête (103) de la figure 2, qui sera collée sur sa surface supérieure (502), tandis que sa surface inférieure (501) sera collée sur la suspension (102) de la figure 2. L'épaisseur du micro-actioneur (200) est de l'ordre de 30μm à lOOμm, sa longueur de 1,25 mm, et sa largeur de 1mm, lorsque la tête (103) est au format international dit « pico » . Le micro-actioneur (200) apparaît de OFIG. 5 shows a first embodiment of the micro-actuator according to the invention. The micro-actuator (200) according to a first embodiment of the invention, is in the form of a flat parallelepiped. Its width and length are substantially equal to those of the head (103) of Figure 2, which will be glued to its upper surface (502), while its lower surface (501) will be glued to the suspension (102) of the figure 2. The thickness of the micro-actuator (200) is of the order of 30 μm to 100 μm, its length 1.25 mm, and its width 1 mm, when the head (103) is in the international format known as “pico " The micro-actuator (200) appears from O
L'extérieur, comme un parallélépipède plat, constitué de deux surfaces rigides (502) et (501) reliées entre elles par une membrane périphérique deformable (500), constituée d'un élastomère, comme du caoutchouc, du latex, ou du silicone, donné à titre d'exemple non limitatif. L'élasticité d'un matériau se définit par son module d'Young. Le nickel par exemple a un module d'Young de 200 Giga Pascal (200Gpa). Le silicium supérieur à lOOGpa. Les élastomères déformables (500) selon l'invention, présentent un module d'Young compris entre 0,1 Méga Pascal (0,1 Mpa), et 100 Mpa. Le latex par exemple a un module d'Young compris entre 4Mpa et 40Mpa. A l'intérieur du micro-actionneur, on trouve un ensemble d'électrodes verticales supportées alternativement par les plans (502) et (501). Ainsi, les électrodes (503) et (505) sont tenues par le plan supérieur (502), alors que l'électrode (504) est tenue par le plan inférieur (501). Ces électrodes une fois alimentées par une tension électrique, forment un moteur électrostatique, qui génère des forces horizontales entre chaque électrode, qui se transmettent aux surfaces rigides supérieure (502) et inférieure (501). Ces surfaces sous l'effet des forces produites par les électrodes vont se déplacer en déformant légèrement la membrane périphérique (500). La figure 6 montre un exemple de déplacement. Supposons que l'électrode (503) ait la même polarité que l'électrode (504), et que l'électrode (504) soit polarisée positivement par rapport à l'électrode 505), l'électrode (505) sera attirée par l'électrode (504), alors que l'électrode (505) ne subira aucune force par rapport à l'électrode (504). On voit donc, selon l'invention, que selon les polarité des électrodes supérieures par rapport aux électrodes inférieures, des forces d'attraction entre les électrodes supérieures et inférieures, permettent un déplacement du plans horizontal supérieur par rapport au plan horizontal inférieur. A titre d'exemple, si l'on considère un micro-actioneur ayant les dimensions définies précédemment, les électrodes forment une capacité de l'ordre de 58pf, et génèrent une force de l'ordre de 0,24 Newtons, pour une tension appliquée de 100 volts. Si les déplacements maximum recherchés entre le plan supérieur (502) et le plan inférieur (501) sont de plus ou moins 1 μm, alors la séparation entre chaque électrode sera légèrement supérieure à 1 μm, soit par exemple l,5μm. Afin d'éviter tout court circuit entre électrode si à cause d'un problème quelconque, le déplacement du plan supérieur par rapport au plan inférieur était plus grand quel,5μm qui ferait que les électrodes puissent se toucher, l'ensemble des électrodes attachées au plan horizontal inférieur par exemple, selon l'invention sont isolées par une couche mince diélectrique. Selon l'invention, le micro-actionneur a une forme rectangulaire, avec un mouvement rectiligne du plan supérieur par rapport au plan inférieur. Afin de réduire la rigidité de la partie de la membrane périphérique parallèle au déplacement, selon un mode optimisé de l'invention, la forme de ces parties de la membrane, peuvent avantageusement être circulaires, ou coudées . Selon un autre mode de réalisation, le micro-actionneur est rotatif. Dans ce cas, les plans supérieur (502) et inférieur (501) ont une forme circulaire. Les électrodes verticales sont positionnées selon des rayons, et la membrane périphérique extérieure est circulaire, comme le montre la figure 7 vue en plan. On retrouve la membrane périphérique (500), les électrodes verticales (503) , (504) , (505), installées sous forme de rayons, attachées alternativement aux surfaces supérieures et inférieures du micro- actionneur. Au centre, on trouve un pilier (700) qui présente une rigidité importante dans le plan, mais une faible rigidité en rotation.The outside, like a flat parallelepiped, made up of two rigid surfaces (502) and (501) linked together by a deformable peripheral membrane (500), made up of an elastomer, such as rubber, latex, or silicone, given by way of nonlimiting example. The elasticity of a material is defined by its Young's modulus. Nickel for example has a Young's modulus of 200 Giga Pascal (200Gpa). The silicon superior to OOGpa. The deformable elastomers (500) according to the invention have a Young's modulus of between 0.1 Mega Pascal (0.1 Mpa) and 100 Mpa. Latex, for example, has a Young's modulus between 4Mpa and 40Mpa. Inside the micro-actuator, there is a set of vertical electrodes supported alternately by the planes (502) and (501). Thus, the electrodes (503) and (505) are held by the upper plane (502), while the electrode (504) is held by the lower plane (501). These electrodes, once supplied with an electric voltage, form an electrostatic motor, which generates horizontal forces between each electrode, which are transmitted to the upper (502) and lower (501) rigid surfaces. These surfaces under the effect of the forces produced by the electrodes will move by slightly deforming the peripheral membrane (500). Figure 6 shows an example of displacement. Suppose that the electrode (503) has the same polarity as the electrode (504), and that the electrode (504) is positively polarized with respect to the electrode 505), the electrode (505) will be attracted by l electrode (504), while the electrode (505) will not be subjected to any force relative to the electrode (504). It can therefore be seen, according to the invention, that according to the polarity of the upper electrodes relative to the lower electrodes, attractive forces between the upper and lower electrodes allow a displacement of the upper horizontal plane with respect to the lower horizontal plane. For example, if we consider a micro-actuator having the dimensions defined above, the electrodes form a capacity of the order of 58pf, and generate a force of the order of 0.24 Newtons, for a voltage applied from 100 volts. If the maximum displacements sought between the upper plane (502) and the lower plane (501) are plus or minus 1 μm, then the separation between each electrode will be slightly greater than 1 μm, ie for example 1.5 μm. In order to avoid any short circuit between electrodes if due to a any problem, the displacement of the upper plane relative to the lower plane was greater than, 5 μm which would cause the electrodes to be able to touch, all of the electrodes attached to the lower horizontal plane for example, according to the invention are isolated by a layer thin dielectric. According to the invention, the micro-actuator has a rectangular shape, with a rectilinear movement of the upper plane relative to the lower plane. In order to reduce the rigidity of the part of the peripheral membrane parallel to the displacement, according to an optimized mode of the invention, the shape of these parts of the membrane can advantageously be circular, or bent. According to another embodiment, the micro-actuator is rotary. In this case, the upper (502) and lower (501) planes have a circular shape. The vertical electrodes are positioned along radii, and the outer peripheral membrane is circular, as shown in Figure 7 in plan view. We find the peripheral membrane (500), the vertical electrodes (503), (504), (505), installed in the form of rays, attached alternately to the upper and lower surfaces of the micro-actuator. In the center, there is a pillar (700) which has a high rigidity in the plane, but a low rigidity in rotation.
Le déplacement relatif des deux surfaces supérieure et inférieure, est de l'ordre de plus ou moins un à deux microns. Si l'épaisseur du micro-actioneur est de 100 μm , la déformation de la membrane périphérique ne sera que de quelques pour-cent. Les matériaux déformables selon l'invention peuvent accepter des déformations élastiques de l'ordre de 700 pour-cent. Les déformations du micro- actioneur selon l'invention, sont tellement petites par rapport à ce que le matériau pourrait encaisser, qu'elles ne s'accompagnent ni d'hystérésis, ni de fatigue. En mesurant la capacité entre les électrodes (503) et (504) par exemple, qui traduit directement la séparation entre ces électrodes, c'est à dire qui donne une mesure précise des déplacements, il est possible de réaliser une boucle d'asservissement électronique, qui de ce fait annule toute non linéarité dans les déplacements.The relative displacement of the two upper and lower surfaces is of the order of plus or minus one to two microns. If the thickness of the micro-actuator is 100 μm, the deformation of the peripheral membrane will only be a few percent. The deformable materials according to the invention can accept elastic deformations of the order of 700 percent. The deformations of the micro-actuator according to the invention are so small compared to what the material could collect, that they are not accompanied by either hysteresis or fatigue. By measuring the capacity between the electrodes (503) and (504) for example, which directly translates the separation between these electrodes, that is to say which gives an accurate measurement of the displacements, it is possible to produce an electronic control loop , which thus cancels any nonlinearity in displacements.
Le micro-actioneur (200) selon l'invention, apparaît comme un ensemble homogène, sans micro-cavités. Il est inerte chimiquement, notamment aux agents liquides de nettoyage. Il est très robuste mécaniquement, surtout dans les directions perpendiculaires au plan des surfaces (501) et (502). Comme la membrane périphérique reliant les deux plans rigides du micro-actionneur, est constitué de matériau deformable, et comme le micro-actionneur est situé entre la suspension et la tête, il constitue un parfait amortisseur de chocs.The micro-actuator (200) according to the invention appears as a homogeneous whole, without micro-cavities. It is chemically inert, especially to liquid cleaning agents. It is very robust mechanically, especially in directions perpendicular to the plane of the surfaces (501) and (502). As the peripheral membrane connecting the two rigid planes of the micro-actuator, is made of deformable material, and as the micro-actuator is located between the suspension and the head, it constitutes a perfect shock absorber.
Procédé de fabrication :Manufacturing process :
Sur un substrat (800) qui peut avantageusement être une tranche de silicium, comme utilisé dans le domaine de la microélectronique, on dépose une première couche (801) dite « sacrificielle », c'est à dire que l'on éliminera par la suite. Cette couche peut-être de la résine, ou un polymère que l'on peut dissoudre dans des solvants spécifiques, ou une couche métallique ou diélectrique, connus de l'homme de l'art. La couche sacrificielle peut avoir une épaisseur de quelques microns. Sur cette couche sacrificielle, on dépose une couche diélectrique (501) qui constituera la surface inférieure du micro-actionneur. Cette couche peut être du Si02 par exemple déposé selon des procédés à basse température, comme le CVD soit en terme anglo-saxon « Chemical Vapor Déposition », procédé connu de l'homme de l'art. La couche de Si02 peut avoir une épaisseur de l'ordre de quelques microns. Sur cette couche de Si02, on dépose une couche conductrice qui après photolithographie et gravure, techniques connues des procédés de la microélectronique, constituera des interconnexions (802) reliés à la source de tension, sur lesquels on va réaliser le premier ensemble d'électrodes . On dépose ensuite une couche de résine photosensible (803) d'épaisseur de quelques microns à une centaine de microns. On réalise ensuite une lithographie, suivie d'une révélation qui va réaliser des tranchées (804) dans la résine, ces tranchées débouchant vers le bas sur les conducteurs (802) . On comblera ensuite ces tranchées par croissance électrolytique d'un conducteur, comme du cuivre, ou du nickel par exemple. D'autres méthodes de comblement connues de l'homme de l'art, comme le CVD par exemple peuvent également être utilisées. On élimine ensuite la résine, et on dépose sur toutes les surfaces des électrodes, une couche diélectrique fine de l'ordre de 1000 A°, comme du Si02 par exemple, en utilisant un dépôt CVD par exemple, afin que le dépôt soit le plus homogène possible . Cette couche isolera les électrodes.On a substrate (800) which can advantageously be a silicon wafer, as used in the field of microelectronics, a first layer (801) called "sacrificial" is deposited, that is to say that will be eliminated thereafter. . This layer may be resin, or a polymer which can be dissolved in specific solvents, or a metallic or dielectric layer, known to those skilled in the art. The sacrificial layer may have a thickness of a few microns. On this sacrificial layer, a dielectric layer (501) is deposited which will constitute the lower surface of the micro-actuator. This layer can be SiO 2, for example deposited according to low temperature processes, such as CVD or in English term "Chemical Vapor Deposition", process known to those skilled in the art. The Si02 layer can have a thickness of the order of a few microns. On this layer of Si02, a conductive layer is deposited which, after photolithography and etching, techniques known from microelectronic processes, will constitute interconnections (802) connected to the voltage source, on which the first set of electrodes will be produced. A layer of photosensitive resin (803) is then deposited from a few microns to a hundred microns thick. A lithography is then carried out, followed by a revelation which will produce trenches (804) in the resin, these trenches opening down onto the conductors (802). These trenches will then be filled by electrolytic growth of a conductor, such as copper, or nickel for example. Other filling methods known to those skilled in the art, such as CVD for example, can also be used. The resin is then removed, and a thin dielectric layer of the order of 1000 A ° is deposited on all the surfaces of the electrodes, such as SiO 2 for example. using a CVD deposit for example, so that the deposit is as homogeneous as possible. This layer will isolate the electrodes.
Sur cet ensemble, on dépose une couche de résine, ou de matériau organique disolvable par un solvant connu de l'homme de l'art. Cette couche (900) de la figure 9, a une épaisseur supérieure à la hauteur du premier ensemble d'électrodes (804) . Sur cette couche (900), on dépose une couche de Si02 (901) qui servira de masque de gravure de la couche (900). Après lithographie, et gravure de la couche de Si02 (901), on grave la couche (900) sous forme de tranchées (902) , dont le fond ne touchera pas la couche (501) . Le fond pourra se situer à environ 5 μm au dessus de la couche (501). On dépose ensuite une couche mince conductrice (903) qui tapissera l'intérieur des tranchées (902). En utilisant cette couche conductrice comme électrode, on fera pousser par électrolyse un matériaux conducteur comme du nickel ou du cuivre à l'intérieur des tranchées (902) constituant ainsi un second ensemble d'électrodes qui seront attachées au plan supérieur. On peut également utiliser un dépôt CVD pour combler les tranchées (902 . Sur la surface (903), on réalise ensuite une lithographie, suivie d'une gravure pour faire les connexionsOn this assembly, a layer of resin, or of organic material dissolvable with a solvent known to a person skilled in the art, is deposited. This layer (900) of FIG. 9 has a thickness greater than the height of the first set of electrodes (804). On this layer (900), a layer of Si02 (901) is deposited which will serve as an etching mask for the layer (900). After lithography, and etching of the Si02 layer (901), the layer (900) is etched in the form of trenches (902), the bottom of which will not touch the layer (501). The bottom may be around 5 μm above the layer (501). A thin conductive layer (903) is then deposited which will line the inside of the trenches (902). By using this conductive layer as an electrode, a conductive material such as nickel or copper will be grown by electrolysis inside the trenches (902) thus constituting a second set of electrodes which will be attached to the upper plane. One can also use a CVD deposit to fill the trenches (902. On the surface (903), one then realizes a lithography, followed by an engraving to make the connections
(1000) des électrodes du plan supérieur, comme le montre la figure 10. Les connections (1000) relient donc les électrodes supérieures à la source de tension. On réalise ensuite une lithographie suivie d'une gravure de la couche de Si02 (901), afin de réaliser par gravure sélective, une tranchée(1000) of the electrodes of the upper plane, as shown in Figure 10. The connections (1000) therefore connect the upper electrodes to the voltage source. A lithography is then carried out followed by an etching of the layer of Si02 (901), in order to produce by selective etching, a trench
(1001) dans la couche (900) . Cette tranchée peut avoir une largeur de 10 à lOOμm par exemple. Elle a la forme de la membrane périphérique. Cette trancjhée est ensuite comblée par l' élastomère. Il se présentent sous la forme soit liquide, soit pâteuses , et se polymérise par ajout d'un liquide de polymérisation, associé à une température de l'ordre de 50°C. L' élastomère peut-être déposé soit à la raclette, soit par centrifugation. On dépose sur l'ensemble une couche de Si02 épaisse, de plusieurs microns (1003) . On réalise ensuite une lithographie sur la couche de Si02 (1003), afin de réaliser de nombreuses ouvertures, qui laissent la couche de Si02 sous la forme d'une grille (1002) ouverte, jusqu'à la surface de la couche (900). On grave sélectivement par gravure ionique réactive, la couche (900), au travers des trous de la grille de Si02, puis on élimine totalement la couche (900) par dissolution sélective à l'aide d'un solvant approprié, connu de l'homme de l'art. On obtient donc la structure complète du micro-actionneur selon l'invention. Les électrodes supérieures sont tenues par la grille de Si02 rigide , réalisée dans la couche épaisse (1003), qui est déposée sur la membrane périphérique (1001) . On dépose par collage, sur la couche épaisse de Si02 en forme de grille (1003) une couche qui peut-être un polymère , d'une dizaine de microns d'épaisseur, qui assurera l'étanchéité totale du micro-actionneur. On élimine enfin la première couche sacrificielle (801) afin de libérer chaque micro-actionneur du substrat (800) qui les a tenus pendant toute les étapes de fabrication. (1001) in layer (900). This trench can have a width of 10 to 100 μm for example. It has the shape of the peripheral membrane. This trancjhée is then filled by the elastomer. They are in either liquid or pasty form, and polymerize by adding a polymerization liquid, associated with a temperature of the order of 50 ° C. The elastomer can be deposited either with a squeegee or by centrifugation. A thick layer of SiO 2, several microns (1003), is deposited on the whole. A lithography is then carried out on the layer of Si02 (1003), in order to produce numerous openings, which leave the layer of Si02 in the form of a grid (1002) open, up to the surface of the layer (900) . The layer (900) is selectively etched by reactive ion etching, through the holes in the SiO 2 grid, then the layer (900) is completely eliminated by selective dissolution using a solvent. suitable, known to those skilled in the art. The complete structure of the micro-actuator according to the invention is therefore obtained. The upper electrodes are held by the rigid Si02 grid, made in the thick layer (1003), which is deposited on the peripheral membrane (1001). Is deposited by bonding, on the thick layer of Si02 in the form of grid (1003) a layer which may be a polymer, of ten microns thick, which will ensure the total sealing of the micro-actuator. Finally, the first sacrificial layer (801) is eliminated in order to free each micro-actuator from the substrate (800) which held them during all the manufacturing stages.

Claims

REVENDICATIONS
1. Micro-actioneur pour mémoire à disque, disposé entre la tête (103) et la suspension (102) animé par un moteur électrostatique, caractérisé en ce que le moteur électrostatique est constitué d'électrodes planes verticales (503), (504),(505) tenues alternativement par deux plans rigides horizontaux (502) et (501), les deux plans horizontaux étant reliés par une membrane périphérique deformable (500).1. Micro-actuator for disk memory, disposed between the head (103) and the suspension (102) driven by an electrostatic motor, characterized in that the electrostatic motor consists of vertical plane electrodes (503), (504) , (505) held alternately by two rigid horizontal planes (502) and (501), the two horizontal planes being connected by a deformable peripheral membrane (500).
2. Micro-actioneur pour mémoire à disque, selon la revendication 1 caractérisé en ce que la membrane périphérique (500) est un élastomère du type caoutchouc, latex, silicone, ayant un module d'Young compris entre 0,1 et lOOMpa.2. Micro-actuator for disk memory, according to claim 1 characterized in that the peripheral membrane (500) is an elastomer of the rubber, latex, silicone type, having a Young's modulus between 0.1 and lOOMpa.
3. Micro-actioneur pour mémoire à disque, selon la revendication 2 caractérisé en ce que les électrodes verticales soient isolées les unes des autres par une couche diélectrique.3. Micro-actuator for disk storage, according to claim 2 characterized in that the vertical electrodes are isolated from each other by a dielectric layer.
4. Micro-actioneur pour mémoire à disques, selon l'une quelconque des revendications 1 à 3 , caractérisé en ce que les électrodes verticales (503), (504), (505), soient dans un milieu étanche protégé par la membrane périphérique deformable (500) et les deux plans horizontaux (501) et (502), par rapport à l' environnement extérieur au micro-actionneur.4. Micro-actuator for disk storage, according to any one of claims 1 to 3, characterized in that the vertical electrodes (503), (504), (505), are in a sealed environment protected by the peripheral membrane deformable (500) and the two horizontal planes (501) and (502), relative to the environment external to the micro-actuator.
- 5. Micro-actioneur pour mémoire à disques, selon l'une quelconque des revendications 1 à 4, caractérisé en ce que le micro-actionneur a un déplacement linéaire, ou un déplacement rotatif.- 5. Micro-actuator for disk storage, according to any one of claims 1 to 4, characterized in that the micro-actuator has a linear movement, or a rotary movement.
6. Micro-actioneur pour mémoire à disque, selon l'une quelconque des revendications 1 à 5 caractérisé en ce qu'il comporte des moyens de mesure de la capacité entre deux électrodes voisines, représentative du déplacement du micro-actionneur. 6. Micro-actuator for disk memory, according to any one of claims 1 to 5 characterized in that it comprises means for measuring the capacity between two neighboring electrodes, representative of the displacement of the micro-actuator.
7. Micro-actioneur pour mémoire à disque, selon l'une quelconque des revendications 1 à 6, caractérisé en ce que les plans horizontaux (501) et (502) sont reliés par un matériau élastique qui absorbe les chocs mécaniques, entre la suspension (102) , et la tête (103).7. Micro-actuator for disk memory, according to any one of claims 1 to 6, characterized in that the horizontal planes (501) and (502) are connected by an elastic material which absorbs mechanical shock, between the suspension (102), and the head (103).
8. Procédé de fabrication du micro-actionneur pour mémoire à disque, selon la revendication 1 dans lequel on réalise les étapes suivantes :8. A method of manufacturing the micro-actuator for disk storage, according to claim 1, in which the following steps are carried out:
— Sur un substrat (800), on dépose une couche sacrificielle (801), puis une couche rigide (501) isolante. — On réalise un premier niveau d'interconnexions (802) du premier ensemble d'électrodes maintenues sur le plan horizontal inférieur.- On a substrate (800), a sacrificial layer (801) is deposited, then a rigid insulating layer (501). - A first level of interconnections (802) of the first set of electrodes maintained on the lower horizontal plane is produced.
— On dépose une couche épaisse de résine (803) dans laquelle on réalise des tranchées (804) que l'on comble par un matériau conducteur.- A thick layer of resin (803) is deposited in which trenches (804) are produced which are filled with a conductive material.
— On élimine la résine (803) — On dépose une couche mince diélectrique d'isolation qui recouvre les électrodes.- The resin is removed (803) - A thin dielectric layer of insulation is deposited which covers the electrodes.
— On dépose une couche sacrificielle organique (900) d'épaisseur supérieure à la hauteur du premier ensemble d'électrodes.- An organic sacrificial layer (900) thicker than the height of the first set of electrodes is deposited.
— On dépose une couche de Si02 (901) sur la couche sacrificielle (900)- We deposit a layer of Si02 (901) on the sacrificial layer (900)
— On réalise une lithographie, suivie d'une gravure de la couche de Si02 (901) afin de réaliser un masque de gravure de tranchées (902) dans la couche sacrificielle (900).- A lithography is carried out, followed by an etching of the layer of Si02 (901) in order to produce an etching mask for trenches (902) in the sacrificial layer (900).
— On dépose une couche conductrice (903), et on comble par électrolyse les tranchées (902).- A conductive layer (903) is deposited, and the trenches (902) are filled by electrolysis.
— On grave la couche conductrice sur la surface de la couche de Si02 (901) afin de réaliser un second niveau d'interconnexions du second ensemble d'électrodes verticales.- The conductive layer is etched on the surface of the Si02 layer (901) in order to produce a second level of interconnections of the second set of vertical electrodes.
— On grave la couche de Si02 (901) afin de faire un masque à la gravure profonde de la couche (900) pour réahser une tranchée (1001) ayant la forme de la membrane périphérique (500).- The Si02 layer (901) is etched in order to make a mask with a deep etching of the layer (900) in order to re-create a trench (1001) having the shape of the peripheral membrane (500).
— On comble la tranchée (1001) par un matériau élastomère à l'aide d'une raclette, ou par centrifugation.- The trench (1001) is filled with an elastomeric material using a squeegee, or by centrifugation.
— On dépose une couche de Si02 épaisse (1003) que l'on grave sélectivement sous la forme d'une grille. On grave par gravure ionique réactive la couche (900) au travers des trous de la grille de Si02, puis on élimine par dissolution chimique la totahté de la couche sacrificielle (900) — On colle sur la grille de Si02, une membrane d'étanchéité — On élimine la couche sacrificielle (801) pour hbérer tous les micro-actionneurs réalisés sur le substrat (800). - A thick layer of Si02 (1003) is deposited which is selectively etched in the form of a grid. We engrave by ion etching reactivates the layer (900) through the holes in the Si02 grid, then the total amount of the sacrificial layer (900) is eliminated by chemical dissolution - We glue a sealing membrane to the Si02 grid - We eliminate the layer sacrificial (801) to host all the micro-actuators produced on the substrate (800).
PCT/FR2000/003596 2000-01-13 2000-12-19 Micro actuator with optimised deformable structure for disc storage and method for making same WO2001052399A1 (en)

Applications Claiming Priority (2)

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FR0000403A FR2803957B1 (en) 2000-01-13 2000-01-13 CAPACITIVE MICRO ACTUATOR WITH OPTIMIZED DEFORMABLE STRUCTURE FOR DISK MEMORY AND MANUFACTURING METHOD
FR00/00403 2000-01-13

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1398766A2 (en) * 2002-08-13 2004-03-17 Lg Electronics Inc. Micro-actuator, manufacturing method thereof, optical pickup head of optical recording/reproducing apparatus with micro-actuator and fabrication method thereof
CN100466076C (en) * 2002-08-13 2009-03-04 Lg电子株式会社 Micro-driving mechanism and method for manufacturing the same,Optical pickup head and method for manufacturing the same

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5642015A (en) * 1993-07-14 1997-06-24 The University Of British Columbia Elastomeric micro electro mechanical systems
US5982585A (en) * 1997-12-30 1999-11-09 International Business Machines Corporation Rotary electrostatic microactuator with optimum flexure arrangement
EP0978832A2 (en) * 1998-07-29 2000-02-09 Hewlett-Packard Company System and method for forming electrostatically actuated data storage mechanisms

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5642015A (en) * 1993-07-14 1997-06-24 The University Of British Columbia Elastomeric micro electro mechanical systems
US5982585A (en) * 1997-12-30 1999-11-09 International Business Machines Corporation Rotary electrostatic microactuator with optimum flexure arrangement
EP0978832A2 (en) * 1998-07-29 2000-02-09 Hewlett-Packard Company System and method for forming electrostatically actuated data storage mechanisms

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
KIM B -H ET AL: "MEMS FABRICATION OF HIGH ASPECT RATIO TRACK-FOLLOWING MICRO ACTUATOR FOR HARD DISK DRIVE USING SILICON ON INSULATOR", ORLANDO, FL, JAN. 17 - 21, 1999,NEW YORK, NY: IEEE,US, 1999, pages 53 - 56, XP000830721, ISBN: 0-7803-5195-9 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1398766A2 (en) * 2002-08-13 2004-03-17 Lg Electronics Inc. Micro-actuator, manufacturing method thereof, optical pickup head of optical recording/reproducing apparatus with micro-actuator and fabrication method thereof
EP1398766A3 (en) * 2002-08-13 2005-08-17 Lg Electronics Inc. Micro-actuator, manufacturing method thereof, optical pickup head of optical recording/reproducing apparatus with micro-actuator and fabrication method thereof
US7263039B2 (en) 2002-08-13 2007-08-28 Lg Electronics Inc. Micro-actuator, manufacturing method thereof, optical pickup head of optical recording/reproducing apparatus with micro-actuator and manufacturing method thereof
CN100466076C (en) * 2002-08-13 2009-03-04 Lg电子株式会社 Micro-driving mechanism and method for manufacturing the same,Optical pickup head and method for manufacturing the same

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