JP2682181B2 - Micro movable mechanical mechanism - Google Patents

Micro movable mechanical mechanism

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Publication number
JP2682181B2
JP2682181B2 JP2023684A JP2368490A JP2682181B2 JP 2682181 B2 JP2682181 B2 JP 2682181B2 JP 2023684 A JP2023684 A JP 2023684A JP 2368490 A JP2368490 A JP 2368490A JP 2682181 B2 JP2682181 B2 JP 2682181B2
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electrode
movable
mechanical mechanism
movable mechanical
fixed
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JPH03230779A (en
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健一郎 鈴木
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日本電気株式会社
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Priority claimed from US08/052,272 external-priority patent/US5428259A/en
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Description

Description: TECHNICAL FIELD The present invention relates to a micro movable mechanical mechanism, and particularly to a micro and highly accurate vibration type sensor, a high performance micro robot actuator, a magnetic disk or an optical disk head, and the like. The present invention relates to a device used as a micro movable mechanism.

(Prior Art) Currently, the micro movable mechanical mechanism used in the above fields is mainly manufactured by a machining technology such as lathe processing. Due to the dramatic progress of the machining technology, the precision is relatively low and the accuracy is low. It is possible to make a good one. However, the progress on the system side is more rapid, and there is a demand for higher performance. For this reason, it is becoming difficult to deal with this in extension of conventional machining, and the present situation is that the emergence of innovative machining techniques is expected. Less than,
This will be explained by taking a magnetic or optical disk head as an example.

At present, the detection portion of a head for reading a recording medium manufactured with high density is very finely processed. However, in order to move it on the recording medium, the detection part is mounted on an arm made of metal of about several cm, and the head reading part of the head is driven with an accuracy of about 15 to 30 μm using servo technology. ing. This drive pitch is limited by the natural frequency of the machine. The natural frequency of the machine increases as the size of the moving machine decreases, and as a result, the machine can be driven at high speed. By combining this with servo technology, it is possible to make even smaller movements. Become. However, with the current structure in which the detection part is mounted on a metal arm, it is difficult to reduce the size of the entire machine due to the difficulty of mounting minute parts even if individual parts are made finer. It was going on. On the other hand, advances in the technology of recording media are now making it possible to record signals at a pitch of approximately μm or less. Therefore, in the field of recording signals, it can be seen that the size of the drive mechanism system of the head is the biggest obstacle in achieving high density.

Although no report has been made yet on realizing the miniaturization of the head described above by a method different from the extension of the conventional technology, recently, an innovative technology that can be expected to be able to realize this is the silicon vibration type. Published in connection with sensor technology. In the following, this technique will be introduced, and its problems and solutions will be shown, after which it will be shown that a fine head can be manufactured by applying this technique.

Figure 9 shows the Proceedings of IEEE Micro.
W Seen Tongue (WCTa), pages 53-59 of Electro Mechanical Systems (February 1989)
ng) et al., “Laterally Driven Polysilicon Resonan
FIG. 3 is a top view of a vibration sensor quoted from “t Microstructures”. All these structures consist of polysilicon deposited on the surface of a silicon substrate. In the figure, the fixed electrode 11
A fixed base 13 connected to a and 11b and a support base 14 connected to the folded beam 15 are made in close contact with the silicon substrate. The fixed electrodes 11a and 11b and the movable electrode 12 connected to the folded beam 15 are supported by a fixed table 13 and a supporting table 14 in a state of floating above the silicon substrate. The fixed electrodes 11a, 11b and the movable electrode 12 are each formed in the shape of a comb tooth and dig into each other by about 1/3. This vibration sensor has three voltage supply pads. The pad 17 and the pad 18 are for applying an electric potential to the fixed electrodes 11a and 11b in the same drawing, respectively, and are applied in a mutually opposite phase and crosswise between the supply potential and the ground. On the other hand, the ground potential is always applied to the pad 16, and the ground potential is applied to the movable electrode 12 via the support 14 and the folded beam 15. Since the pad 18 becomes the ground when the pad 17 has a certain supply potential, the movable electrode
12 is attracted to the fixed electrode 11a by electrostatic force and moves upward in the figure. Then, when the potential of the pad 17 changes to the ground and the potential of the pad 18 becomes a voltage other than the ground at the same time, the movable electrode 12 is attracted downward in the figure and moves downward. When the voltage of the pads 17 and 18 is changed at a cycle close to the natural frequency of the movable electrode 12, the movable electrode 12 vibrates greatly. The natural frequency of the movable electrode 12 is a function of the atmospheric pressure around the movable electrode 12 when the structure is fixed. Therefore, the pressure of air or the like can be detected by detecting the natural frequency, which can be used as a sensor. The shape of the folded beam 15 changes due to the movement of the movable electrode 12, and the force of this distortion tends to return the movable electrode 12 to the original position. Therefore, the moving distance of the movable electrode 12 is a function of not only the applied voltage but also the rigidity of the folded beam 15.

This vibration type sensor made of polysilicon can be made very minute. FIG. 10 shows a method for manufacturing the vibration sensor described in the above document. Hereinafter, a method of manufacturing the vibration sensor will be described with reference to FIG. After depositing the oxide film 21 and the nitride film 22 on one main surface of the silicon substrate 20, the separation window 23 between the fixed electrode and the movable electrode is patterned (FIG. 7A). Polysilicon electrode 25 deposited and patterned to connect to pad 16 in the previous figure
Then, a polysilicon electrode 24 connected to the pad 17 or the pad 18 is formed (FIG. 7B). The PSG film 26 is deposited and patterned (FIG. 7C), and the second polysilicon film 27 is formed.
Then, the second PSG film 28 is deposited (FIG. 7D). The PSG film 28 is patterned, the polysilicon film 27 is patterned using the PSG film 28 as a mask, and then the PSG film 28 is removed (FIG. 7E). The PSG film 26 is removed by immersing this sample in a hydrofluoric acid solution for a long time ((f) of the same figure). As shown in FIG. 3F, the second polysilicon film 27 is formed by fixing the fixed electrode 11a,
11b and the movable electrode 12, these electrodes are the silicon substrate 20
The structure is lifted from. The thickness of the electrodes 11a, b, 12 is 2
It is about μm. Further, the fixed base 13 of the previous figure is shown in FIG.

As shown above, since the movable machine made of polysilicon can be manufactured by the silicon IC process,
A minute thing can be manufactured. In addition, silicon
By patterning by IC process, mechanical elements with different shapes can be manufactured at the same time on the same silicon substrate,
There is no need to assemble the individual parts as in conventional machining. At the moment, only the vibration type sensor described above has been announced as a specific application, but it is possible to apply this technology to manufacture a magnetic or optical head as shown below. .

(Problems to be Solved by the Invention) However, since the above-described conventional technique uses the deposited polysilicon thin film as a mechanical element, the following problems occur.

(1) When a polysilicon thin film is deposited by a sputtering apparatus, a long time is required to produce a thick film because the deposition rate is low. In a normal IC process, the thickness of the polysilicon film is up to about 1 μm. Of course, a thicker film can be formed if long-term growth is acceptable. However, at that time, the cost of the device increases because the expensive device is occupied for a long time. To make matters worse, a large internal stress is generated inside the thick polysilicon thin film, which causes the substrate to warp or crack. Furthermore, when the polysilicon thin film is finally separated from the silicon substrate as in this example, the polysilicon structure is deformed due to internal stress, and the polysilicon structure warps up or down and contacts or adheres to the silicon substrate. And so on. Many of these troubles have already been reported at a thickness of about 1 μm. For example, Digest of The 4th Internatio
nal Conference on Solid-State Sensors and Actuator
s) (June 1987), "Microfabricated Structures" by SDS Centuria.
for the Measurement of Mechanical Properties and
Adhesion of Thin Films "(pages 11-16). These experiences show that it is not easy to produce a polysilicon thin film having a uniform internal stress.

(2) In reality, it is not easy to form a thick polysilicon thin film as described in (1) above. However, it is advisable to increase the thickness of the polysilicon as described below.

The movable electrode of the vibration type sensor of the conventional example vibrates by the electrostatic force caused by the potential difference between the movable electrode and the fixed electrode. This electrostatic force is proportional to the cross-sectional area of the electrode surfaces facing each other. Therefore,
When the cross-sectional area is small (thickness of about 1 μm), it is necessary to apply a large voltage to obtain a sufficient electrostatic force.
In the previous example, the movable electrode could be moved relatively efficiently in order to move it near the natural frequency. However, when operating at a frequency away from the natural frequency, a voltage of 200V to 350V is required. This voltage is used in normal ICs 10
It is very large compared to the voltage of about V, and there is a drawback that the whole device becomes large because it requires a booster coil in addition to the normal voltage when trying to drive this machine. Therefore, if the movable electrode and the fixed electrode can be thickened, for example, if a thin film of about 10 μm can be formed, the applied voltage can be reduced to 1/10, which is very desirable.

(3) Although mechanical properties such as internal stress and mechanical constants of polysilicon are being energetically researched at present, it is strongly dependent on the process conditions at the time of formation, and it is still difficult to design the structure of micromachines. There is not enough data accumulated. For this reason, it was not possible to precisely and optimally design the machine before fabrication.

The above difficulties are problems inherent in the conventional micro movable machine made of polysilicon, and a new machine structure and a manufacturing method for realizing the same have been urgently desired.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to provide a minute movable machine using a substance instead of polysilicon, and a manufacturing method and a driving method thereof.

(Means for Solving the Problem) The micro movable machine of the present invention is characterized in that, in the mechanism in which the movable electrode is moved by the electrostatic force applied to the fixed electrode, at least one electrode is made of a single crystal semiconductor. As an example of the micro movable machine of the present invention, there is one in which a fixed electrode and a movable electrode are arranged in the shape of a comb tooth which is intertwined with each other. In addition, there is an arrangement in which the distance between the electrodes is changed as the one electrode is separated from the other electrode.

A method of manufacturing a micro movable machine of the present invention is a method of manufacturing a mechanism in which a movable electrode is moved by an electrostatic force applied to a fixed electrode, wherein at least one fixed electrode or a movable electrode pattern is formed on one main surface of a semiconductor substrate. After that, the side on which the pattern of the semiconductor substrate is formed is attached to another substrate, and the electrode pattern is separated from the semiconductor substrate. As a method of forming an electrode pattern, there is a method of forming a silicon substrate in which boron is diffused at a high concentration, a method of diffusing an impurity of a type different from that of a semiconductor substrate and forming the same there.

The driving method of the micro movable machine of the present invention is a mechanism in which the movable electrode is moved by the electrostatic force applied to the fixed electrode,
It is characterized in that the movable electrode is moved by sequentially scanning the voltage of the teeth of the fixed electrode.

Further, a thin film head or an optical head can be mounted on the micro movable machine of the present invention.

(Operation) In the micro movable mechanical mechanism of the present invention, the movable electrode or the fixed electrode is made of a single crystal semiconductor. Single crystals, unlike deposited polysilicon thin films, have the advantage that their mechanical properties are uniform, their internal stresses are small, and that a wealth of well-known data can be used. On the other hand, single-crystal substrates usually had the difficulty of being too thick to make a micro movable machine, but as described in the manufacturing method of the present invention, by thinning the single-crystal substrate with patterned movable electrodes, It became possible to make machines. At this time, since the single crystal substrate is attached to another substrate before thinning, the single crystal substrate does not separate into individual components even after etching, and does not require labor for assembling a micro machine. Further, by devising the structure of the fixed electrode and the movable electrode of the micromachine which can be easily manufactured by the present invention and the driving method of the electrostatic force applied between both electrodes, The control becomes precise.

(Example) A structure when a vibration type sensor similar to the conventional example is manufactured using the present invention will be described with reference to FIG. FIG. 1 is the same as the drawing used in the description of the prior art example except for some parts, but the structure such as the material is completely different. In the figure, the same reference numerals as those in the conventional example indicate the elements having the same operation.

In FIG. 1, the fixed electrodes 11a and 11b and the movable electrode 12 have a thickness of 10 μm.
It is made of a single crystal of silicon and has a structure floating from the glass substrate 1. The movable electrode 12 is a folded beam made of single crystal silicon floated from the substrate by the support 14.
It is supported on the glass substrate 1 via 15. on the other hand,
The fixed electrodes 11a and 11b are supported by a fixed base 13 made of silicon. Since the fixed electrodes 11a and 11b, the movable electrode 12, the folded beam 15, the fixed base 13, and the support base 14 are all made of the same silicon substrate, their mechanical properties are very close to each other. Furthermore, each internal structure also has uniform mechanical properties and has a small internal stress. Pads 17 and 1 for supplying electric potential to the fixed electrodes 11a and 11b and the movable electrode
6, 18 are produced by selectively forming a metal on a glass substrate. These metal electrodes are in contact with and electrically connected to a part of the fixed base 13 and a part of the support base 14. The metal electrode is usually composed of a plurality of metals such as chromium-gold, titanium-platinum-gold and the like. By increasing the size of the ground electrode 2 communicating with the pad 16 so as to spread around the movable electrode 12 as shown in the figure, the potential of the electrode is fixed,
External noise is reduced. Fixed electrode as shown in the figure
11a and 11b and the movable electrode 12 are arranged intricately in the shape of comb teeth similar to each other. A ground potential is applied to the movable electrode 12 from the pad 16 through the ground electrode 2. On the other hand, a two-phase AC potential of a potential equal to the ground potential and a different potential (about 10 V) is applied to the fixed electrodes 11a and 11b.
1a and 11b are driven to have opposite phases. The movable electrode 12 does not generate a force between the movable electrode 12 and the fixed electrode on the side of the ground potential, but generates an electrostatic attractive force proportional to the potential difference between the movable electrode 12 and the other fixed electrode. Therefore, the movable electrode moves to the side of the fixed electrode that is different from the ground potential, and this state is alternately switched between 11a and 11b, so that the movable electrode vibrates in proportion to this switching speed. Since the thickness of the fixed and movable electrodes is 10 μm, which is thicker than before, it vibrates sufficiently even if the AC potential is as low as about 10V. When the electric potential is switched at a frequency close to the natural frequency of the system composed of the movable electrode 12, the folded beam 15 and the support 14, the movable electrode 12 vibrates with the largest amplitude. In the embodiment of FIG. 1, all electrodes were made of single crystal Si. However, one of the electrodes may be polysilicon. For example, fixed electrodes 11a, b
1 μm thick polysilicon, movable electrode 12 10 μm thick
When single crystal Si is used, the lines of electric force generated between the two are parallel to each other as compared with the case of polysilicon, so that the design and the like are easier.

Since this embodiment is driven by electrostatic force, a large electric field is generated in a small area. Therefore, if the device is exposed to a poor environment such as high humidity, current leakage through the glass surface occurs between different metal wirings, which becomes a problem. For this reason, after patterning the metal wiring, an insulating film such as an oxide film or a nitride film is deposited on the metal wiring by sputtering or the like, so that a leak current through the glass substrate can be reduced. Furthermore, it is worth noting that this embodiment is provided on a glass substrate. Unlike the silicon substrate, the glass substrate is a perfect insulator, so it is possible to completely ignore the influence on the electric force lines of the substrate that occurs during driving, and only the electric force line between the fixed electrode and the movable electrode can be ignored. The device can be designed with only consideration, which helps to significantly simplify the analysis and scaling of the device.

Although the structure in which the silicon substrate is attached to the glass substrate is described in this embodiment, it may be attached to the silicon substrate. At this time, since the silicon substrate is an imperfect insulator compared to glass, there is a disadvantage that the electric lines of force in the device are complicated, but on the other hand, irregularities are easily formed in the silicon substrate. Because it is possible, a complicated structure different from that of the present embodiment can be made. For example, a fixed electrode may be formed on one silicon substrate and a movable electrode may be formed on the other silicon substrate according to the production method of the present invention, and these substrates may be bonded by a silicon-silicon direct bonding method. .

2 (a)-(c) describe a new method for making the structure of FIG. FIG. 2 shows a cross section taken along the line AA ′ in FIG. Oxide film 21 on silicon single crystal substrate 20
Is formed, and high-concentration boron is diffused from the region where the oxide film 21 is partially removed to form the boron diffusion layer 3 (FIG. 7A). The oxide film 21 is removed from the entire surface, the oxide film 29 is provided again, and the oxide film 29 is partially removed. Then, the boron diffusion layer 3 is etched using the oxide film 29 as a mask to reach the silicon substrate 20 to form the trench groove 4. ((B) of the same figure). This trench groove 4 is dry-etched RIE (Reactive Ion Etching)
By using, it is possible to produce an arbitrary cross-sectional shape such as a circle. In the case of mutually orthogonal shapes such as the shape shown in FIG. 1, the surface orientation of the silicon substrate 20 is selected as (110) and the wet etching technique using an anisotropic etching solution such as EDP (ethylenediaminepyrocatechol) is used. Also, it is possible to form the trench groove 4 surrounded by the vertical wall as shown in FIG. The oxide film 29 is patterned to form the oxide film 30, and the boron diffusion layer 3 and the silicon substrate 20 are etched using this as a mask as shown in FIG. The fixed electrode 31 and the movable electrode 32 are formed by these three mask steps. Then, the oxide film 30 is removed and the fixed electrode 31 is bonded to the glass substrate by the electrostatic bonding method. Although not shown in the figure, the movable electrode 32 is supported on the glass substrate via a support table provided in a direction perpendicular to the figure. On this glass substrate, a composite metal layer such as chromium-gold or titanium-platinum-gold, which will be the pad and the ground electrode in FIG. 1, is selectively patterned in advance. Conduction between the fixed electrode and the movable electrode composed of the metal layer and the boron diffusion layer is performed by physically pressing the boron diffusion layer against the metal layer by using the bonding force between silicon and glass. do not need. Finally, the sample in which silicon and glass are adhered is dipped in an etching solution such as EDP to remove the silicon substrate 20. An etchant such as EDP has a property of dissolving a silicon substrate except for a layer in which boron is diffused at a high concentration, and further, a glass substrate and a metal such as gold remain without being dissolved in the etchant. The thickness of the fixed electrode and the movable electrode can be easily changed from about 1 μm to several tens of μm by changing the boron diffusion temperature and the time in the manufacturing method described above. At this time, since the boron diffusion layer is made of single crystal silicon, its mechanical properties are uniform and the internal stress is small, which is a major feature of this structure. Therefore, even when a thick fixed electrode or a movable electrode is manufactured, the shape does not warp unlike the conventional polysilicon thin film.
Furthermore, since the conventional manufacturing method requires one more mask process for contacts other than the one illustrated above,
Whereas a total of 5 mask steps are required, the fabrication method of the present invention only requires 3 mask steps for silicon and 1 mask step for the glass substrate. For this reason, the manufacture is significantly facilitated. Although boron is diffused first in this embodiment, the order is changed to (b) and (c) in the figure.
After that, diffusion (a) of boron may be performed. Further, the order of the steps (b) and (c) in the drawing may be reversed.

In addition to stopping the etching of silicon by the high-concentration boron diffusion used in the present manufacturing method, an electrochemical etch stop method of stopping the etching by applying an electrostatic voltage to a layer in which impurities different from the silicon substrate are diffused is also effective. To perform this method, for example, 3 in FIG. 2 may be an n-type diffusion layer and the substrate may be a p-type. In order to make the entire impurity layer at which etching stops at an equipotential, for example, a metal wiring of a glass substrate is short-circuited outside the device, and after silicon etching is completed, for example, when cutting into chips It is necessary to take measures such as cutting the external short part at the same time.

FIG. 3 shows another embodiment of the present invention. In the figure, the components having the same numbers as the components in FIG. 1 indicate the same components. The structure of FIG. 3 is the same as that of the embodiment of FIG. 1 except for the structure of the fixed electrode 11. Fixed electrode in this example
The width of the teeth of the electrodes 11a and 11b is increased toward the fixed base 13, that is, the distance between the electrodes is reduced as the distance from the movable electrode 12 is increased. As described in the embodiment of FIG. 1, the force acting on the movable electrode 12 is the fixed electrode.
Proportional to the potential applied to 11. On the other hand, this electrostatic force is also proportional to the distance between the fixed electrode and the movable electrode. In the case of the embodiment shown in FIG. 1, since the distance between the fixed electrode and the movable electrode is constant, the electrostatic force acting per unit length of the movable electrode is constant regardless of the movement of the movable electrode. When the distance between the fixed electrode and the movable electrode changes due to the movement of the movable electrode as in the embodiment, the electrostatic force acting on the movable electrode per unit length also changes accordingly and is inversely proportional to the distance between both electrodes. Increase. Therefore, the movable electrode tends to move further toward the back of the fixed electrode. This embodiment has the advantage that it can be driven with a smaller force than in the case of FIG. The movement of the movable electrode in the direction of the fixed electrode causes the folded beam 15 to move.
The force of the opposite direction due to the stiffness of the balances the balance and eventually stops. This movement can be changed by changing the structural elements such as the width of each tooth of the fixed electrodes 11a and 11b and the rigidity of the folded beam, which has the advantage of increasing the degree of freedom in design as compared with the structure of FIG. I understand. Although the width of the teeth on the fixed electrode side is changed in this embodiment, the same effect can be obtained by changing the width of the teeth on the movable electrode side. Furthermore, changing both the fixed electrode side and the movable electrode side is also included in the present invention.

FIG. 4 shows another embodiment of the present invention. Components having the same numbers as those in FIG. 1 indicate the same components. In this embodiment, the movable electrode 40 and the fixed electrodes 41a and 41b on both sides thereof are arranged in the lateral direction, and unlike the embodiment of FIG. 1, they are not invading each other. Further, as shown in the figure, the movable electrode 40 and the fixed electrode 41 are
The tooth pitches of a and b are different. In the embodiment shown in the figure, the tooth positions of the movable electrode 40 and the fixed electrodes 41a, 41b coincide with each other at four positions, respectively, in the upper and lower directions indicated by the arrows in the figure. The folding beams 44, which are located on the left and right sides of the movable electrode 40 and have one end fixed to the movable electrode 40, are supported in a floating state from the substrate by a support table 42 fixed to the glass substrate 1, and the movable electrode 40 is supported by the substrate. Is lifted from. On the other hand, also in the central portion of the movable electrode 40, the linear beams 43 and 47 and the connecting plate 45 are
The movable electrode 40 is supported from the substrate by the buffer mechanism 48 consisting of. In addition to supporting the buffer mechanism 48 and the movable electrode 40 described above for the folded beam 44, it has the following two functions. First, when the movable electrode 40 moves to the left and right in the figure, the restoring force generated by the deformation of the folded beam 44 and the linear beam 43 suppresses this movement and tries to return the movable electrode 40 to its original position. Secondly, since the buffer mechanism 48 and the folding beam 44 are fixed to the substrate via the support 42 at one end thereof, the influence of stress such as heat and humidity generated from the contact surface between the substrate and the support is not affected. It is possible to reduce the transmission to the movable electrode. Further, the repeating structure of the folded beam 44 and the structure in which the linear beams 43 are orthogonal to each other through the movable connecting plate 45 as shown in the figure have a buffer mechanism 48 and a shape of the folded beam 44 that suppress the influence of stress inside the beam. Helps to mitigate by changing.

In the embodiment of the present invention, the movable electrode 40 moves in the left-right direction in the drawing according to the change in the voltage applied to the fixed electrodes 41a and 41b.
A slider protrusion 46 fixed to the substrate 1 is provided to limit this movement to the left and right one dimension. If the movable electrode 40 deviates from the one-dimensional movement in the left and right direction and moves in the vertical direction in the figure, it contacts the slider protrusion 46 and is prevented from moving in the vertical direction.

Different voltages can be applied to the teeth of the fixed electrodes 41a and 41b independently, but in the embodiment shown in FIG.
The teeth of the fixed electrodes 41a and 41b facing each other across the 40 are selected so as to have the same potential, and a potential different from the potential of the movable electrode 40 is applied. At this time, the same potential as that of the movable electrode is supplied to the teeth of the other fixed electrodes. In the embodiment shown in the figure, the interval between every 6 teeth of the fixed electrodes 41a and 41b and the interval between every 5 teeth of the movable electrode 40 are designed to match. Since an electrostatic force works only between the teeth of the fixed electrode and the movable electrode to which different potentials are applied, the voltage of the fixed electrode 41a, b of the movable electrode 40 is applied to the tooth position of the fixed electrode 41b from the condition of force balance. The movable electrode 40 moves to the position where the teeth match. By sequentially scanning the teeth of the fixed electrodes adjacent to each other with the applied voltage, it becomes possible to move the movable electrodes in the scanning direction.

In addition, the displacement of the movable electrode can be detected by detecting the position of the movable electrode 40 on the fixed electrode side. For example, a circuit for detecting the electric capacitance between the teeth of the fixed electrode and the teeth of the movable electrode to which the driving voltage is not applied, or a means for emitting a laser toward the movable electrode on the fixed electrode side and detecting reflected light thereof is provided. There is a method such as providing. By feeding back the signal indicating the position of the movable electrode to the drive circuit on the fixed electrode side, the movement control of the movable electrode can be made more precise.

FIG. 5 shows another embodiment of the present invention. Components having the same numbers as those in FIG. 4 indicate the same components. In the embodiment shown in the figure, the structure of the fixed electrode is the fourth.
It differs from the embodiment of the figure. In this embodiment, the fixed electrode 51 is provided on the silicon substrate (not shown) side, and the fixed electrode 5 is provided on the glass substrate 1 side.
Two electrodes are provided. There is a space between the glass substrate 1 and the silicon substrate, and the movable electrode 40 moves there. The teeth 55 of the movable electrode 40 are located between the fixed electrodes 51 and 52, and move when an electric potential is applied. The same voltage is applied to the teeth of the fixed electrodes which are vertically opposed to each other, and the movable electrode 40 is moved left and right by the same driving method as described in the embodiment of FIG. At this time, the minimum distance that the movable electrode moves is determined by the pitch of the fixed electrodes. The movable electrode 40 is a fixed electrode not only in the surface direction of the glass substrate 1 but also in the direction opposite to the movement of the wave in order to minimize it.
It is also possible to apply a potential difference between 51 and 52. FIG. 6 shows the BB 'cross section of FIG. 5, and FIG. 7 shows the method of making the CC' cross section of FIG. Elements having the same numbers in FIG. 2 as those in FIG. 2 indicate the same elements. First, the deep groove 4 is opened (FIGS. 6 and 7 (a)), and subsequently, the support table (not shown) and the fixing table 31 are left to be shallowly etched (FIG.
6,7 (b)). Finally, the boron is diffused and the movable electrode 40
(FIG. 6) and the fixed electrode 51 (FIG. 7) are formed. The fixed electrode 52 is formed of metal (not shown) on the glass substrate, the silicon substrate and the glass substrate are bonded by electrostatic bonding, and the region where boron is not diffused is removed by wet etching. The end side flat portions 53 and the central flat portion 54 located at both ends of the movable electrode 40 shown in FIG.
It is also a feature of the present embodiment that these flat portions do not come into contact with the slider protrusions 46 even when the right and left are moved, and the operating range of the movable electrode 40 can be widened.

FIG. 8 shows a sectional view of another embodiment of the present invention. In the configuration of the figure, those having the same numbers as in FIG. 5 indicate the same elements. The embodiment shown in this figure differs from the embodiment shown in FIG. 5 in the structure of the fixed electrode. The silicon-side fixed electrode 51 and the glass substrate-side fixed electrode 52 are arranged so as to be offset from each other by about 1/2 of the pitch width, and a voltage is applied to the fixed electrode in the order of silicon side-glass side-silicon side. It At this time, the movable electrode 40 moves so as to match the applied tooth positions of the fixed electrode. This structure has the advantage that the movable electrodes can be controlled with an accuracy of half the pitch of the fixed electrodes. In addition to the above-described embodiment, a fixed electrode may be further added at the same height position as the movable electrode as in the embodiment of FIG. 4, and the fixed electrode may be driven in the order of upper side, side surface, lower side of the movable electrode. Included in the invention. At this time, the movable electrodes can be driven with an accuracy of 1/3 of the pitch of the teeth of the fixed electrodes by arranging the fixed electrodes so as to be displaced by about 1/3 of the width.

The structure, manufacturing method, and driving method of the linear actuator that can move in one dimension have been described above. This actuator can be used as it is as the vibration type sensor described in the conventional example. Further, a thin film head made of a magnetic material such as ferrite is formed on the central flat surface in the movable electrode 40 shown in FIG. 4 or the central flat portion 54 in the movable electrode 40 shown in FIGS. 5 and 8 by a known method. A minute magnetic head can be manufactured by depositing and patterning. As a method of manufacturing this thin film head, a method of directly writing on a device by using a technique such as photo-CVD is also included in the present invention. Further, by mounting an optical fiber or a light emitting element and a light receiving element, it is possible to configure a minute optical head. In the embodiment of the present invention, the method of driving by electrostatic force has been described. However, the present invention also includes a method of driving the movable electrode by electromagnetic force by forming the fixed electrode with a coil or the like. Further, the actuator of this embodiment is not limited to the one that moves on a straight line, but can be easily applied to an actuator that moves in an arc shape. At this time, the fixed electrodes are arranged in an arc around the movable electrode having an arc shape.

In the above-described example, the single-crystal Si forming the electrodes is all formed from a Si substrate. However, the present invention is not limited to this, and vapor phase epitaxy ( It is clear that single crystal Si formed by laser annealing or the like may be used.

Further, in the examples shown in FIGS. 3 to 8 and the modifications thereof, the electrodes are all single crystal semiconductors, but one or all of the electrodes may be polysilicon.

(Effects of the Invention) Since the micro movable mechanical mechanism of the present invention comprises the constituent elements of the single crystal semiconductor, the drawbacks of the structure of the conventional polysilicon thin film are remarkably improved. The ability to vary greatly the thickness of the components has facilitated fabrication and actuation. Further, even if the thickness is increased, internal stress is not generated, so that the change in shape such as warpage can be reduced.

By using the manufacturing method of the present invention, the device can be manufactured with fewer mask steps than in the conventional example, and the yield of the device can be significantly improved. In the structure of the present invention, a single crystal semiconductor substrate is attached to another substrate and manufactured. If a glass substrate is selected as the other substrate, the electric field lines inside the device can be easily analyzed, and the device design can be significantly simplified. When a thin film magnetic head is formed on this actuator made of a single crystal semiconductor, it is possible to realize a head for a magnetic disk which operates very minutely and operates at high speed. Further, when the optical element is mounted on the actuator, a very high performance optical disk head can be realized. By using these disk heads, it is apparent that writing and reading of the disk can be performed with a density of about 100 times higher than that of the conventional example, and it will be a great contribution to downsizing of the disk device.

[Brief description of the drawings]

1 is a top view of an embodiment of the first invention of the present application, FIG. 2 is a cross-sectional view of an embodiment of the manufacturing method of the present invention, FIG. 3, FIG.
FIG. 5 and FIG. 5 are top views of other embodiments of the present invention, and FIG.
FIG. 7 and FIG. 7 are sectional views of the manufacturing method of the embodiment of the present invention shown in FIG. 5, and FIG. 8 is a sectional view of another embodiment. Further, FIGS. 9 and 10 show a top view of a conventional structure and a cross-sectional view of a manufacturing method thereof. 1 ... Substrate, 2 ... Ground electrode, 3 ... Boron diffusion layer, 4 ... Trench groove, 11 ... Fixed electrode, 12 ... Movable electrode, 13 ... Fixed base, 14 ... Support base, 15 ... … Folded beam, 16,17,18 …… Pad, 20 …… Silicon substrate, 21 ……
Oxide film, 22 …… Nitride film, 23 …… Separation window, 24,25 …… Polysilicon electrode, 26 …… PSG film, 27 …… Second polysilicon film, 28 …… Second PSG film, 29,30… … Oxide film, 31 …… fixed electrode, 32 …… movable electrode, 40 …… movable electrode, 41 …… fixed electrode, 42 …… support base, 43 …… straight beam, 44 …… folded beam, 45 …… connection Plate, 46 …… Slider protrusion, 47 ……
Linear beam, 48 ... Buffer mechanism, 51 ... Fixed electrode (silicon side), 62 ... Fixed electrode (glass substrate side), 53 ... Edge flat part, 54 ... Central flat part

Claims (20)

(57) [Claims]
1. A micro movable mechanical mechanism in which a movable electrode is moved by an electrostatic force applied to a fixed electrode, at least 1.
A minute movable mechanical mechanism characterized in that one electrode is made of a single crystal semiconductor in which a concavo-convex shape is directly provided at a position facing the other electrode.
2. The micro movable mechanical mechanism according to claim 1, wherein the fixed electrode and the movable electrode are arranged in the shape of a comb tooth which is intricately interdigitated with each other.
3. A method of manufacturing a micro movable mechanical mechanism in which a movable electrode is moved by an electrostatic force applied to a fixed electrode, wherein after at least one fixed electrode or movable electrode pattern is formed on one main surface of a semiconductor substrate, A method of manufacturing a minute movable mechanical mechanism, characterized in that a side on which a pattern of the semiconductor substrate is formed is attached to another substrate, and the electrode pattern is separated from the semiconductor substrate.
4. The electrode pattern is formed in a silicon substrate in which boron is diffused at a high concentration.
A method for manufacturing the minute movable mechanical mechanism described in [3].
5. The method of manufacturing a micro movable mechanical mechanism according to claim 3, wherein the electrode pattern is formed in a semiconductor substrate in which an impurity type different from the impurity type of the semiconductor substrate is diffused.
6. A micro movable mechanical mechanism in which a movable electrode is moved by an electrostatic force applied to a fixed electrode, at least 1.
One electrode is made of a single crystal semiconductor, fixed electrodes and movable electrodes are arranged in the shape of a comb tooth that interdigitates with each other, and the distance between the electrodes changes as one electrode moves away from the other electrode. A small movable mechanical mechanism.
7. The micro movable mechanical mechanism according to claim 2, wherein the distance between the electrodes is changed as one electrode is separated from the other electrode.
8. The micro movable mechanical mechanism according to claim 1, wherein the fixed electrode and the movable electrode are arranged laterally at different electrode pitches.
9. The fine movable mechanical mechanism according to claim 1, wherein fixed electrodes are provided above and below the movable electrode.
10. The micro movable mechanical mechanism according to claim 1, wherein the movable electrode is supported on the substrate by using a buffer mechanism for reducing the influence from the substrate.
11. A micro movable mechanical mechanism in which a movable electrode is moved by an electrostatic force applied to a fixed electrode, wherein at least one electrode is made of a single crystal semiconductor and a movable mechanism is used which reduces an influence from a substrate. A micro movable mechanical mechanism in which electrodes are supported on a substrate.
12. The micro movable mechanical mechanism according to claim 10, wherein the buffer mechanism is composed of a plurality of beams via a movable connecting plate.
13. Claims 1, 2, 6, 7, 8, 9, 10, 1
The minute movable mechanical mechanism according to any one of 1 and 12,
A minute movable mechanical mechanism characterized in that a fixed electrode and a movable electrode are provided on a semiconductor substrate.
14. Claims 1, 2, 6, 7, 8, 9, 10, 1
The method for driving a minute movable mechanical mechanism according to any one of 1, 12, and 13, wherein the movable electrode is moved by sequentially scanning the voltage of the teeth of the fixed electrode. Mechanism driving method.
15. The movement according to claim 14, wherein the movement of the movable electrode is controlled by detecting the position of the minute movable mechanical mechanism and feeding back the position signal to the fixed electrode drive signal. Driving method of movable mechanical mechanism.
16. A fine movable mechanical mechanism in which a movable electrode is moved by an electrostatic force applied to a fixed electrode, wherein the fixed electrode and the movable electrode are provided on the same insulating substrate. .
17. In a micro movable mechanical mechanism in which a movable electrode is moved by an electrostatic force applied to a fixed electrode, at least one electrode is made of a single crystal semiconductor, and the fixed electrode and the movable electrode are provided on an insulating substrate. A micro movable mechanical mechanism characterized in that
18. In a fine movable mechanical mechanism in which a movable electrode moves by an electrostatic force applied to a fixed electrode, a structure for supporting the movable electrode with respect to the fixed electrode and a movement of the movable electrode in a direction other than the moving direction are limited. And a slider protrusion structure for controlling the micro movable mechanical mechanism.
19. The method according to claim 1, claim 2, or claim 6.
19. A magnetic head comprising a thin film magnetic head mounted on a movable electrode of the minute movable mechanical mechanism according to any one of claims 1 to 13 or claim 16.
20. Claim 1 or claim 2 or claim 6.
19. An optical disk head, wherein an optical fiber or a light receiving element and a light emitting element are mounted on the movable electrode of the micro movable mechanical mechanism according to any one of claims 1 to 13 or 16 to 18.
JP2023684A 1990-02-02 1990-02-02 Micro movable mechanical mechanism Expired - Lifetime JP2682181B2 (en)

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Application Number Priority Date Filing Date Title
JP2023684A JP2682181B2 (en) 1990-02-02 1990-02-02 Micro movable mechanical mechanism
US08/052,272 US5428259A (en) 1990-02-02 1993-04-20 Micromotion mechanical structure and a process for the production thereof
US08/409,990 US5554304A (en) 1990-02-02 1995-03-24 Process for producing a micromotion mechanical structure

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JP2682181B2 true JP2682181B2 (en) 1997-11-26

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US7187100B2 (en) 2004-04-20 2007-03-06 Advanced Numicro Systems, Inc. Dimensions for a MEMS scanning mirror with ribs and tapered comb teeth
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JP3533443B2 (en) 2000-10-05 2004-05-31 独立行政法人産業技術総合研究所 Motion direction conversion mechanism of electrostatic actuator
US7088492B2 (en) 2001-10-11 2006-08-08 Denso Corporation Micro movable mechanism system and control method for the same
US7217587B2 (en) 2004-02-13 2007-05-15 Advanced Numicro Systems, Inc. MEMS scanning mirror with trenched surface and tapered comb teeth for reducing inertia and deformation
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US7187100B2 (en) 2004-04-20 2007-03-06 Advanced Numicro Systems, Inc. Dimensions for a MEMS scanning mirror with ribs and tapered comb teeth

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