JP2002236263A - Electrostatic actuator and mirror array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic actuator which has a large movable range and can control displacement on the basis of an applied voltage. SOLUTION: The electrostatic actuator has a movable beam 102 and a beam supporting part to support the movable beam 102 in a cantilever manner. The movable beam 102 has a plurality of serially connected unit driver elements 110. Each unit driver element 110 has a first electrode supporting part 112, a second electrode supporting part 114, and a spring part 116 which connects them. The plurality of unit driver elements 110 are alternately located in a reverse direction along a direction where the movable beam 102 is extended. The first electrode supporting part 112 includes two earth electrodes 122a and 122b, and the second electrode supporting part 114 includes two drive electrodes 124a and 124b. That is, one unit driver element 110 has a first and second pairs of earth electrodes and drive electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electrostatic actuator and a mirror array using the same.

[0002]

2. Description of the Related Art Conventionally, actuators utilizing electrostatic attraction have been widely used as one of the driving means of a micromachine. As shown in FIG. 60, these actuators include a ground electrode 1402, a drive electrode 1404 disposed opposite to the ground electrode 1402, and a spring 1406 supporting the drive electrode 1404.

The operation of the electrostatic actuator shown in FIG. 60 will be described with reference to FIG. As shown in FIG. 61, when a voltage is applied from the power supply 1412 to the drive electrode 1404 with the ground electrode 1402 grounded, charges 1414 and 1416 having opposite polarities are induced on the surfaces of the ground electrode 1402 and the drive electrode 1404. And charge 1
The drive electrode 1404 is attracted in the direction of the ground electrode 1402 by an electrostatic force acting between the charge 414 and the charge 1416.

The stroke of this electrostatic actuator is restricted by the initial distance between the drive electrode 1404 and the ground electrode 1402. If the initial electrode distance is increased for the purpose of increasing the stroke, the electrostatic force acting between the electrodes becomes smaller. The driving force of the actuator sharply decreases because it decreases in proportion to the square of the electrode interval.

Since the electrostatic force acting between the electrodes is proportional to the square of the applied voltage, the driving electrode 1404 and the ground electrode 1402
By increasing the voltage applied between the electrodes, it is possible to compensate for the decrease in the electrostatic attraction due to the increase in the electrode spacing described above. However, the voltage includes the electrostatic withstand voltage between each electrode or between the wires connected to the electrodes. , The applied voltage cannot be increased without limit. Therefore, the electrostatic actuator shown in FIG. 60 is not suitable for an application requiring a large displacement.

As an electrostatic actuator which has solved such a problem, an actuator having a configuration shown in FIG. 62 has been disclosed (JSME, Robotics and Mechatronics Lecture Meeting '98 (No. 98-4, 1AIV2). -
3)). As shown in FIG. 62, the actuator includes a silicon substrate 1502, an insulating film 1504, a power supply pad 1506, a first drive electrode 1512, a second drive electrode 1514, a third drive electrode 1516, Fourth drive electrode 1518, fifth drive electrode 1518, first spring 1522, second spring 1524, third spring 1526, fourth spring 1528, and fifth spring 1518.
30.

[0007] As shown in FIG.
2 is covered with an insulating film 1504, and a power supply pad 1506 is formed thereon. First drive electrode 1
Reference numeral 512 denotes a cantilever supported by the power supply pad 1506 via a conductive first spring 1522, and the second drive electrode 1
Reference numeral 514 denotes a first drive electrode 1512 via a conductive second spring 1524, and third drive electrode 1516 denotes a second drive electrode 1514 via a conductive third spring 1526.
In addition, the fourth drive electrode 1518 is a conductive fourth spring 15.
28, the fifth drive electrode 1520 is cantilevered to the fourth drive electrode 1518 via a conductive fifth spring 1530.

The springs 1522, 1524, 1526, 15
28 and 1530 are composed of two types of thin films having different residual stresses and have warpage. Therefore, the first to fifth drive electrodes 1512, 1514, 1516, 1
518 and 1520 are supported obliquely with respect to the surface of the silicon substrate 1502 in a state where no voltage is applied, and the driving electrode near the tip is a power supply pad 1506.
It has a larger inclination angle than the drive electrode close to.

As shown in FIG. 63, this actuator applies a constant voltage by a power source 1532 to the silicon substrate 1.
It is driven by applying a voltage between the power supply pad 502 and the power supply pad 1506. When a voltage is applied, the first to fifth drive electrodes 1512, 1514, 1516, 1518, 1520
Then, the same potential is applied to the silicon substrate 1502 at the same time. Thereby, the silicon substrate 1502 and each of the drive electrodes 1512, 1514, 1516, 1518, 1
Between 520, electrostatic attraction acts.

First, the first drive electrode 1512 receiving the largest electrostatic attraction is drawn to the silicon substrate 1502. As a result, the first drive electrode 1512 eventually becomes a silicon substrate 1502 as shown in FIG.
Contacts the entire surface of the insulating film 1504.

The first drive electrode 1512 is formed of an insulating film 1504
When the second driving electrode 1514 which has received the next largest electrostatic attraction when the contact is made entirely with the silicon substrate 15
02, as shown in FIG. 65, and makes overall contact with the insulating film 1504 on the surface of the silicon substrate 1502. After that, similarly, the third drive electrode 1516 and the fourth drive electrode 1518 are sequentially drawn to the silicon substrate 1502 and entirely contact the insulating film 1504 on the surface. Finally, the fifth drive electrode 1520 is attracted to the silicon substrate 1502, and as shown in FIG. 66, entirely contacts the insulating film 1504 on the surface of the silicon substrate 1502.

This electrostatic actuator has a plurality of drive electrodes connected in series via warped springs, so that the drive voltage does not need to be increased.
The displacement has been increased.

[0013]

The characteristics of the electrostatic actuator shown in FIG. 62 are greatly affected by the initial curvature of the spring. Since the initial curvature of the spring depends on the residual stress difference between the two types of thin films that make up the spring,
It is difficult to control this accurately.

The electrostatic attractive force generated between the driving electrode and the silicon substrate does not change linearly with the applied voltage.
The electrostatic attraction depends not only on the applied voltage but also on the electrode spacing. For this reason, it is difficult to accurately control the amount of displacement of the electrostatic actuator by adjusting the voltage applied to the drive electrode, in other words, it is difficult to accurately arrange the drive electrode at a desired position. For this purpose, an element such as a position sensor is separately required. This hinders cost reduction and element miniaturization.

[0015] Further, this electrostatic actuator requires a relatively large flat plate-shaped substrate.
The direction of movement of the drive electrode is restricted to a direction perpendicular to the substrate, that is, one direction approaching the substrate. The range of application is limited.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a main object thereof is to provide an electrostatic device having a large stroke (movable range) and capable of easily achieving accurate displacement control. It is to provide an actuator.

[0017]

SUMMARY OF THE INVENTION The present invention provides, in part,
An electrostatic actuator driven by electrostatic force,
Movable beam, has a beam support portion that supports the movable beam cantilever, the movable beam has a plurality of unit drive elements connected in series, the unit drive element,
It has a pair of electrode support portions, a spring portion connecting the pair of electrode support portions, and at least a pair of electrode elements provided on each of the electrode support portions.

The present invention is also a mirror array driven by electrostatic force, comprising a plurality of movable beams, a beam support for supporting the plurality of movable beams in a cantilever manner, and a free end of each movable beam. A plurality of mirrors provided, each of the movable beams has a plurality of unit drive elements connected in series, and the unit drive elements have a pair of electrode support portions and a pair of electrode drive portions. It has a spring portion for connecting the electrode support portions, and at least a pair of electrode elements provided on each of the electrode support portions.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. First, an electrostatic actuator according to one aspect of the present invention will be described.

[First Embodiment] An electrostatic actuator according to a first embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the electrostatic actuator 100 of the first embodiment includes a movable beam 102
And a beam support 104 that supports the movable beam 102 in a cantilever manner.

As schematically shown in FIG. 2, the movable beam 102 includes a plurality of unit driving elements 1 connected in series.
It has ten. Each of the unit driving elements 110 has a first electrode support 112, a second electrode support 114, and a spring 116 connecting the pair of electrode supports 112 and 114. The plurality of unit driving elements 110 include:
They are alternately arranged in the opposite direction along the direction in which the movable beams 102 extend. The spring portion 116 is a flexible spring that can bend in a direction perpendicular to the direction in which the movable beam 102 extends.

As shown in detail in FIGS. 3 and 4, the first electrode support portion 112 has two ground electrodes 122a and 122a.
2b, and the second electrode support 114 includes two drive electrodes 124a and 124b. In other words, one unit drive element 110 faces the first pair of the ground electrode 122a and the drive electrode 124a which are placed and faced in the direction in which the spring portion 116 can bend, and spaced apart in the direction in which the spring portion 116 can bend. And a second pair of a ground electrode 122b and a drive electrode 124b.

As shown in FIG. 4, the first ground electrode 1
22a is a silicon layer 132 and its first drive electrode 1
It has a silicon oxide layer 134 which is an insulating layer covering a surface facing 24a, and a silicon oxide layer 136 which is an insulating layer covering the opposite surface. Also, the first drive electrode 12
4a shows a silicon layer 142 and its first ground electrode 12
Silicon oxide layer 1 which is an insulating layer covering a surface facing 2a
44. The second ground electrode 122b and the second drive electrode 124b have the same structure.

The silicon 132, the silicon oxide layer 134, and the silicon oxide layer 136 form a part of the first electrode support 112, and a part of the spring 116 and a part of the second electrode support 114. Is composed. Silicon layer 1
32 has a thin part, and this part constitutes a part of the spring part 116. Two adjacent unit driving elements 11
The portion sandwiched between the thin portions of the zero silicon layer 132 forms a part of the second electrode support 114.

The silicon layer 142 and the silicon oxide layer 144 form a part of the second electrode support 114. The silicon layer 142 has a convex portion, and the convex portion has the silicon layer 13 with the silicon oxide films 134 and 144 interposed therebetween.
2 are connected. Silicon 132, which is the main material of the first ground electrode 122a, and silicon 142, which is the main material of the first drive electrode 124a, are electrically insulated from each other by the insulating layer 134 and the insulating layer 144 that cover them. ing.

Drive electrodes 1 of two adjacent unit drive elements
24a is electrically connected to the common wiring 148 via the contact hole 146. Similarly, the drive electrodes 124b of two adjacent unit drive elements are electrically connected to a common wiring 148 via a contact hole 146. The wiring 148 extends over the silicon oxide layer 136.

As shown in FIG. 6, the beam support 10
4 has a plurality of power supply pads 152 therein, and each of the power supply pads 152 is connected to a corresponding one of the drive electrodes 124 of two adjacent unit drive elements via a corresponding wiring 148.
a and 124b. Further, the beam supporter 104 includes a pair of power supply pads 154.
(Only one is shown in the figure), and each of the power supply pads 154 is electrically connected to one of the ground electrodes 122a and 122b.

As shown in FIG. 5, the beam support 10
4 is a power supply pad 15 for the drive electrodes 124a and 124b.
2 and a plurality of openings 156 for electrical connection with external devices
have. The plurality of openings 156 are formed on the front side visible in FIG. 5 and on the back side located on the opposite side and not visible in FIG. In addition, a power supply pad 154 for the ground electrodes 122a and 122b and a pair of openings 158 for electrical connection with the outside are provided. The openings 158 are formed one by one on the front side seen in FIG. 5 and on the back side that is located on the opposite side and not seen in FIG.

FIG. 7 is a diagram for explaining the operation of the electrostatic actuator 100 according to the present embodiment. In the above-described electrostatic actuator 100, the ground electrodes 122a and 1
When a voltage is applied to the upper first drive electrode 124a in a state where the second drive electrode 124b and the lower second drive electrode 124b are maintained at the ground potential, the ground electrode 122a is moved upward by electrostatic attraction with the spring portion 116 as a fulcrum. 7, the movable beam 102 warps upward as a whole, as shown in FIG.

On the contrary, the upper first drive electrode 12
4a at the ground potential and the lower second drive electrode 124b
When a voltage is applied to the movable beam 102, the movable beam 102 is entirely warped downward.

Further, as described above, the drive electrodes 124a and 124b of the unit drive elements 110 arranged in series
Are electrically connected to each other, but are electrically separated from each other in units of two. Therefore, the voltage applied to the drive electrodes 124a and 124b can be controlled independently for each two adjacent unit drive elements 110. This makes it possible to displace two adjacent unit driving elements 110 at arbitrary positions on the movable beam 102, so that the total amount of displacement of the movable beam 102 is reduced by the number of drive electrodes 124a and 124b for applying a voltage. By changing, it can be controlled in small increments.

FIGS. 8 to 17 are perspective views showing steps of manufacturing a movable beam of the electrostatic actuator 100 according to the present embodiment. Hereinafter, the movable beam 10 of the electrostatic actuator 100 according to the present embodiment will be described with reference to FIGS.
2 will be described.

First, as shown in FIG. 8, SOI (Silico
n on Insulator) substrate is prepared, and the active layer is formed by RIE (Reactive) using a photoresist (not shown) or the like as a mask.
IonEtching) and ICP (Inductively Coupled Plasm)
a) The drive electrode 202 and the bonding part 204 are formed by selectively removing twice by etching. Here, 206 and 208 are a support layer and a buried oxide film of the SOI substrate, respectively.

Next, another SOI substrate is prepared, and its active layer is selectively removed in the same manner as in FIG. 8, thereby obtaining a ground electrode 212 and an electrode post 214 as shown in FIG.
To form Where 216 and 218 are S
These are the support layer and the buried oxide film of the OI substrate.

Next, as shown in FIG. 10, FIGS.
Thermal oxide films 222, 224 on the surface of the substrate processed in step
Are formed, the bonding portion 204 in FIG.
Positioning is performed so as to be in contact with the electrode post 214 in FIG. 9, and the two substrates are joined.

Next, the supporting layer 216 is formed of TMAH (Tetramethy
After removal with ammonium hydroxide or the like, the buried oxide film 218 is removed by RIE. Further, FIG.
As shown in FIG.
Is partially removed by RIE using as a mask, thereby forming a wiring groove 238.

Next, after removing the photoresist 236,
Thermal oxidation is performed, and a portion of the newly formed thermal oxide film is buffered using a photoresist as a mask.
An oxide film mask (not shown) is formed by removing by IE. Next, through this oxide film mask, the underlying silicon is removed by TMAH,
The recess 242 shown in FIG. 12 is formed. Next, after removing the oxide film mask, thermal oxidation is performed again to form a silicon oxide film 244 shown in FIG. Further, a contact hole 246 is formed by removing a part of the silicon oxide film 244 by RIE through a photoresist. Here, at the same time as the formation of the contact hole 246, the portion of the silicon oxide film indicated by 248 in the figure is removed.

Next, after removing the photoresist, a dopant is added to the contact hole 2 by a method such as ion implantation.
By diffusing into the silicon layer 46 below, a high concentration dopant diffusion layer is formed in this portion.

Further, as shown in FIG. 13, after a conductive film such as aluminum is formed by a method such as a sputtering method, a part of the conductive film is removed through a photoresist or the like to form a wiring 252. I do.

Next, as shown in FIG. 14, by using the silicon oxide film 244 as a mask, silicon is removed by ICP etching to separate the ground electrode 212 and the electrode post 214 from the substrate,
54 are formed. Further, the polyimide film 25 is formed on a large area of the portion where the buried oxide film 208 is exposed.
6 is formed by a method such as a screen printing method.

Next, as shown in FIG. 15, two structures formed in the process of FIG. 14 are aligned so that each structure is mirror-symmetric with respect to the bonding surface, and then the two are bonded. I do. This bonding is performed at a temperature lower than the melting point of the wiring material used in the structure or the thermal decomposition temperature of the polyimide. Further, the support layer 206 shown in FIG.

The removal of the support layer 206 is performed by sealing the space 258 where the actuator is formed with the TMA.
H or the like. When the support layer 206 is completely removed, the liquid pressure of TMAH acts on the buried oxide film 208. Since this portion is reinforced by the polyimide film 256 formed in the step of FIG.
08 is prevented from being damaged by the hydraulic pressure.

Finally, the buried oxide film 208 and the polyimide film 256 are removed by RIE, whereby the movable beam 102 shown in FIGS. 3 and 4 is completed. In order to improve the reliability of the wiring, a silicon oxide film or the like is formed on the surface of the wiring 252 by P-CVD (Plasma Assisted Chemical Vapor).
or Deposition) method.

Since the electrostatic actuator according to the embodiment of the present invention is manufactured by laminating the same two sheets, the wiring 148 is formed on the upper and lower surfaces of the wiring groove as shown in FIG. Therefore, as shown in FIG. 6, the power supply pad 152 is formed on both the upper side and the lower side of the beam support 104.

FIGS. 16 and 17 are perspective views showing the steps of manufacturing the beam support portion corresponding to the steps of FIGS. 13 and 15, respectively.

FIG. 16 shows the structure near the power supply pad at the time when the step shown in FIG. 13 is completed. The support portion 262 is provided with the drive electrode 20 formed in the process of FIG.
2 and the joint 204. In addition, the support portion 264 is connected to the ground electrode 21 formed in the process of FIG.
2 and the electrode posts 214. The opening 266 is formed simultaneously in the step of forming the support 262 and the support 264. Power supply pad 2
68, 272 are wirings 252 formed in the process of FIG.
At the same time, the contact hole 270 is formed as shown in FIG.
Is formed simultaneously with the contact hole 246 formed in the step. The power supply pad 272 is connected to the support 264 via the contact hole 270. A high-concentration dopant diffusion layer (not shown) is formed in a portion of the support portion 264 that is in contact with the power supply pad 272.

Next, as shown in FIG. 17, after a polyimide film 256 is formed on a large area of the portion where the buried oxide film 208 is exposed, the structure formed through the process of FIG. Two pieces are joined. The two structures to be joined are different in the positions of the power supply pads 268 and 272 and the opening 266, and the power supply pad and the opening of one structure face the opening and the power supply pad of the other structure, respectively. Are arranged as follows.

Next, the support layer 206 is removed. In this step, the support layer 206 of the lower structure shown in FIG.
Is removed via the mask 274 to form the holding section 160 shown in FIG. The mask 274 is used by patterning a thermal oxide film formed on the back surface of the substrate during the process. Further, the structure around the pad is completed by removing the buried oxide film 208 and the polyimide film 256.

The electrostatic actuator of this embodiment is
Various modifications and changes are possible.

In the electrostatic actuator of the above-described embodiment, in order to displace the movable beam in both the up and down directions,
Each unit driving element has one pair of a ground electrode and a driving electrode symmetrically on both sides in the direction in which the movable beam extends (in other words, the axis of the beam). In the case where displacement to one side is required, each unit driving element has a pair of ground electrode and driving electrode on one side in the direction in which the movable beam extends (in other words, the axis of the beam). All you have to do is. Specifically, such a structure is obtained by sequentially removing the support layer 206, the buried oxide film 208, and the polyimide film 256 without bonding the same structure after the step shown in FIG. Can be made.

In the electrostatic actuator of the above-described embodiment, the pair of the ground electrode and the drive electrode is a pair of plate-like electrodes facing each other at an interval. For example, the shape may be arbitrarily changed. For example, as shown in FIG. 18, each pair of the drive electrode and the ground electrode has a plurality of teeth, and the teeth of one comb-shaped electrode extend between the teeth of the other comb-shaped electrode. It may be a comb-shaped electrode. Such a comb electrode may be formed, for example, by the steps shown in FIGS.

In the electrostatic actuator of the above-described embodiment, as shown schematically in FIG. 2, the plurality of unit driving elements are alternately arranged in the opposite direction along the direction in which the movable beam extends. However, the arrangement of the unit driving elements is not limited to this, and it is only necessary to arrange them in series. For example, as shown in FIG. 19 and as schematically shown in FIG. 20, the plurality of unit drive elements may be arranged in the same direction along the direction in which the movable beam extends. Such a movable beam can be produced by the same method as that of the present embodiment except that the pattern of etching is changed in the step shown in FIG.

The electrostatic actuator of this embodiment is
Since the movable beam has a plurality of unit driving elements connected in series, it is possible to increase the displacement of the actuator and to secure a sufficient driving force without increasing the distance between the ground electrode and the driving electrode. Is achieved at the same time. Further, since the unit drive elements can be independently controlled for every two adjacent ones, it is possible to finely control the displacement of the actuator (of course, it is also possible to make a change such that the unit drive elements are controlled independently one by one. ). Since this control is performed by changing the number of unit drive elements that apply a voltage to the drive electrodes, without performing D / A conversion,
It can be controlled directly by digital circuits.

[Second Embodiment] A movable beam of an electrostatic actuator according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 21 shows a movable beam of the electrostatic actuator according to the second embodiment.

As shown in FIG. 21, the movable beam 30
2 are three types of unit driving elements 3 connected in series
10, 330, and 350. The first unit drive element 310 can be displaced in the vertical direction, the second unit drive element 330 can be deflected in the left and right direction, and the third unit drive element 350 can be displaced right and left about the axis of the movable beam 302. It can be twisted around.

Here, "the axis of the movable beam 302"
The term shall mean an imaginary line parallel to the direction in which the movable beam 302 extends and passing through the center of the movable beam 302 when the movable beam 302 is not displaced. Also, the term “vertical direction” refers to the movable beam 30.
The term “lateral direction” refers to a direction orthogonal to the two axes, and the term “lateral direction” refers to a direction orthogonal to the axis of the movable beam 302 and orthogonal to the above “vertical direction”.

FIG. 21 shows a plurality of unit drive elements 310, one unit drive element 350 and a plurality of unit drive elements 330.
Are shown, but the number is not limited to this, and may be an arbitrary number of combinations. Further, the movable beam 302 does not necessarily need to include all of the three types of unit drive elements 310, 330, and 350. Depending on the required movement, the first to third unit drive elements 310, 330, Two or one of the 350 may be provided.

As shown in FIGS. 22 and 23, the first unit drive element 310 includes a first electrode support 312, a second electrode support 314, a first electrode support 312, and a second electrode support 312. And a spring part 316 connecting the two electrode support parts 314. The spring part 316 is a flexible spring that can bend vertically in a direction perpendicular to the axis of the movable beam 302.

The first electrode support 312 has two ground electrodes 322a and 322b, and the second electrode support 314 has two drive electrodes 324a and 324b. That is, the first unit driving element 310 includes two pairs of the ground electrode and the driving electrode, that is, the ground electrode 322a.
And a first pair of drive electrodes 324a, and a second pair of ground electrodes 322b and drive electrodes 324b.

The ground electrodes 322a and 322b and the drive electrode 3
24a and 324b are comb-shaped electrodes each having a plurality of teeth, and each pair of comb-shaped electrodes has one tooth interposed between the other teeth, and the teeth of each pair of comb-shaped electrodes are It extends along the direction in which the movable beam 302 extends.

The first pair of comb electrodes (that is, the ground electrode 3
22a and the drive electrode 324a) are positioned off the axis of the movable beam 302 in a direction in which the spring portion 316 can bend. Similarly, the second pair of comb-shaped electrodes (that is, the ground electrode 322b and the drive electrode 324b) are positioned off the axis of the movable beam 302 in a direction in which the spring portion 316 can bend. Further, the first pair of comb electrodes (ie, ground electrode 322a and drive electrode 324a) and the second pair of comb electrodes (ie, ground electrode 322b and drive electrode 324b)
The spring portion 316 is located in plane symmetry with respect to a plane passing through the axis of the movable beam 302 and orthogonal to the direction in which the spring portion 316 can bend.

The operation of the first unit driving element 310 will be described with reference to FIG. FIG. 28 is a side view of a structure in which a plurality of first unit driving elements 310 are connected in series. In FIG. 28, ground electrodes 322a, 3
When a voltage is applied to the upper drive electrode 324a with the 22b and the lower drive electrode 324b kept at the ground potential, the ground electrode 322a and the upper drive electrode 324a are attracted to each other by electrostatic attraction, and the spring portion 316 is pulled. Causes bending deformation. As a result, the structure shown in FIG. 28 (that is, a part of the movable beam) is warped upward.

On the contrary, the ground electrodes 322a, 32
By applying a voltage to the lower drive electrode 324b while keeping the 2b and the upper drive electrode 324a at the ground potential,
The structure shown in FIG. 28 (that is, a part of the movable beam) warps downward.

Further, by controlling the number of unit drive elements 310 for applying a voltage to the drive voltage, the amount of warpage, that is, the amount of displacement of the structure (that is, a part of the movable beam) shown in FIG. 28 is finely controlled. be able to. Further, for an appropriate unit drive element 310, the upper drive electrode 324a
By applying a voltage to the lower drive electrode 324b for the other appropriate unit drive element 310 while applying a voltage to the other unit drive elements 310, the structure shown in FIG. Can be deformed vertically into a complicated shape.

The first unit driving element 310 shown in FIG. 22 and FIG. 23 has two pairs arranged symmetrically off the axis of the movable beam 302 for movement in both the upward and downward directions. However, for applications in which only movement in one of the upward and downward directions is required, the first unit drive element 310 is provided with the axis of the movable beam 302. It is only necessary to have a pair of the ground electrode and the drive electrode that are arranged out of the way.

As shown in FIGS. 24 and 25, the second unit driving element 330 includes a first electrode support portion 332, a second electrode support portion 334, a first electrode support portion 332, and a first electrode support portion 332. And a spring portion 336 connecting the two electrode support portions 334. The spring portion 336 is a flexible spring that can bend in the left-right direction orthogonal to the axis of the movable beam 302.

The first electrode support 332 has four ground electrodes 342a, 342b, 342c and 342d, and the second electrode support 334 has four drive electrodes 344.
a, 344b, 344c, and 344d. That is, the second unit driving element 330 includes four pairs of the ground electrode and the driving electrode, that is, the first pair of the ground electrode 342a and the driving electrode 344a, and the ground electrode 342b and the driving electrode 3
44b, the ground electrode 342c and the drive electrode 34.
4c, a ground electrode 342d and a drive electrode 344.
d of the fourth pair.

The ground electrodes 342a, 342b, 342c,
342d and drive electrodes 344a, 344b, 344c, 3
44d is a comb-shaped electrode having a plurality of teeth, and each pair of the comb-shaped electrodes has one tooth interposed between the other teeth, and the teeth of each pair of the comb-shaped electrodes are both movable beams. It extends along the direction in which 302 extends.

The first pair of comb electrodes (that is, the ground electrode 3
42a and the drive electrode 344a) and the second pair of comb electrodes (that is, the ground electrode 342b and the drive electrode 344b)
The spring portion 336 is positioned off the axis of the movable beam 302 in a direction in which the spring portion 336 can bend. Further, the first pair of comb electrodes and the second pair of comb electrodes are located plane-symmetrically with respect to a plane passing through the axis of the movable beam 302 and parallel to the direction in which the spring portion 336 can bend.

Similarly, a third pair of comb electrodes (ie, ground electrode 342c and drive electrode 344c) and a fourth pair of comb electrodes (ie, ground electrode 342d and drive electrode 344d)
Are located off the axis of the movable beam 302 in a direction in which the spring portion 336 can bend. In addition, the third pair of comb electrodes and the fourth pair of comb electrodes
, And is located plane-symmetrically with respect to a plane parallel to the direction in which the spring portion 336 can bend.

In addition, the two pairs of first and second pairs of comb electrodes and the third and fourth pairs of two pairs of comb electrodes pass through the axis of the movable beam 302, and The part 336 is located plane-symmetrically with respect to a plane orthogonal to the direction in which the part 336 can bend.

The operation of the second unit driving element 330 will be described with reference to FIG. FIG. 29 is a top view of a structure in which a plurality of second unit driving elements 330 are connected in series. In FIG. 29, the ground electrodes 342a, 3
42b, 342c, 342d and the left drive electrode 34
When a voltage is applied to the right driving electrodes 344c and 344d while the ground electrodes 4a and 344b are maintained at the ground potential, the ground electrodes 342c and 342d and the right driving electrodes 344c and 344d are applied.
d are attracted to each other by electrostatic attraction, and the spring portion 33
6 causes bending deformation. As a result, the structure shown in FIG. 29 (that is, a part of the movable beam) warps to the right.

On the contrary, the ground electrodes 342a, 342
2b, 342c, 342d and right drive electrode 344
If a voltage is applied to the left drive electrodes 344a and 344b while maintaining the c and 344d at the ground potential, the structure shown in FIG. 28 (that is, a part of the movable beam) warps to the left.

By controlling the number of unit drive elements 330 for applying a drive voltage, the amount of warpage, ie, the amount of displacement of the structure (ie, a part of the movable beam) shown in FIG. 29 is finely controlled. be able to. Furthermore, for the appropriate unit drive element 330, the left drive electrode 344
a and 344b, and by applying a voltage to the drive electrodes 344c and 344d on the right side of the other appropriate unit drive elements 330, as shown in FIG.
The structure shown in FIG. 9 (that is, a part of the movable beam) can be deformed into a complicated shape in the left-right direction.

The second unit driving element 330 shown in FIGS. 24 and 25 is provided with a first unit driving element 330 symmetrically displaced from the axis of the movable beam 302 for movement in both the left and right directions. And a second pair of ground electrodes and drive electrodes, and a third and fourth pair of ground electrodes and drive electrodes, but only requiring movement in either the left or right direction , The second unit drive element 330 only needs to have two pairs (eg, first and second pairs) of ground electrodes and drive electrodes that are arranged off-axis of the movable beam 302. Good.

As shown in FIGS. 26 and 27, the third unit driving element 350 includes a first electrode support 352, a second electrode support 354, a first electrode support 352, and a second electrode support 352. And a spring portion 356 connecting the two electrode support portions 354. The spring portion 356 is a torsion spring that can be twisted about the axis of the movable beam 302.

The first electrode support 352 has four ground electrodes 362a, 362b, 362c and 362d, and the second electrode support 354 has four drive electrodes 364.
a, 364b, 364c, and 364d. That is, the second unit driving element 350 includes four pairs of the ground electrode and the driving electrode, that is, the first pair of the ground electrode 362a and the driving electrode 364a, and the ground electrode 362b and the driving electrode 3
64b, the ground electrode 362c and the drive electrode 36
4c, a ground electrode 362d and a drive electrode 364.
d of the fourth pair.

The ground electrodes 362a, 362b, 362c,
362d and drive electrodes 364a, 364b, 364c, 3
64d is a comb-shaped electrode having a plurality of teeth, and each pair of the comb-shaped electrodes has one tooth interposed between the other teeth, and the teeth of each pair of the comb-shaped electrodes are both movable beams. It extends along a direction perpendicular to the axis of 302.

The first pair of comb electrodes (that is, the ground electrode 3
62a and the drive electrode 364a) and the fourth pair of comb-shaped electrodes (that is, the ground electrode 362d and the drive electrode 364d) are symmetrically positioned with respect to an axis extending along the direction in which the movable beam 302 extends. Similarly, a second pair of comb-shaped electrodes (ie, ground electrode 362b and drive electrode 364b) and a third pair of comb-shaped electrodes (ie, ground electrode 362c and drive electrode 3)
64c) is symmetrically located with respect to an axis extending along the direction in which the movable beam 302 extends.

The operation of the third unit driving element 350 will be described with reference to FIG. FIG. 30 is a diagram of the third unit drive element 350 as viewed from the axial direction of the movable beam. In FIG. 30, the ground electrodes 362a, 362b, 362
When a voltage is applied to the drive electrodes 364a and 364d in a state where the drive electrodes 362a and 364d and the drive electrodes 364b and 364c are maintained at the ground potential, the ground electrodes 362a and 362d and the drive electrodes 364a and 364d are attracted to each other by electrostatic attraction. The portion 356 (see FIG. 27) undergoes torsional deformation. As a result, the first electrode support 352 twists clockwise with respect to the second electrode support 354. This allows
The structure connected to the first electrode support 352 twists clockwise relative to the structure connected to the second electrode support 354.

On the contrary, the ground electrodes 362a and 362a
2b, 362c, 362d and drive electrodes 364a, 3
64d at the ground potential, the drive electrode 364b,
If a voltage is applied to the first electrode support portion 352
Are twisted counterclockwise with respect to the second electrode support 354.

The third unit driving element 350 shown in FIGS. 26 and 27 is a first unit driving element 350 which is arranged symmetrically with respect to the axis of the movable beam 302 for rotation in both counterclockwise and clockwise directions. And a fourth pair of ground electrodes and drive electrodes, and a second and third pair of ground electrodes and drive electrodes, but only rotation in one of the left or right direction is required. , The third unit drive element 350 even has two pairs (eg, first and fourth pairs) of ground and drive electrodes arranged symmetrically about the axis of the movable beam 302. I just need.

The first to third unit driving elements 310, 3
30, 350 first electrode supports 312, 332, 35
2 is a first to third unit driving element 3
10, 330, 350 second electrode support portions 314, 33
4, 354. In this manner, a structure in which a plurality of unit driving elements are connected in series (that is, the movable beam 302) is manufactured from a silicon substrate by applying a semiconductor manufacturing process, as described later.

In each of the first to third unit drive elements shown in FIGS. 22 to 27, the first electrode support, the second electrode support, the spring, the ground electrode and the drive electrode are mainly It is made of silicon. The drive electrode is electrically insulated from the second electrode support by the silicon oxide film. The ground electrode is also electrically insulated from the first electrode support by the silicon oxide film.

Each unit driving element 310, 330, 350
As shown in FIGS. 22 to 27, a wiring groove 31 passing through the inside of the first electrode support, the second electrode support, and the spring is provided.
8, 338, and 358. Wiring grooves 318, 33
8 and 358 are electrically insulated from the first electrode support, the second electrode support, and the spring by the silicon oxide film.

Each unit driving element is shown in FIGS.
Although not shown in the figure, a CMOS circuit formed inside the first electrode support and the second electrode support is provided. The drive electrodes are CM
It is electrically connected to the OS circuit. Further, the CMOS circuits inside the adjacent unit drive elements are electrically connected to each other via a wiring extending in the wiring groove. The ground electrodes of adjacent unit driving elements are electrically connected to each other via a wiring extending in the wiring groove.

Further, although not shown, the electrostatic actuator according to the present embodiment has a beam support for supporting the movable beam 302 in a cantilever manner as in the first embodiment. Has a power supply pad, and the power supply pad is electrically connected to a CMOS circuit of an adjacent unit drive element by a wiring extending in the wiring groove.

A CMOS circuit provided inside each of the unit driving elements 310, 330, 350 is used for selecting a driving electrode to which a voltage is applied. As shown in FIG.
The MOS circuit 402 has a shift register 404, a latch circuit 406, and a MOS transistor 408.
The DC power supply 412 and the drive electrode 444 of the unit drive element are connected to the source and the drain of the MOS transistor 408, respectively.

The gate of the MOS transistor 408 is connected to a latch circuit 406 corresponding to the MOS transistor. In the CMOS circuit 402, the latch circuit 406 is connected to a node 418 in the shift register 404, and each node in the shift register 404 has a one-to-one correspondence with each drive electrode 444.

The operation of the CMOS circuit 402 will be described below.

First, an input pulse is input from the terminal 414. The input pulse is sequentially transferred from the input terminal side by the shift register 404. When the input pulse transferred in the shift register 404 reaches the node 418 in the shift register corresponding to the electrode to be driven, the latch circuit controller 410 is operated, and the potential of the node 418 in the shift register is stored in each latch circuit 406. Latch information. By the latched potential information, MO
By controlling the S transistor, the voltage of the power supply 412 is applied to an arbitrary drive electrode 444.

In the embodiment of the present invention, as suggested from FIGS. 25 and 27, in the second unit driving element 330 and the third unit driving element 350, the spring portions 336 and 356 are provided, respectively. It is expected that the width of the wiring groove 338 and the width of the wiring groove 358 formed inside the device cannot be sufficiently secured. However, by providing the CMOS circuit 402 in each unit driving element, the wiring passing through the wiring groove is driven. Regardless of the number of electrodes, 422, 424,
In addition to the wiring indicated by reference numeral 426, only wiring connected to the ground electrode 442 and wiring for supplying a voltage and a driving pulse to each circuit are sufficient, so that a problem caused by a narrow wiring groove does not occur.

Since the drive electrodes of each unit drive element are electrically separated from each other, a voltage can be independently applied to each unit drive element. Therefore, the movable beam 30
2 can be displaced, and the displacement of the entire movable beam can be controlled by the number of unit drive elements to which a voltage is applied.

FIGS. 32 to 41 are perspective views showing the steps of manufacturing the movable beam 302 of the electrostatic actuator according to the present embodiment. Hereinafter, the movable beam 302 of the electrostatic actuator according to the present embodiment will be described with reference to FIGS.
A method of manufacturing the device will be described. 32 to 41 illustrate a portion of the movable beam 302 that includes one first unit driving element 310, one second unit driving element 330, and one third unit driving element 350.

First, as shown in FIG. 32, an SOI substrate having an active layer, a support layer 504, and a buried oxide film 506 is prepared, and the active layer is etched by RIE or ICP using a photoresist (not shown) or the like as a mask. And the ground electrodes 508a and 508 are selectively removed twice.
b, 508c and drive electrodes 510a, 510b, 510
and c. Ground electrodes 508a, 508b, 508
c each have a projecting joint portion 512,
Each of 10a, 510b, and 510c has a projecting joint 514.

The ground electrode 508a and the drive electrode 510a are
The ground electrode and the drive electrode of the first unit drive element 310 respectively become the ground electrode and the drive electrode 510b.
The ground electrode and the drive electrode of the second unit drive element 330 respectively become the ground electrode and the drive electrode 510c.
These become the ground electrode and the drive electrode of the third unit drive element 350, respectively.

Next, the active layer 522 and the support layer 524 are similarly formed.
Another SOI substrate having a buried oxide film 526 and an active layer 522 is prepared, and the active layer 522 is selectively removed by a method similar to the process of FIG. , 528b, 528c, 528
d, and a spring forming portion 530 extending between the electrode support portion 528b and the electrode support portion 528c.

The electrode supporting portion 528a becomes a part of the first electrode supporting portion of the first unit driving element 310, and the electrode supporting portion 528b is connected to the second electrode supporting portion of the first unit driving element 310 and the second electrode supporting portion 528b. It becomes a part of the first electrode support portion of the second unit drive element 330, and the electrode support portion 528c is connected to the second electrode support portion of the second unit drive element 330 and the third unit drive element 35.
The first electrode support portion 528 becomes a part of the first electrode support portion 528.
d becomes a part of the second electrode support of the third unit drive element 350.

The spring formation scheduled portion 530 is for the second unit drive element 330, and finally, the second unit drive element 3
It becomes a part of the spring section 30. Further, the etching of the active layer 522 is stopped before the buried oxide film 526 is exposed, and therefore, the electrode support portions 528a and 528 are stopped.
28b and between the electrode support 528c and the electrode support 52
Between 8d, a thin active layer 522 remains. The thin active layer 522 remaining between the electrode support portion 528a and the electrode support portion 528b becomes a portion where a spring for the first unit drive element 310 is to be formed, and finally becomes one of the spring portions of the first unit drive element 310. Department. Further, the central portion of the thin active layer 522 remaining between the electrode support portion 528c and the electrode support portion 528d becomes a portion where a spring for the third unit drive element 350 is to be formed, and finally, the third unit drive element 350 And a part of the spring part.

The active layer of the SOI substrate used in the steps of FIGS. 32 and 33 has an initial oxygen concentration of 10 to 28.
Use those in the range of ppma (OLD ASTM). In this embodiment, since a MOS transistor is formed inside the element (described later), many heat steps are required. However, depending on the conditions of the heat step, interstitial oxygen contained in silicon is precipitated. In addition, the interstitial oxygen concentration decreases.

When the interstitial oxygen concentration is 10 ppma (OLD AST
It is known that the mechanical strength of silicon decreases sharply when it falls below M) (Takao Abe, Silicon Crystals and Doping (Maruzen Co., Ltd.) P32). By controlling the concentration in the range of 10 to 28 ppma (OLD ASTM), oxygen precipitation due to the thermal process is prevented, and the mechanical strength of silicon constituting the actuator is secured (F. Shimura, Semiconductor Silicon Cr
ystal Technology (Academic Press Inc.), P320).

Next, after forming a thermal oxide film 532 on the surface of the active layer 522 of the structure manufactured by the process of FIG. 33, as shown in FIG. 34, this was manufactured by the process of FIG. Join with the structure.

As shown in FIG. 35, which is a partially cutaway view of the structure of FIG. 34, these two structures are different from each other in that the spring forming portion 534 for the first unit drive element 310 is A spring forming portion 530 for the second unit driving element 330 is provided at the center between the driving electrode 508a and the driving electrode 510a, and a spring forming portion for the third unit driving element 350 is provided at the center between the ground electrode 508b and the driving electrode 510b. 536 is aligned so that it is centered between its ground electrode 508c and drive electrode 510c.

Next, after removing the support layer 524 by TMAH or the like, the buried oxide film 526 is removed by RIE. Further, as shown in FIG.
The wiring groove 544 is formed by partially removing the silicon of the active layer 522 by RIE using 2 as a mask.

Next, after removing the photoresist 542,
Thermal oxidation is performed, and a part of the newly formed thermal oxide film is removed by buffered hydrofluoric acid or RIE using a photoresist as a mask, thereby forming an oxide film mask 546 shown in FIG. Further, as shown in FIG. 37, lower silicon 5 is formed through oxide film mask 546.
The removal of the recesses 54 by TMAH
8 is formed.

Next, after removing the oxide film mask 546, thermal oxidation is performed again, and the silicon oxide film 5 shown in FIG.
Form 50. Further, by removing a part of the silicon oxide film 550 by RIE using a photoresist as a mask, a CMOS formation region 552 shown in FIG.
To expose the silicon.

Subsequently, well formation, gate oxidation, field oxidation, source / drain formation, and the like are sequentially performed to form a CMO.
A MOS transistor is formed in the S formation region 552. Next, a contact hole (not shown) is formed at each terminal of the MOS transistor formed in the CMOS formation region and at the bottom of the concave portion 548, and then shown in FIG. 38 by the same method as in the first embodiment. Wiring 554 and an interlayer insulating film (not shown) are formed.

Next, after partially removing the interlayer insulating film and the silicon oxide film 550 formed in the previous step, the underlying silicon is removed by ICP etching using these as a mask, as shown in FIG. Electrode support 5
28a, 528b, 528c, 528d and spring part 5
Unnecessary portions of the silicon 522 and the silicon oxide film 532 are removed along the contours of 58a, 558b, and 558c. The spring portions 558a, 558b, 558c become part of the spring portions of the first to third unit drive elements 310, 330, 350, respectively.

Further, a polyimide film 560 is formed by a method such as a screen printing method in a portion having a large area in a portion where the buried oxide film 506 is exposed.

Next, as shown in FIG. 40, two structures 562 formed in the step of FIG. 39 are aligned so that each structure is mirror-symmetric with respect to the joint surface, and then both are aligned. Join. This joining is performed at a temperature lower than the melting point of the wiring material used in the structure or the thermal decomposition temperature of the polyimide. Further, the support layer 504 is removed. The removal of the support layer 504 is performed using TMAH or the like in a state where the space 564 in which the actuator is formed is sealed.

The polyimide film 560 functions as a reinforcing material for the buried oxide film 506 as in the first embodiment. Finally, the buried oxide film 506 and the polyimide film 56
0 is removed by RIE, as shown in FIG. 41, the first to third unit driving elements 310, 3
A part of the movable beam 302 including one by one 30 and 350 is completed.

In the case where the surface roughness of the wiring groove 544 adversely affects the characteristics of a CMOS circuit to be formed in a later step, in the step of FIG.
SOI with three layers of silicon and two layers of buried oxide
By using the substrate, one of the buried oxide films may be used as a stop layer for silicon etching when forming an electrode groove.

The beam support of the second embodiment has substantially the same structure as the beam support of the first embodiment, and is not shown in the drawings. As can be understood from the above description of the manufacturing method, since the wiring is formed on the upper surface and the lower surface of the inner surface of the wiring groove, the beam support portion is formed inside the same as in the first embodiment. Openings for electrical connection to the power supply pad are formed on the upper and lower surfaces.

Since the electrostatic actuator according to the present embodiment has a plurality of unit drive elements to which the movable beam is connected in series, the movable beam can be largely displaced by a sufficient driving force. Further, since the unit driving elements can be controlled independently one by one, an arbitrary portion of the movable beam can be deformed. By changing the number of unit drive elements to be driven, the entire displacement of the movable beam can be directly controlled by a digital circuit without performing D / A conversion.

Further, since the movable beam includes a plurality of types of unit driving elements, the electrostatic actuator according to the present embodiment can perform a plurality of types of displacement, for example, warping or twisting in the vertical and horizontal directions. Can occur. Therefore, it can be applied to various uses such as an arm and a walking mechanism of a micro factory and a micro robot, a catheter, an optical switch, and the like.

[Mirror Array] Next, a mirror array which is another aspect of the present invention will be described. In the following description, first, the background of the mirror array will be described, and then, specific embodiments of the mirror array will be described.

Japanese Patent Application Laid-Open No. 6-207853 discloses a compact spectroscopic device using a mirror array driven by electrostatic force. As shown in FIG. 53, the spectroscopic device includes a slit 1102, a collimator 1104, a prism 1106, a spatial light modulator 1108, a light collecting mirror 1110, and a detector 1112.

In FIG. 53, light transmitted through a slit 1102 is converted into a parallel light beam by a collimator 1104, is split by a prism 1106, and then enters a spatial light modulator 1108. Here, prism 1106
The light separated by is directed at a unique angle for each wavelength of the light included in the incident light, so that light components having different wavelengths are incident on different positions on the spatial light modulator 1108. Therefore, only light having a specific wavelength is detected from the light having entered the pinhole 1102 by the detector 1112 by outputting only the light incident on a specific position to the condenser mirror 1110 by the spatial light modulator 1108. can do.

As the spatial light modulator 1108, there are a mirror array, a shutter array, a filter array, and the like. Among them, the mirror array has a small loss and can output a plurality of lights incident on different positions simultaneously in different directions. Has advantages. As one of spatial light modulators using this mirror array, a DMD (Digital Micromirror) is used.
Ror Device) is disclosed in JP-A-2000-28937.

As shown in FIG. 54, the DMD has a drive electrode 1202, a ground electrode 1204, a torsion bar post 1206, a torsion bar 1208, a mirror post 1210, and a mirror 1212.

The ground electrode 1204 is deflectably supported by a pair of torsion bars 1208 made of a conductive elastic material. The torsion bar 1208 is supported by a pair of conductive torsion bar posts 1206, and the ground electrode 1204 is connected to the torsion bar 120.
8 and the torsion bar post 1206 are maintained at the set potential. The mirror post 1 is connected to the ground electrode 1204.
210 is attached, and the mirror 1212 is fixed to the mirror post 1210. Drive electrode 1202
Are arranged symmetrically with respect to the deflection axis of the ground electrode 1204, one by one, facing the ground electrode 1204.

In the DMD, as shown in FIG. 55, with the ground electrode 1204 and one drive electrode 1202a grounded, the power supply 1220 is connected to the other drive electrode 1202b.
When a voltage is applied to the surface of the ground electrode 1204 and the drive electrode 1202b, charges 1224, 1
222 is induced, and one side of the ground electrode 1204 is attracted in the direction of the drive electrode 1202b by the electrostatic force acting between the charge 1224 and the charge 1222. Therefore, the mirror 1212 fixed to the ground electrode 1204 is deflected via the mirror post 1210, and the direction of the light reflected by the mirror 1212 changes.

The mirrors 1212 are two-dimensionally arranged as shown in FIG. 54. By deflecting a specific mirror 1212 in the direction of the condensing mirror 1110 in FIG. Can selectively detect only light of a specific wavelength.

The light beam transmitted through the spectroscope 1106 in FIG. 53 is projected on the surface of the spatial light modulator 1108 to an oval region 1236 having a major axis 1232 and a minor axis 1234 as shown in FIG. Here, the area 1236
Of the light projected on the region 123
6 are separated in the major axis direction, so that the major axis direction is X in FIG.
If you place prisms and spatial light modulators so that they align in the direction,
The position of the mirror in the X direction corresponds to the wavelength of light output from the spatial light modulator.

In FIG. 53, the light output from the spatial light modulator 1108 in the direction of the condensing mirror 1110 includes, in addition to the light of the desired wavelength, the adjacent mirror 1 in FIG.
The scattered light from the end surface 1242 of 212 is included as stray light, and this scattered light deteriorates the S / N ratio of the detection signal.

This inconvenience is reduced by arranging strip-shaped mirrors long in one direction in a straight line as shown in FIG. That is, as shown in FIG. 57, by changing the mirror of the spatial light modulator to a mirror 1252 having one side longer than the minor axis of the region 1236, the scattered light from the end face of the adjacent mirror is y. End face 125 warped in the direction
6 and only the scattered light from end face 125 along the X direction
Since the scattered light from 4 is lost, stray light is reduced.

In such a spatial light modulator, FIG.
When the mirror 1252 is deflected about the Y direction 7 as an axis, a part of the reflected light from the mirror 1252 is blocked by the adjacent mirror, so that the signal intensity is reduced. Therefore, it is desirable that the mirror 1252 be deflected around the X direction in FIG.

A driving mechanism for this purpose, that is, a DMD includes a mirror 1252 and a driving electrode 1262 as shown in FIG.
And the ground electrode 1264 have a relatively long dimension in a direction orthogonal to the mirror deflection axis. Mirror 1252
It cannot be deflected to an angle larger than the angle at which the end surface of the ground electrode 1264 and the drive electrode 1262 contact. For this reason, FIG.
The drive mechanism of No. 8 has a smaller deflection angle if the distance between the drive electrode and the ground electrode is the same as compared with the drive mechanism of FIG. For this reason, in the spectrometer of FIG.
The distance between the spatial light modulator 1108 and the condenser mirror 1110 or detector 1112 must be increased, which leads to an undesirable increase in the size of the optical system.

In order to obtain a large deflection angle of the mirror 1252 in the driving mechanism shown in FIG.
The distance between the driving electrode 1262 and the ground electrode 1264 can be reduced because the electrostatic attraction acting between the two electrodes decreases in proportion to the square of the electrode distance.
When the distance between the mirrors 125 is increased, it becomes impossible to secure a sufficient driving force of the mirror 1252.

Since the electrostatic force acting between the electrodes is proportional to the square of the applied voltage, the driving electrode 1262 and the ground electrode 1264
By increasing the voltage applied between the electrodes, it is possible to compensate for the decrease in the electrostatic attraction due to the increase in the electrode spacing described above. However, the voltage includes the electrostatic withstand voltage between each electrode or between the wires connected to the electrodes. , The applied voltage cannot be increased without limit.

Further, when it is desired to simultaneously detect a plurality of lights having different wavelengths as in a scanning microscope disclosed in JP-A-6-207853, as shown in FIG. 59, the spatial light modulator 1302 It is necessary to direct the light flux to any one of the plurality of detectors 1304, 1306, and 1308 arranged in different directions with respect to. However, in the DMD, the electrostatic attraction acting between the drive electrode and the ground electrode does not change linearly with the applied voltage, and the electrostatic attraction depends not only on the applied voltage but also on the electrode spacing. It is extremely difficult to accurately control the angle to any one of a plurality of different constant values.

The mirror array of the present invention overcomes such technical difficulties by utilizing the above-described electrostatic actuator of the present invention. The mirror angle can be set to one of a plurality of different constant values. One can control precisely. Hereinafter, an embodiment of a mirror array which is another aspect of the present invention will be described.

[Third Embodiment] A mirror array according to a third embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 42, the mirror array of the present embodiment has a plurality of movable beams 602 and a beam support 604 for supporting the plurality of movable beams 602 in a cantilever manner.
And a plurality of mirrors 606 provided at each free end of the movable beam 602. The mirror 606 has an elongated strip shape along the axis of the movable beam 602.

As shown in FIG. 43, each of the movable beams 602 includes a plurality of unit driving elements 6 connected in series.
It has ten. Each of the unit driving elements 610 includes a first electrode support 612, a second electrode support 614, and a spring 616 connecting the pair of electrode supports 612, 614. The plurality of unit driving elements 610 include
Along the axis of the movable beam 602, they are alternately arranged in opposite directions. The spring 616 is a flexible spring that can bend in a direction perpendicular to the axis of the movable beam 602.

The first electrode support 612 includes two ground electrodes 622a and 622b, and the second electrode support 614 includes two drive electrodes 624a and 624b.
Contains. That is, one unit driving element 610
Are a pair of a ground electrode 622a and a drive electrode 624a facing each other in the direction in which the spring portion 616 can bend, and a ground electrode 622b and a drive electrode facing each other in the direction in which the spring portion 616 can bend. 624b has a second pair.

The unit driving element 610 is substantially the same as the unit driving element 110 of the first embodiment.

The movable beam 602 has a wiring groove 632 extending inside along the axis thereof.
Ten drive electrodes 624a, 624b and ground electrode 62
2a and 622b are electrically connected to a wiring 634 extending in the wiring groove 632 via a contact hole.

The beam support 604 has one CMOS circuit 640 for one movable beam 602 therein.
have. The CMOS circuit 640 is electrically connected to driving electrodes 624a and 624b through a wiring 634. The CMOS circuit 640 is electrically connected to an adjacent CMOS circuit via a wiring 644 extending in a wiring groove 642 formed in the beam support 604.

The CMOS circuit 640 includes the movable beam 602
Drive electrodes 624a, 62 of any unit drive element 610
This is a circuit for selectively applying a voltage to 4b, which is the same as the CMOS circuit described with reference to FIG. 31 in the second embodiment.

The mirror array 6 according to the present embodiment as described above.
At 00, as can be easily understood from the description of the first embodiment, the movable beam 602 warps in the vertical direction according to the application of the voltage to the drive electrodes 624a and 624b of the unit drive element 610, and as a result, The angle of the mirror 606 provided at the free end of the movable beam 602 changes. Further, the amount of displacement of the movable beam 602, that is, the angular displacement of the mirror 606 can be finely controlled by changing the number and position of the unit drive elements 610 to which a voltage is applied.

The mirror array 600 of the present embodiment is manufactured from a silicon substrate by applying a semiconductor manufacturing process. The manufacturing method is similar to the method of manufacturing the electrostatic actuator according to the first embodiment.
This will be briefly described with reference to FIG. 44 to 49 illustrate one unit drive element and a mirror at the tip of the movable beam 602.

First, as shown in FIG. 44, an SOI substrate having an active layer, a support layer 704 and a buried oxide film 706 is prepared, and the active layer is etched by RIE or ICP using a photoresist (not shown) or the like as a mask. By selectively removing the electrode twice, a drive electrode 712 and a joint 714 protruding therefrom are formed.

A plurality of drive electrodes 712 and bonding portions 714 are formed along the direction in which the movable beam to be formed extends, and a plurality of drive electrodes 712 corresponding to one movable beam are formed.
A plurality of sets of the joints 714 are formed adjacent to each other so as to correspond to a plurality of movable beams extending adjacent to each other.

Next, the active layer 722 and the support layer 724 are similarly formed.
44, another SOI substrate having a buried oxide film 726 is prepared, and the active layer 722 is selectively removed by a method similar to that of the step of FIG. Electrode post 734 and movable plate 736
To form The etching of the active layer 722 is stopped before the buried oxide film 726 is exposed, leaving a thin active layer 722 remaining between the ground electrode 732 and the electrode post 734.

A plurality of ground electrodes 732 and electrode posts 734 are formed along the direction in which the movable beam to be formed extends.
Further, a plurality of drive electrodes 7 corresponding to one movable beam
A pair of the joint 12 and the joint portion 714 and the movable plate 736 are formed adjacent to each other in a plurality corresponding to a plurality of movable beams extending adjacent to each other.

S used in the steps of FIGS. 44 and 45
The active layer of the OI substrate has an initial oxygen concentration of 10 to 28 pp.
It is good to use the one in the range of ma (OLD ASTM). This is, as explained in connection with the second embodiment,
This is because the reduction of the interstitial oxygen concentration due to the heat treatment at the time of forming the S transistor is suppressed and the mechanical strength of silicon is ensured.

Next, a thermal oxide film 742 is formed on the surface of the structure manufactured in the step of FIG. 44, and a thermal oxide film 744 is similarly formed on the surface of the structure manufactured in the step of FIG. As shown in FIG. 46, the joint 714 and the electrode post 7
34 are brought into contact to join them together.

Next, after removing the support layer 724 by TMAH or the like, the buried oxide film 726 is removed by RIE. In addition, silicon is selectively etched,
As shown in FIG. 47, after a wiring groove 752 and a concave portion 754 are formed, a silicon oxide film 756 is formed, and portions corresponding to movable beams to be formed are selectively removed.

Next, well formation, gate oxidation, field oxidation, source / drain formation, and the like are sequentially performed in a region where a support portion is to be formed, thereby forming a CMOS circuit. Next, CM
A contact hole is formed at each terminal of the OS circuit and at the bottom of the concave portion 754. Further, after forming a conductive film of aluminum or the like by a sputtering method or the like, by removing a part of the conductive film via a photoresist or the like,
As shown in FIG. 48, the wiring 7 connected to the drive electrode
62 and a wiring connected to the CMOS circuit (not shown)
To form Further, an interlayer insulating film is formed as necessary.

Further, using the silicon oxide film 756 as a mask, the exposed silicon is removed by the ICP etching method, so that the adjacent ground electrode 732, electrode post 734, and movable plate 736 are separated from each other.

Two structures formed in the step of FIG. 48 are prepared, and these two structures are positioned so that the surfaces of the silicon oxide film 756 face each other and are mirror-symmetric with respect to the bonding surface. Join and join together. This joining is performed at a temperature lower than the melting point of the wiring member used for the structure. Further, the support layer 704 and the buried oxide film 7
06 is removed. This results in a plurality of movable beams 602 extending adjacent to each other, as shown in FIG.
Is obtained.

Regarding the step of removing the support layer 704, the silicon oxide film formed in the previous step is partially left on one of the support layers 704, and the support layer 704 is etched using the silicon oxide film as a mask. The actuator support 764 shown in FIG. 43 is formed at the same time.

Finally, a metal film is selectively formed on the surface of the movable plate 736 to form a reflection surface 764. The result is a structure or mirror array having a plurality of adjacently extending movable beams 602, each of which has a mirror 606 extending continuously from its free end, as shown in FIG.

In the case where the surface roughness of the wiring groove 752 adversely affects the characteristics of a CMOS circuit to be formed in a later step, the step shown in FIG.
SOI with three layers of silicon and two layers of buried oxide
By using the substrate, one of the buried oxide films may be used as a stop layer for silicon etching when forming an electrode groove.

[Fourth Embodiment] A mirror array according to a fourth embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 50, the mirror array 800 of the present embodiment has a plurality of movable beams 802, a beam support 804 for supporting the plurality of movable beams 802 in a cantilever manner, and each of the movable beams 802. And a plurality of mirrors 806 provided at the free end of the mirror. Mirror 806
Has a strip shape elongated along the axis of the movable beam 802.

As shown in FIG. 51, each of the movable beams 802 includes a plurality of unit driving elements 8 connected in series.
It has ten. Each of the unit driving elements 810 includes a first electrode support 812, a second electrode support 814, and a spring 816 connecting the pair of electrode supports 812 and 814. The plurality of unit driving elements 810 include:
They are aligned in the same direction along the axis of the movable beam 802. The spring 816 is a flexible spring that can bend in a direction perpendicular to the axis of the movable beam 802.

The first electrode support 812 includes two ground electrodes 822a and 822b, and the second electrode support 814 includes two drive electrodes 824a and 824b. That is, the unit driving element 810 has two pairs of the ground electrode and the drive electrode, that is, the first pair of the ground electrode 822a and the drive electrode 824a, and the second pair of the ground electrode 822b and the drive electrode 824b. are doing.

The ground electrodes 822a and 822b and the drive electrode 8
24a and 824b are comb-shaped electrodes each having a plurality of teeth, and each pair of comb-shaped electrodes has one tooth interposed between the other teeth, and the teeth of each pair of comb-shaped electrodes are It extends along the axis of the movable beam 802.

This unit drive element 810 is substantially the same as the first unit drive element 310 of the second embodiment.

As shown in FIG. 52, the movable beam 80
2 has a wiring groove 832 extending inside along its axis. In other words, each of the unit driving elements 810 includes
A wiring groove 832 extending through the inside of the first electrode support portion 812, the second electrode support portion 814, and the spring portion 816 is provided. Inside the wiring groove 832 of each unit drive element 810,
As in the second embodiment, a CMOS circuit is formed. Alternatively, the CMOS circuit may be provided inside the beam support 804 as in the third embodiment. The terminals of the CMOS circuit are connected to drive electrodes 822a and 822 through contact holes by wiring (not shown).
b and is electrically connected.

On the upper and lower surfaces of the wiring groove 832, a wiring 834 extending along the axis of the movable beam 802 is formed, and the CMOS circuit of each unit drive element 810 and the electrical connection between the ground electrodes 822a and 822b are formed. Connection has been established. Further, the wiring 834 is similar to the third embodiment,
It extends to a wiring groove formed inside the support portion 804, and extends inside the wiring groove for electrical connection with an external circuit, or electrically connects with another movable beam wiring through the wiring groove. Connected.

The CMOS circuit is a circuit for selectively applying a voltage to the drive electrodes 824a and 824b of an arbitrary unit drive element 810 of the movable beam 802, which is shown in FIG. 31 in the second embodiment. CMO explained
It is the same as the S circuit.

The mirror array 8 according to the present embodiment as described above.
In 00, as can be easily understood from the description of the first embodiment, the movable beam 802 warps in the vertical direction according to the application of the voltage to the drive electrodes 824a and 824b of the unit drive element 810, and as a result, The angle of the mirror 806 provided at the free end of the movable beam 802 changes. Further, the amount of displacement of the movable beam 802, that is, the angular displacement of the mirror 806 can be finely controlled by changing the number and position of the unit drive elements 810 to which a voltage is applied.

The mirror array 800 of the present embodiment is manufactured from a silicon substrate using a semiconductor manufacturing process, as in the third embodiment. As can be easily analogized from the description of the second embodiment and the third embodiment, each of the plurality of movable beams forming the first unit driving element 310 described in detail in the second embodiment is formed. In addition, as described in the third embodiment, it can be manufactured by forming a movable plate together at the distal end thereof, as described in the third embodiment.

Although some embodiments have been described in detail with reference to the drawings, the present invention is not limited to the above-described embodiments, and may be carried out without departing from the scope of the invention. Including all implementations.

Accordingly, the present invention includes the electrostatic actuators or mirror arrays described in the following sections.

1. An electrostatic actuator driven by electrostatic force, the movable actuator having a movable beam and a beam support unit for supporting the movable beam in a cantilever manner, and the movable beam includes a plurality of unit driving elements connected in series. The unit drive element has a pair of electrode support portions, a spring portion connecting the pair of electrode support portions, and at least a pair of electrode elements provided on each of the electrode support portions. , Electrostatic actuator.

[0171] 2. 2. The electrostatic actuator according to claim 1, wherein the unit driving element has two pairs of electrode elements provided on each of the electrode support portions.

[0172] 3. 3. The electrostatic actuator according to claim 1, wherein the plurality of unit drive elements are alternately arranged in a reverse direction along a direction in which the movable beam extends.

4. 3. The electrostatic actuator according to claim 1, wherein the plurality of unit drive elements are arranged in the same direction along the direction in which the movable beam extends.

[0174] 5. The pair of electrode elements is a pair of plate electrodes, and the pair of plate electrodes face each other at an interval.
Item 3. The electrostatic actuator according to item 1 or 2.

6. Item 1. The pair of electrode elements is a pair of comb electrodes, each of the pair of comb electrodes has a plurality of teeth, and the teeth of one comb electrode extend between the teeth of the other comb electrode. Or the electrostatic actuator according to item 2.

7. The movable beam has at least one first unit drive element, and the first unit drive element is a flexible spring whose spring portion can bend in a direction orthogonal to the direction in which the movable beam extends. 1st or 2nd
An electrostatic actuator according to the item.

8. The movable beam further has at least one second unit drive element, and the second unit drive element is a flexible spring whose spring portion can flex in a direction orthogonal to the direction in which the movable beam extends, 3. The electrostatic actuator according to claim 1, wherein the direction in which the spring portion of the second unit drive element bends is orthogonal to the direction in which the spring portion of the first unit drive element bends.

9. The movable beam further has at least one third unit drive element, the third unit drive element having a torsion spring whose spring portion can be twisted about an axis extending along the direction in which the movable beam extends. Item 3. The electrostatic actuator according to Item 1 or 2, wherein

10. The movable beam is the electrostatic actuator according to the first or second item having at least one type of unit driving element selected from the first to third unit driving elements, wherein Is a bending spring whose spring portion can bend in a direction orthogonal to the direction in which the movable beam extends, and the second unit drive element has a spring portion in a direction in which the spring portion is orthogonal to the direction in which the movable beam extends. The direction in which the spring portion of the second unit drive element bends is orthogonal to the direction in which the spring portion of the first unit drive element bends, and the third unit drive element is a spring that can bend. The part is a torsion spring that can be twisted about an axis extending along the direction of extension of the movable beam.

11. The movable beam is the electrostatic actuator according to the first or second item having at least two types of unit driving elements selected from the first to third unit driving elements, wherein Is a bending spring whose spring portion can bend in a direction orthogonal to the direction in which the movable beam extends, and the second unit drive element has a spring portion in a direction in which the spring portion is orthogonal to the direction in which the movable beam extends. The direction in which the spring portion of the second unit drive element bends is orthogonal to the direction in which the spring portion of the first unit drive element bends, and the third unit drive element is a spring that can bend. The part is a torsion spring that can be twisted about an axis extending along the direction in which the movable beam extends.

12. The movable beam is the electrostatic actuator according to the first or second item having three types of unit driving elements selected from the first to third unit driving elements, wherein The unit drive element is a flexible spring whose spring portion can bend in a direction perpendicular to the direction in which the movable beam extends, and the second unit drive element has a spring portion in the direction orthogonal to the direction in which the movable beam extends. The direction in which the spring portion of the second unit drive element bends is orthogonal to the direction in which the spring portion of the first unit drive element bends, and the third unit drive element has its spring portion. Is a torsion spring that can be twisted about an axis extending along the direction in which the movable beam extends.

13. The first unit driving element has at least a pair of comb-shaped electrodes, each of the pair of comb-shaped electrodes has a plurality of teeth, and the teeth of one comb-shaped electrode are interposed between the teeth of the other comb-shaped electrode. The teeth of the pair of comb-shaped electrodes extend along the direction in which the movable beam extends, and the pair of comb-shaped electrodes are positioned off the axis extending along the direction in which the movable beam extends, in the direction in which the spring portion bends. Item 13. The electrostatic actuator according to any one of Items 7 to 12.

14. The first unit driving element has two pairs of comb-shaped electrodes, and the two pairs of comb-shaped electrodes pass through an axis extending along the direction in which the movable beam extends and are perpendicular to a plane orthogonal to the direction in which the spring portion bends. , Located in plane symmetry, the seventh
Item 13. The electrostatic actuator according to any one of items 12 to 12.

15. The second unit driving element has at least two pairs of comb-shaped electrodes, each pair of comb-shaped electrodes has a plurality of teeth, and the teeth of one comb-shaped electrode are interposed between the teeth of the other comb-shaped electrode. The teeth of each pair of comb-shaped electrodes extend along the direction in which the movable beam extends, and each pair of comb-shaped electrodes is displaced from the axis extending along the direction in which the movable beam extends, in the direction in which the spring portion bends. Item 13. The electrostatic actuator according to any one of Items 7 to 12, which is located.

16. The second unit drive element has four pairs of comb-shaped electrodes, and the four pairs of comb-shaped electrodes pass through an axis extending along the direction in which the movable beam extends and are perpendicular to a plane orthogonal to the direction in which the spring portion bends. , Located in plane symmetry, the seventh
Item 13. The electrostatic actuator according to any one of items 12 to 12.

17. The third unit driving element has at least two pairs of comb-shaped electrodes, each pair of comb-shaped electrodes has a plurality of teeth, and the teeth of one comb-shaped electrode enter between the teeth of the other comb-shaped electrode. The teeth of each pair of comb-shaped electrodes extend along a direction orthogonal to the direction in which the movable beam extends, and the two pairs of comb-shaped electrodes are symmetrically displaced from an axis extending along the direction in which the movable beam extends. Located, seventh
Item 13. The electrostatic actuator according to any one of items 12 to 12.

18. The third unit driving element has four pairs of comb-shaped electrodes, and the four pairs of comb-shaped electrodes are axially symmetric with respect to an axis extending along the direction in which the movable beam extends. Item 13. An electrostatic actuator according to any one of Items 12 to 12.

19. 19. The electrostatic actuator according to any one of Items 1 to 18, wherein the electrostatic actuator is made of silicon having an interstitial oxygen concentration of 10 ppma (OLD ASTM) or more.

20. 20. The method for manufacturing an electrostatic actuator according to item 19, wherein the initial interstitial oxygen concentration contained in the silicon substrate is in the range of 10 to 28 ppma (OLD ASTM).

21. A mirror array driven by electrostatic force, comprising: a plurality of movable beams; a beam support unit that supports the plurality of movable beams in a cantilever manner; and a plurality of mirrors provided at respective free ends of the movable beams. Have
Each of the movable beams has a plurality of unit driving elements connected in series, and the unit driving elements include a pair of electrode supporting portions, a spring portion connecting the pair of electrode supporting portions, and an electrode supporting portion. And at least a pair of electrode elements provided on each of the mirror arrays.

22. The unit driving element has two pairs of electrode elements provided on each of the electrode support portions.
A mirror array according to the item.

23. The plurality of unit driving elements are arranged in the same direction along the direction in which the movable beam extends.
Item 23. The mirror array according to Item 1 or Item 22.

24. The plurality of unit drive elements are alternately arranged in the opposite direction along the direction in which the movable beam extends.
Item 23. The mirror array according to item 21 or 22.

25. Item 23. The mirror array according to item 21 or 22, wherein the pair of electrode elements is a pair of plate electrodes, and the pair of plate electrodes face each other at an interval.

26. Item 21. The pair of electrode elements is a pair of comb-shaped electrodes, each of the pair of comb-shaped electrodes has a plurality of teeth, and the teeth of one of the comb-shaped electrodes extend between the teeth of the other comb-shaped electrode. Or a mirror array according to item 22.

[0196]

According to the present invention, there is provided an electrostatic actuator which has a large movable range and whose displacement can be accurately controlled by an applied voltage. According to the present invention,
There is provided a mirror array in which the movable range of the direction of the mirror is widened and the direction of the mirror can be accurately controlled by an applied voltage.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of an electrostatic actuator according to a first embodiment of the present invention.

FIG. 2 schematically shows a plurality of unit drive elements connected in series included in the movable beam shown in FIG. 1;

FIG. 3 is an enlarged perspective view showing a part of the movable beam shown in FIG. 1;

FIG. 4 is a partial sectional perspective view of a part of the movable beam shown in FIG. 3;

FIG. 5 is an enlarged perspective view showing a part of a movable beam and a beam support shown in FIG. 1;

FIG. 6 is a cutaway view of a part of the beam support shown in FIG. 5;

FIG. 7 is a diagram for explaining the operation of the electrostatic actuator according to the first embodiment.

FIG. 8 is a diagram for explaining the method of manufacturing the movable beam of the electrostatic actuator according to the first embodiment, and shows a first step.

FIG. 9 is a view for explaining a method of manufacturing a movable beam of the electrostatic actuator according to the first embodiment, and
The next step following the step is shown.

FIG. 10 is a view for explaining the method of manufacturing the movable beam of the electrostatic actuator according to the first embodiment, and shows a next step following the step of FIG. 9;

FIG. 11 is a view for explaining the method of manufacturing the movable beam of the electrostatic actuator according to the first embodiment, and shows a next step following the step of FIG. 10;

FIG. 12 is a view for explaining the method of manufacturing the movable beam of the electrostatic actuator according to the first embodiment, and shows a next step following the step of FIG. 11;

FIG. 13 is a view for explaining the method of manufacturing the movable beam of the electrostatic actuator according to the first embodiment, and shows a next step following the step of FIG. 12;

FIG. 14 is a view for explaining the method of manufacturing the movable beam of the electrostatic actuator according to the first embodiment, and shows a next step following the step in FIG. 13;

FIG. 15 is a view for explaining the method of manufacturing the movable beam of the electrostatic actuator according to the first embodiment, and shows a last step following the step of FIG. 14;

FIG. 16 is a diagram for explaining a method of manufacturing the beam support portion of the electrostatic actuator according to the first embodiment,
14 illustrates a step corresponding to the step in FIG. 13.

FIG. 17 is a diagram for explaining a method of manufacturing the beam support portion of the electrostatic actuator according to the first embodiment,
16 shows a step corresponding to the step shown in FIG. 15.

FIG. 18 is a perspective view partially showing a movable beam of an electrostatic actuator according to a first modification of the first embodiment.

FIG. 19 is a perspective view partially showing a movable beam of an electrostatic actuator according to a second modification of the first embodiment.

20 schematically shows a plurality of unit drive elements connected in series included in the movable beam shown in FIG. 19;

FIG. 21 is a perspective view partially showing a movable beam of the electrostatic actuator according to the second embodiment of the present invention.

FIG. 22 is a perspective view of one first unit driving element shown in FIG. 21;

FIG. 23 is a partial sectional perspective view of the first unit drive element shown in FIG. 22;

FIG. 24 is a perspective view of one second unit drive element shown in FIG. 21;

FIG. 25 is a partial sectional perspective view of the second unit driving element shown in FIG. 24;

FIG. 26 is a perspective view of one third unit driving element shown in FIG. 21;

FIG. 27 is a partial sectional perspective view of the third unit drive element shown in FIG. 26;

FIG. 28 is a diagram for explaining the operation of the first unit driving elements shown in FIGS. 22 and 23, and is a side view of four first unit driving elements connected in series.

FIG. 29 is a diagram for explaining the operation of the second unit drive element shown in FIGS. 24 and 25, and is a plan view of four second unit drive elements connected in series.

FIG. 30 is a view for explaining the operation of the third unit drive element shown in FIGS. 26 and 27, and is a cross-sectional view taken along the axis of the movable beam.

FIG. 31 shows a configuration of a CMOS circuit formed inside the first to third driving elements.

FIG. 32 is a diagram for explaining the method of manufacturing the movable beam of the electrostatic actuator according to the second embodiment, and shows a first step.

FIG. 33 is a view for explaining the method for manufacturing the movable beam of the electrostatic actuator according to the second embodiment, and shows the next step following the step in FIG. 32.

FIG. 34 is a view for explaining the method for manufacturing the movable beam of the electrostatic actuator according to the second embodiment, and shows the next step following the step in FIG. 33.

FIG. 35 shows the structure shown in FIG. 34 with a partial cutaway.

FIG. 36 is a view for explaining the method for manufacturing the movable beam of the electrostatic actuator according to the second embodiment, and shows the next step following the step in FIG. 34.

FIG. 37 is a view for explaining the method for manufacturing the movable beam of the electrostatic actuator according to the second embodiment, and shows the next step following the step in FIG. 36.

38 is a diagram for explaining the method for manufacturing the movable beam of the electrostatic actuator according to the second embodiment, and shows the next step following the step in FIG. 37. FIG.

FIG. 39 is a view for explaining the method for manufacturing the movable beam of the electrostatic actuator according to the second embodiment, and shows the next step following the step in FIG. 38.

40 is a diagram for explaining the method for manufacturing the movable beam of the electrostatic actuator according to the second embodiment, and shows a last step following the step in FIG. 39.

FIG. 41 is a perspective view of a movable beam of the electrostatic actuator of the second embodiment completed through the steps of FIGS. 32 to 40;

FIG. 42 is a perspective view partially showing a mirror array according to the third embodiment of the present invention.

43 is an enlarged view of the movable beam and the beam support shown in FIG. 42, and shows the beam support in a partially broken manner.

FIG. 44 is a diagram for explaining a method for manufacturing a movable beam and a mirror of the mirror array according to the third embodiment, and shows a first step.

FIG. 45 is a view for explaining the method of manufacturing the movable beam and the mirror of the mirror array according to the third embodiment, and shows the next step following the step in FIG. 44.

FIG. 46 is a view illustrating the method for manufacturing the movable beam and the mirror of the mirror array according to the third embodiment, and shows the next step following the step in FIG. 45.

FIG. 47 is a view for explaining the method for manufacturing the movable beam and the mirror of the mirror array according to the third embodiment, and shows the next step following the step in FIG. 46.

FIG. 48 is a view illustrating the method for manufacturing the movable beam and the mirror of the mirror array according to the third embodiment, and shows a last step following the step in FIG. 47.

FIG. 49 is a perspective view of a movable beam and a mirror of the mirror array of the third embodiment completed through the steps of FIGS. 44 to 48;

FIG. 50 is a perspective view partially showing a mirror array according to the fourth embodiment of the present invention.

FIG. 51 shows a partially enlarged view of the movable beam shown in FIG. 50;

FIG. 52 shows the movable beam shown in FIG. 51 in a partially broken manner.

FIG. 53 shows a configuration of a known spectroscope.

54 is a cutaway perspective view showing a basic structure of a DMD (Digital Micromirror Device) applicable to the spatial light modulator shown in FIG. 53.

FIG. 55 is a view for explaining the operation principle of the DMD shown in FIG. 54;

FIG. 56 shows a preferable arrangement relationship of a spatial light modulator with respect to light projected by a prism in a spectroscopic device.

FIG. 57 shows a spatial light modulator in which a mirror is changed to a strip-shaped elongated mirror to reduce scattered light.

FIG. 58 shows a basic structure of a drive mechanism for driving a mirror of the spatial light modulator shown in FIG. 57.

FIG. 59 shows a configuration necessary for simultaneously detecting a plurality of lights having different wavelengths.

FIG. 60 shows the configuration of the simplest electrostatic actuator.

FIG. 61 is a view for explaining the operation of the electrostatic actuator shown in FIG. 60;

FIG. 62 is a perspective view of a known electrostatic actuator having a large stroke.

63 is a diagram for explaining the operation of the electrostatic actuator shown in FIG. 62, and shows a state immediately after a voltage is applied.

64 is a diagram for explaining the operation of the electrostatic actuator shown in FIG. 62, and shows a state where the first drive electrode appearing next to the state in FIG. 63 is in contact with the substrate.

FIG. 65 is a view for explaining the operation of the electrostatic actuator shown in FIG. 62, and shows a state in which the second drive electrode appearing next to the state in FIG. 64 is in contact with the substrate;

FIG. 66 is a view for explaining the operation of the electrostatic actuator shown in FIG. 62, and shows a state in which all drive electrodes are in contact with the substrate.

[Explanation of symbols]

 102 movable beam 104 beam support unit 110 unit drive element 112 first electrode support unit 114 second electrode support unit 116 spring unit 122a, 122b ground electrode 124a, 124b drive electrode

Claims (3)

[Claims] 1. An electrostatic actuator driven by electrostatic force, comprising: a movable beam; and a beam supporter for supporting the movable beam in a cantilever manner, wherein the movable beams are connected in series. A plurality of unit driving elements, the unit driving elements each including a pair of electrode supporting portions, a spring portion connecting the pair of electrode supporting portions, and at least a pair of electrode elements provided on each of the electrode supporting portions; An electrostatic actuator having: 2. The electrostatic actuator according to claim 1, wherein the unit drive element has two pairs of electrode elements provided on each of the electrode support portions. 3. A mirror array driven by electrostatic force, comprising: a plurality of movable beams; a beam supporter for supporting the plurality of movable beams in a cantilever manner; and a free end of each of the movable beams. Each of the movable beams has a plurality of unit driving elements connected in series, and the unit driving elements have a pair of electrode support portions and a pair of electrode support portions. And a mirror array having at least a pair of electrode elements provided on each of the electrode support portions.