JP5256914B2 - MICROSTRUCTURE, MICRO DEVICE COMPRISING THE STRUCTURE, AND METHOD FOR PRODUCING MICROSTRUCTURE - Google Patents

Description

The present invention has, for example, a rotationally displaceable swinging part manufactured by processing an SOI (silicon on insulator) substrate formed by laminating two or more silicon layers with at least one insulating layer interposed therebetween. The present invention relates to a micro structure, a micro element including the micro structure, and a method for manufacturing the micro structure .

  2. Description of the Related Art In recent years, various microstructures having a swingable swingable portion manufactured by processing an SOI substrate have been proposed. For example, a micro-mirror element having a light reflection function as shown in FIG. 21 by processing an SOI substrate by a micromachining technique has been proposed (for example, Japanese Patent Laid-Open No. 2006-162663). FIG. 21 is a perspective view of the micromirror element as viewed obliquely from above. 22 is an enlarged perspective view of the torsion bar portion of the micromirror element, and FIG. 23 is a cross-sectional view taken along line AA of FIG.

  In the micromirror element 100 shown in FIG. 21, a circular mirror 103 is provided on one side of an arm 102, and a swing member having a plurality of comb electrodes 104 arranged in a row on the other side of the arm 102 is used as a mirror of the arm 102. 103, and a pair of V-shaped torsion bars 105 and 105 ′ between the comb electrode 104 and the comb-shaped electrode 104. The micromirror element 100 is supported in a swingable manner on the upper region 101A of the frame 101 in the height direction. ing. In the lower region 101B of the frame 101, a plurality of comb electrodes 106 are formed in a portion facing the plurality of comb electrodes 104 so that each comb electrode is positioned in a gap between the plurality of comb electrodes 104. ing. In FIG. 21, the upper region 101 </ b> A of the frame 101 is drawn with an alternate long and short dash line so that the contents inside the frame 101 can be understood.

  Therefore, the micromirror element 100 generates an electrostatic force (attractive force) between the comb-tooth electrode 104 and the comb-tooth electrode 106 by applying a voltage between the comb-tooth electrode 104 and the comb-tooth electrode 106. By pulling the other end of the arm 102 downward by an electrostatic force, the arm 102 is rotated in the vertical direction about the torsion bars 105 and 105 ′ as a rotation axis, whereby the mirror surface 103A of the mirror 103 is slightly changed. It has become.

  When the micromirror element 100 is manufactured by processing the SOI substrate by micromachining technology, the upper silicon layer of the SOI substrate in which an insulating layer is formed between the two silicon layers (see the silicon layer SL1 in FIGS. 22 and 23). ), The silicon layer is dug from the surface to form the arm 102, the mirror 103, the plurality of comb electrodes 104, and the torsion bar 105, and the lower silicon layer (see the silicon layer SL2 in FIGS. 22 and 23). ), The silicon layer is dug down from the surface (surface Sb in FIG. 23) to form a plurality of comb electrodes 106. Finally, in order to make the unnecessary portions (the arm 102, the mirror 103, and the plurality of comb electrodes 104) of the insulating layer (see the insulating layer BOX in FIGS. 22 and 23) swingable in the height direction of the frame 101, The portion that must penetrate the front and back surfaces in the frame 101 (see the portion 109A shown by the dotted line in FIG. 22) is removed to complete the micromirror device 100.

JP 2006-162663 A Japanese Patent Laid-Open No. 10-190007

  Incidentally, in the micromirror element 100 shown in FIG. 21, the arm 102 is supported by a pair of V-shaped torsion bars 105 and 105 ′ so as to be twistable on the inner surface of the frame 101, and the pair of torsion bars 105 and 105 ′ is supported. Since the angle of the mirror surface 103A of the mirror 103 is minutely changed by swinging the arm 102 as the swing axis, the mechanical characteristics of the pair of torsion bars 105, 105 ′, particularly the torsion bars 105, 105 ′. The mechanical resonance characteristics of the torsion bars 105 and 105 ′ when the action of the torsional force and the release of the torsional force are repeated at high speed greatly affect the angle control of the mirror surface 103A of the mirror 103.

  Therefore, after processing a single SOI substrate to manufacture a plurality of micromirror elements 100, the positions and shapes of the torsion bars 105, 105 ′ in the height direction of the SOI substrate are measured, and based on the measurement results. The characteristics of the micromirror element 100 manufactured by each SOI substrate are grasped.

  As shown in FIG. 23, the positional information of the torsion bars 105 and 105 ′ in the height direction of the SOI substrate is obtained from the surface Sa of the SOI substrate to the torsion bars 105 and 105 ′ using the surface Sa or the back surface Sb of the SOI substrate as a reference surface. The distance d1 to the front surface St or the distance d2 from the back surface Sb of the SOI substrate to the surface St of the torsion bar 105 is obtained, and the shape information of the torsion bar 105 is the distance d1 or the distance d2 at a plurality of positions on the torsion bar 105. The torsion bars 105 and 105 ′ of the plurality of micromirror elements 100 manufactured on the SOI substrate are in a state of floating in the height direction of the SOI substrate. One of the plurality of micromirror elements 100 formed It is difficult to accurately measure the position and shape of the 105 and 105 '.

  Therefore, conventionally, a dummy torsion bar 110 having the same shape as the torsion bars 105 and 105 ′ that are actually manufactured is formed in an area where the micromirror element 100 of the SOI substrate is not manufactured, and the dummy torsion bar 110 is used to perform SOI. The distance d1 or d2 from the front surface Sa or the back surface Sb of the substrate is measured.

  The shape of the dummy torsion bar 110 is V-shaped like the torsion bar 105, but the dummy torsion bar 110 does not float in the air as shown in FIG. The base 111 is left and formed on it. Therefore, in the position measurement using the dummy torsion bar 110, the level difference d3 between the surface Sc of the base 111 and the surface St of the dummy torsion bar 110 is measured at a plurality of locations on the dummy torsion bar 110, and the height of the base 111 is measured at each level difference d3. The distance d2 from the back surface Sb of the SOI substrate is calculated by adding d4.

  By the way, in the SOI substrate for manufacturing the micromirror element 100, for example, the thickness of the upper silicon layer SL1 is about 100 μm, the thickness of the lower silicon layer SL2 is about several hundred μm, and the thickness of the intermediate insulating layer BOX is several. Since it is a very thin substrate of about μm, the distance d1 or the distance d2 measured by the position measurement of the torsion bars 105, 105 ′ in the height direction of the SOI substrate is a minute dimension on the order of μm.

  Therefore, in measuring the position of the torsion bars 105 and 105 ', an error of several μm becomes a measurement error of several to tens of percent, and thus very high accuracy is required. However, in the conventional position measurement of the torsion bars 105 and 105 ′, the positions of the torsion bars 105 and 105 ′ of the plurality of actually manufactured micromirror elements 100 are not measured. Since the measurement is performed indirectly using the dummy torsion bar 110 manufactured at a position different from the position, there is a problem that the accuracy of position measurement and shape measurement of the torsion bars 105 and 105 ′ is not sufficient.

  Note that the above problem is not limited to the micromirror element, but can be similarly applied to other micro structures such as an acceleration sensor, an angular velocity sensor, and a vibration element having a similar swinging portion using a torsion bar. .

The present invention has been made in view of the above problems, and in a microstructure having a swinging portion using a torsion bar manufactured by processing an SOI substrate, the torsion of the microstructure actually manufactured. It is an object of the present invention to provide a microstructure that can accurately measure the position and shape of a bar, a microdevice using the same, and a method for manufacturing the microstructure .

The microstructure provided by the present invention includes a frame-shaped fixing portion and a swinging portion supported in a swingable manner by a pair of torsion bars in the fixing portion, and laminates two conductor layers with an insulating layer interposed therebetween. In the microstructure manufactured by subjecting the SOI substrate to the processing for forming the fixed portion and the swinging portion, the pair of torsion bars are positioned closer to the insulating layer of one conductor layer than the conductor layer. is formed in a thin thickness, is located on the lower side of each torsion bar of the other conductor layer, the portion that does not interfere with the torsional motion of the torsion bar, provided structure having the conductive layer and the same thickness, respectively, the The surface of the structure facing the torsion bar is used as a reference surface for measuring the distance to the upper surface of the torsion bar .

  According to the present invention, the structure having the same thickness as that of the conductor layer is provided on the portion of the other conductor layer located below each torsion bar and not interfering with the twisting operation of the torsion bar. The surface of the structure facing the torsion bar is used as a reference surface at a position in the thickness direction of one conductor layer of the torsion bar, so that a process of forming a fixed portion and a swing portion on the SOI substrate is performed. In the process of manufacturing, the position of the torsion bar of the microstructure formed on the SOI substrate in the thickness direction of the SOI substrate is measured as the position from the reference plane of the structure, and the measurement result is used, for example, SOI By calculating the position of the torsion bar from the front or back surface of the substrate, the position and shape of the torsion bar can be measured with high accuracy. That.

  As a result, it is possible to grasp the resonance characteristics based on the position and shape of the torsion bar of the microstructure manufactured using each SOI substrate with high accuracy.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  The micro structure according to the present invention will be described using a micro mirror element as an example.

  FIG. 1 is a perspective view showing a micromirror element according to the present invention. FIG. 2 is a perspective view showing a portion of the structure provided in the micromirror element. 3A is a view of the torsion bar portion of the micromirror element as viewed from above, and FIG. 3B is a cross-sectional view taken along the line III-III in FIG. 4 and 5 are diagrams showing the manufacturing process of the micromirror element, and FIG. 6 is a diagram showing a method for measuring the position of the torsion bar of the micromuller element.

  The micromirror element 1 includes a frame 2 having a rectangular frame shape in plan view, and an oscillation shaft 32 extending on the major axis of an elliptical mirror portion 31, and a plurality of combs at the tip of the oscillation shaft 32. The swing member 3 is provided with tooth electrodes 33 protruding in a row. The swing member 3 is supported on the inner side of the frame 2 by a pair of V-shaped torsion bars 4, 4 ′ so as to be swingable.

  The frame 2 is divided into two regions in the height direction, and the swing member 3 is arranged in the upper region 2A in the frame 2. On the other hand, a plurality of comb-shaped electrodes 21 project from the inner surface of the lower region 2 </ b> B of the frame 2 and face the plurality of comb-shaped electrodes 33 of the swing member 3. The plurality of comb-shaped electrodes 21 are located at substantially the center of the gap between the plurality of comb-shaped electrodes 33. In FIG. 1, the upper region 2 </ b> A of the frame 2 is drawn with a one-dot chain line so that the contents inside the frame 2 can be understood.

  The dimension L3 of the thickness of the frame 2 is, for example, 5 to 50 μm, and the dimension H in the height direction is, for example, about 600 μm.

  As will be described later, the micromirror element 1 includes, for example, two silicon layers 61, sandwiching an insulating film (BOX (Buried Oxide) layer) 63 by bulk micromachining technology such as MEMS (Micro Electro Mechanical Systems) technology. This is manufactured by processing the SOI substrate 6 on which 62 is laminated (see FIGS. 4 and 5). The two silicon layers 61 and 62 of the SOI substrate 6 have conductivity by doping impurities.

  The swing member 3 is formed by processing a silicon layer 61 on the surface side of the SOI substrate 6 (hereinafter referred to as “first silicon layer 61”). Accordingly, the region corresponding to the first silicon layer 61 of the frame 2 is the upper region 2A. The plurality of comb electrodes 21 of the frame 2 are formed by processing a silicon layer 62 on the back surface side of the SOI substrate 6 (hereinafter referred to as “second silicon layer 62”). Therefore, a region corresponding to the second silicon layer 62 and the insulating film 63 of the frame 2 is the lower region 2B.

  The mirror part 31 has an elliptical plate shape having substantially the same thickness as the first silicon layer 61. A mirror surface 311 is formed on the surface of the elliptical plate. A dimension L1 in the minor axis direction of the mirror part 31 is, for example, 20 to 300 μm.

  On the other hand, the swing shaft 32 is a strip-shaped plate material having substantially the same width as the first silicon layer 61. The swing shaft 32 is extended to the mirror portion 31 such that the width direction of the plate material coincides with the height direction of the mirror portion 31 (vertical direction in FIG. 1). A dimension L2 in the height direction of the swing shaft 32 is, for example, 10 to 100 μm.

  The plurality of comb-teeth electrodes 33 are rectangular piece members having substantially the same width as the first silicon layer 61. The plurality of comb-teeth electrodes 33 are provided so as to project toward the side surfaces on the long side of the frame 2 with predetermined intervals on both surfaces of the swing shaft 32. The plurality of comb electrodes 33 projecting from one surface of the swing shaft 32 are paired with the plurality of comb electrodes 33 projecting from the other surface.

  On the other hand, the plurality of comb electrodes 21 are rectangular piece members having substantially the same width as the second silicon layer 62. The plurality of comb-shaped electrodes 21 are provided so as to protrude toward the swing shaft 32 at the same inner spacing along the long side of the frame 2 as the spacing between the comb-shaped electrodes 33. Each comb-tooth electrode 21 is arranged so as to be positioned at the center of each interval of the comb-tooth electrode 33.

  The pair of torsion bars 4, 4 ′ has a shape in which rod members having a rectangular cross section are connected in a V shape. The pair of torsion bars 4, 4 ′ is a predetermined position between the mirror portion 31 of the swing shaft 32 and the comb-shaped electrode 33 closest to the mirror portion 31 (the center of gravity position M of the swing member 3 or a position in the vicinity thereof). ). Each torsion bar 4, 4 ′ has a V-shaped open side connected to the side surface of the swing shaft 32 and a V-shaped narrowed side connected to the side surface of the frame 2. Each torsion bar 4, 4 ′ has a thickness that is shorter than the dimension in the height direction of the swing shaft 32, and is provided at a position near the lower side (position close to the insulating film 63) in the height direction of the swing shaft 32. (See FIG. 2).

  The comb electrode 33 is a portion to which a drive voltage (DC voltage) for swinging the swing shaft 32 is applied. The comb electrode 33 functions as an electrode due to the conductivity of the first silicon layer 61. Since the mirror portion 31, the swing shaft 32, the plurality of comb electrodes 33, and the pair of torsion bars 4, 4 ′ are integrally formed by a first silicon layer 61 having conductivity as described later, these When a voltage is applied to any of the members, a voltage is applied to the plurality of comb electrodes 33. Similarly, the comb electrode 21 is a portion to which a drive voltage for swinging the swing shaft 32 (voltage having a polarity opposite to that of the comb electrode 33) is applied. The comb electrode 21 functions as an electrode due to the conductivity of the second silicon layer 62.

  The first silicon layer 61 and the second silicon layer 62 are electrically insulated by an insulating film 63. Therefore, even if a driving voltage is applied between the swing member 3 formed on the first silicon layer 61 and the frame 2 formed on the second silicon layer 62, the comb-tooth electrode 21 and the swing member of the frame 2 are applied. The third comb-teeth electrode 33 is not short-circuited, and a potential difference based on the drive voltage is generated between the two electrodes. Then, an electrostatic force attracting each other is generated between the comb electrode 21 and the swing member 3 due to the potential difference, and the comb electrode 33 of the swing member 3 is lowered to the lower region 2B by this electrostatic force, and the mirror portion 31 is moved. It rises above the upper region 2A. The pair of torsion bars 4, 4 ′ are twisted due to the lowering of the comb electrode 33 to the lower region 2 </ b> B, and a restoring force due to the twist acts on the swing member 3. Therefore, the comb electrode 33 is lowered to a position where the restoring force and the electrostatic force are balanced. Since the electrostatic force is proportional to the drive voltage, the descending amount of the comb electrode 33 changes in accordance with the magnitude of the drive voltage. As a result, the horizontal surface of the mirror surface 311 of the mirror portion 31 (the surface along the insulating film 63). The inclination angle θ changes.

  On the other hand, when the drive voltage is no longer applied, the electrostatic force generated between the comb electrode 21 and the comb electrode 33 disappears. Therefore, the comb electrode 33 returns to the original position by the restoring force of each torsion bar 4, 4 ′, and the mirror surface 311 of the mirror portion 31 returns to the horizontal position. As a result, by changing the driving voltage including 0 [V] continuously or stepwise, the inclination angle θ of the mirror surface 311 of the mirror unit 31 with respect to the horizontal plane changes continuously or stepwise.

  As shown in FIG. 1, the angle control of the mirror surface 311 of the micromirror element 1 is performed by connecting a drive circuit 7 for applying a drive voltage between the frame 2 and the swing member 3, and driving from the drive circuit 7. This is done by controlling the voltage value by the control circuit 8. The tilt angle of the mirror surface 311 is set in multiple stages at a predetermined pitch, a control signal corresponding to the tilt angle θ of each stage is set, and the control signal is output from the control circuit 8 to the drive circuit 7. Thus, the tilt angle θ of the mirror surface 311 of the micromirror element 1 is controlled.

  When the control circuit 8 changes the drive voltage from the drive circuit 7 at high speed, the swing member 3 vibrates at high speed in the direction indicated by the arrow R in FIG. The vibration characteristic of the swing member 3 at this time depends on the resonance characteristic against torsion based on the mechanical structure of the pair of torsion bars 4 and 4 ′. The resonance characteristics vary greatly depending on the V shape of each torsion bar 4, 4 ′ formed by processing the SOI substrate 6 and the position of the SOI substrate 6 in the height direction. Therefore, in the present embodiment, in order to be able to accurately measure the position of each torsion bar 4, 4 ′ in the height direction of the micromirror element 1, as shown in FIG. Structures 5 and 5 ′ are provided on the lower side of the bars 4 and 4 ′ to provide reference positions Sr for position measurement, respectively. 1 and 2, the structure 5 'is not visible. Moreover, in FIG. 2, in order to make the structure 5 easy to see, the portion of the frame 2 is saved.

  Each structure 5, 5 'has a triangular prism shape. The shape of the triangular prism of one structure 5 in plan view (cross-sectional shape along the insulating layer 63) is substantially the same as the triangle surrounded by the torsion bar 4 and the swing shaft 32, as shown in FIG. It has become. Accordingly, one structure 5 is provided in the second silicon layer 62 so as to be positioned below the triangular space K surrounded by the torsion bar 4 and the swing shaft 32. As shown in FIG. 3B, the upper surface S1 of the structure 5 coincides with the boundary surface Sp between the second silicon layer 62 and the insulating layer 63, and the lower surface S2 of the structure 5 is an opening of the second silicon layer 62. It corresponds to the surface (the lower surface in FIG. 3B) Sq. The upper surface S1 of the structure 5 serves as a reference surface Sr that is fixed in position in the height direction of the micromirror element 1 of the torsion bar 4. The other structure 5 ′ has the same configuration as that of the one structure 5 described above.

  Next, a method for manufacturing the micromirror element 1 shown in FIG. 1 will be described with reference to FIGS.

  The manufacturing method of the micromirror element 1 shown in FIGS. 4 and 5 is one method for manufacturing a microstructure using a bulk micromachining technique. 4 and 5, the mirror support M, the swing axis AR, the frames F1 and F2, the torsion bars T1 and T2, the pair of comb electrodes E1 and E2, and the structure G shown in FIG. The formation process is expressed as a change in one cross section. This one cross section is a model of a cross section of a plurality of predetermined portions included in a single micromirror element formation section on a material substrate (a wafer having a multilayer structure) to be processed, and is represented as a continuous cross section. is there. The mirror support part M corresponds to a part of the mirror part 31. The swing axis AR corresponds to the swing shaft 32 and represents a cross section of the swing shaft 32. Frames F <b> 1 and F <b> 2 respectively correspond to frame 2 and represent a cross section of frame 2. The torsion bar T1 corresponds to the torsion bar 4 and represents a cross section in the extending direction of the torsion bar 4. The torsion bar T2 corresponds to the torsion bar 4 'and represents a cross section of the torsion bar 4'. The comb electrode E1 corresponds to a part of the comb electrode 33, and represents a cross section of the electrode teeth. The comb-tooth electrode E2 corresponds to a part of the comb-tooth electrode 21 and represents a cross section of the electrode teeth.

  In manufacturing the micromirror element 1, first, a material substrate 6 as shown in FIG. The material substrate 6 is an SOI substrate having a laminated structure including a first silicon layer 61, a second silicon layer 62, and an insulating layer 63 between the silicon layers 61 and 62. The first silicon layer 61 and the second silicon layer 62 are made of a silicon material imparted with conductivity by doping impurities. As the impurities, p-type impurities such as B and n-type impurities such as P and Sb can be employed. The insulating layer 63 is made of, for example, silicon oxide. The thickness h1 of the first silicon layer 61 is, for example, 10 to 100 μm, the thickness h2 of the second silicon layer 62 is, for example, 50 to 500 μm, and the thickness h3 of the insulating layer 63 is, for example, 0 .3 to 3 μm.

  Next, as illustrated in FIG. 4B, a mirror surface 311 is formed on the first silicon layer 61. In forming the mirror surface 311, for example, Cr (50 nm) is deposited on the surface of the first silicon layer 61 by sputtering, and then Au (200 nm) is deposited thereon. Next, the mirror surface 311 is patterned by sequentially performing an etching process on these metal films through a predetermined mask. As an etching solution for Au, for example, a potassium iodide-iodine aqueous solution can be used. As an etchant for Cr, for example, an aqueous solution of ceric ammonium nitrate can be used.

  Next, as shown in FIG. 4C, an oxide film pattern 64 and a resist pattern 65 are formed on the first silicon layer 61, and an oxide film pattern 66 is formed on the second silicon layer 62. The oxide film pattern 64 has a pattern shape corresponding to the swing member 3 (mirror support part M, swing axis AR, comb electrode E1) and frame 2 (frames F1, F2). The resist pattern 65 has a pattern shape corresponding to both torsion bars 4, 4 '(torsion bars T1, T2). The oxide film pattern 66 has a pattern shape corresponding to the frame 2 (frames F1 and F2), the comb electrode 21 (comb electrode E2), and the structures 5 and 5 '(structure G).

  Next, as shown in FIG. 4D, the first silicon layer 61 is etched to a predetermined depth by DRIE (deep reactive ion etching) using the oxide film pattern 64 and the resist pattern 65 as a mask. The predetermined depth is a depth corresponding to the thickness of the torsion bars T1 and T2, for example, 5 μm. In DRIE, a good etching process can be performed in a Bosch process in which etching and sidewall protection are alternately performed. Such a Bosch process can also be adopted for the later DRIE.

  Next, as shown in FIG. 5A, the resist pattern 65 is peeled by applying a stripping solution. As the stripper, for example, AZ remover 700 (manufactured by Clariant Japan) can be used.

  Next, as shown in FIG. 5B, the oxide film pattern 64 is used as a mask to etch the first silicon layer 61 up to the insulating layer 63 while remaining the torsion bars T1 and T2 by DRIE. I do. By this etching process, the swing member 3 (mirror support part M, swing axis AR, comb electrode E1), both torsion bars 4, 4 '(torsion bars T1, T2), and frame 2 (frames F1, F2) ) Is molded.

  Next, as shown in FIG. 5C, the second silicon layer 62 is etched by DRIE until the insulating layer 63 is reached using the oxide film pattern 66 as a mask. By this etching process, a part of the frame 2 (frames F1 and F2), the comb electrode 21 (comb electrode E2), and the structures 5 and 5 '(structure G) are formed.

Next, as shown in FIG. 5D, the exposed portions of the insulating layer 63 and the oxide film patterns 64 and 66 are removed by etching. As an etching method, dry etching or wet etching can be employed. When dry etching is employed, for example, CF ₄ or CHF ₃ can be employed as the etching gas. When wet etching is employed, for example, buffered hydrofluoric acid (BHF) made of hydrofluoric acid and ammonium fluoride can be used as the etchant.

  Through the above series of steps, the mirror support portion M, the swing axis AR, the frames F1 and F2, the torsion bars T1 and T2, the pair of comb electrodes E1 and E2, and the structure G are formed to form a micromirror. Element 1 is manufactured.

  The positions of the torsion bars 4 and 4 ′ in the height direction of the micromirror element 1 are as shown in FIG. 3B from the lower surface of the frame 2 (corresponding to the lower surface S 2 of the structure 5) to the torsion bars 4 and 4. It is calculated | required as distance Lt to the upper surface St of '. For example, the distance Lt is expressed as Lt = h2 + Lt2 where the thickness of the second silicon layer 62 is h2 and the distance from the reference surface Sr of the structure 5 to the upper surface St of the torsion bar 4 is Lt2. Since the thickness h2 of the second silicon layer 62 of the SOI substrate 6 is known, if the distance Lt2 can be measured accurately, the distance Lt can be obtained accurately.

  In this embodiment, the structures 5 and 5 ′ that give the reference surface Sr to the micromirror element 1 actually formed on the SOI substrate 6 are formed. Therefore, for example, as shown in FIG. 6A, the measurement line N is irradiated with laser light, and the distance D from the laser irradiation position to the reflection surface is measured by the reflected light, and the measurement result is used. The distance Lt is measured. Specifically, a waveform as shown in FIG. 5B is acquired, the distance Lt2 is accurately measured from the step of the waveform, and the thickness h2 of the second silicon layer 62 measured in advance at this measured value Lt2. Are added to measure the measured value Lt of the position of each torsion bar 4, 4 ′ in the height direction of the frame 2.

  As described above, in this embodiment, the positions of the pair of torsion bars 4 and 4 ′ in the height direction of the micromirror elements 1 are measured on all of the plurality of micromirror elements 1 formed on the SOI substrate 6. A pair of structures 5 and 5 ′ for providing the reference plane Sr are integrally formed. Therefore, with respect to some micromirror elements 1 of the plurality of micromirror elements 1 formed on the same SOI substrate 6, the torsion bar 4 using the reference surface Sr of the structures 5 and 5 ′ for each micromirror element 1. By measuring the position 4 ′, the positions of the torsion bars 4 and 4 ′ can be accurately measured. And the resonance characteristic of the torsion bars 4 and 4 ′ of the plurality of micromirror elements 1 formed on the same SOI substrate 6 can be accurately grasped using the measured value.

  The pair of structures 5 and 5 ′ has a function of providing a measurement reference plane Sr when measuring the position of the pair of torsion bars 4 and 4 ′ in the height direction of the micromirror element 1 as described above. It only fulfills. The pair of structures 5 and 5 ′ are not related to the original functional operation of each micromirror element 1 (operation to change the tilt angle θ of the mirror surface 311 by swinging the swinging member 3). Rather, the structures 5 and 5 ′ are provided below the torsion bars 4 and 4 ′, respectively, and therefore must not interfere with the torsion of the torsion bars 4 and 4 ′ during the swinging motion of the swinging member 3. It is necessary to arrange so that.

Therefore, for structure 5,
(1) Processing the second silicon layer 62 of the SOI substrate 6 to form at least the boundary surface Sp of the second silicon layer 62;
(2) It is formed at a position below each torsion bar 4 and 4 'so as not to interfere with the twist of each torsion bar 4 and 4'.
The structure shown in FIG. 2 is not limited as long as the above condition is satisfied.

  For example, in the present embodiment, each torsion bar 4, 4 ′ has a V shape, and thus the cross-sectional shape of each structure 5, 5 ′ is substantially the same as the triangular space K. It is not necessary to match the cross-sectional shape of the structures 5 and 5 ′ with the triangular space K. For example, the cross-sectional shape of each structural body 5, 5 ′ may be trapezoidal.

Further, as shown in FIG. 7, the structure 5 may be configured by a pair of plate members 5 </ b> A and 5 </ b> B along the outer shape of the torsion bar 4 at the lower portion outside the V-shaped torsion bar 4. In this case, the upper surfaces S _5A and S _5B of the plate members 5A and 5B function as the reference surface Sr. Furthermore, as shown in FIG. 8, the structure 5 may have a configuration in which the configuration in FIG. 2 and the configuration in FIG. 7 are combined. In this case, the upper surfaces S _5A , S _5B and S _{5C of} the outer plate members 5A and 5B and the inner triangular prism member 5C function as the reference surface Sr. The same applies to the structure 5 ′. In FIGS. 7A and 8A, the portion of the frame 2 is omitted in order to make the structures 5A to 5C easier to see.

  The structures 5 and 5 ′ are not necessarily necessary elements from the viewpoint of the components that vibrate the mirror surface 311 of the micromirror element 1. Therefore, it is preferable to make the structures 5 and 5 ′ as light as possible and to reduce the influence on the vibration characteristics of the mirror surface 311 as much as possible.

  For this purpose, for example, as shown in FIG. 9, the inside of the triangular prism-like structure 5 may be penetrated from the surface Sq side of the second silicon layer 62 to form a cylinder. The cylindrical structure 5 can be formed by applying a two-stage DRIE (deep reactive ion etching) process to the second silicon layer 62. The same applies to the structure 5 '. In addition, FIG. 9 is drawn from the bottom side in order to make the hole of the structure 5 easy to see. Further, in order to make the structure 5 easy to see, the portion of the frame 2 is omitted.

  By the way, when manufacturing the micromirror element 1 by processing the SOI substrate 6, the loading effect (the removal rate of the first silicon layer 61 becomes non-uniform due to the difference in the opening area in the etching), and each torsion bar 4 , 4 ′ in order to suppress the non-uniform V-shape), as shown in FIG. 10, the top of each torsion bar 4, 4 ′ has a shape similar to that of the structures 5, 5 ′. 2 structures 7 may be formed. The second structure 7 has a triangular cross-sectional shape that is similar to the triangular space K surrounded by the torsion bar 4 and the swing shaft 32 and is smaller than the triangle.

  The structures 5 and 5 'according to the present invention are different in purpose from the second structure 7 and do not interfere with each other, so that the second structure 7 is formed as shown in FIG. It can also be formed for micromirror elements. In FIG. 10, the portion of the frame 2 is omitted in order to make the structure 5 and the second structure 7 easier to see.

  Next, application examples of the microstructure according to the present invention will be described.

  In order to realize a large-scale optical switch applied to various optical communication devices such as optical cross-connect devices, a spatial optical coupling type using multiple micro tilt mirror arrays with controllable reflection surface angles Optical switches are known. An application example of the microstructure according to the present invention is such an optical switch.

11 and 12 are diagrams showing an example of an optical switch using a micro tilt mirror array to which the microstructure according to the present invention is applied. FIG. 11 is a diagram showing a basic configuration of an optical switch using a micro tilt mirror array, and FIG. 12 is a top view of the optical switch.
It is Chi.

  The optical switch 10 includes a light input / output member 11, an input / output light reflecting mirror 12, and a folding mirror 13. The light input / output member 11 is a member in which a light input portion 11A for inputting light and a light output portion 11B for outputting light are arranged in parallel on the same plane. Each of the light input unit 11A and the light output unit 11B is provided with a collimator array. Each collimator array has a plurality of collimators arranged in a grid.

  The input / output light reflecting mirror 12 reflects the light input from the light input portion 11A of the light input / output member 11 to the folding mirror 13 side and the light returned from the folding mirror 13 to the light input / output member. 11 is a member in which the output light reflecting portion 12B that reflects to the light output portion 11B side is arranged in parallel on the same plane. Each of the input light reflecting portion 12A and the output light reflecting portion 12B is provided with a tilt mirror array. Each tilt mirror array is a plurality of micromirror elements arranged in a lattice pattern. And the micromirror element is comprised by the micromirror element 1 which concerns on this invention mentioned above. Therefore, the structures 5 and 5 ′ described above are formed in each of the plurality of micromirror elements formed in the input light reflecting portion 12 </ b> A and the output light reflecting portion 12 </ b> B.

  By changing the inclination angle of each mirror surface of the tilt mirror array provided in the input light reflecting portion 12A, the optical path of the input light reflected from the input light reflecting portion 12A to the folding mirror 13 changes. Similarly, the output light reflected from the output light reflecting portion 12B to the light output portion 11B of the light input / output member 11 by changing the inclination angle of each mirror surface of the tilt mirror array provided in the output light reflecting portion 12B. The optical path changes. Therefore, by controlling the inclination angle of each mirror surface of each tilt mirror array of the input light reflecting portion 12A and the output light reflecting portion 12B, the light input portion 11A of the light input / output member 11 can be controlled by the input / output light reflecting mirror 12. The optical path from the input light reflecting portion 12A, the folding mirror 13 and the output light reflecting portion 12B of the input / output light reflecting mirror 12 to the light output portion 11B of the light input / output member 11 is controlled. As a result, the incident position of the collimator array in the light input section 11A of the input light and the emission position of the collimator array in the light output section 11B of the light change, and the optical path is switched.

  The normal direction n1 of the light input / output surface of the light input / output member 11 and the normal direction n2 of the light reflection surface of the input / output light reflecting mirror 12 are set to be non-parallel. Specifically, the angle between the light input / output surface of the light input / output member 11 and the light reflection surface of the input / output light reflecting mirror 12 is set to approximately 45 degrees. The folding mirror 13 has two reflecting surfaces 13A and 13B that are opened at substantially right angles. By setting the opening angle of the two reflecting surfaces 13A and 13B to approximately 90 degrees, the light beam is folded back in the direction parallel to the propagation direction of the incident light, so that the optical system can be easily designed. In the folding mirror 13, one reflecting surface 13 A faces the input light reflecting portion 12 A of the input / output light reflecting mirror 12 and the other reflecting surface 13 B of the input / output light reflecting mirror 12 is opposite to the input / output light reflecting mirror 12. It arrange | positions so that the output light reflection part 12B may be opposed.

  Accordingly, in FIG. 12, if the mirror surface of each micromirror element of the input / output light reflecting mirror 12 is parallel to the reflecting surface, for example, the light is input upward from the input position a of the light input portion 11A of the light input / output member 11. As shown by the optical path T <b> 1 in FIG. 12, the reflected light is reflected to the right by the mirror surface of the input / output light reflecting mirror 12 at a substantially right angle and is incident on the reflecting surface 13 </ b> A of the folding mirror 13. The light incident on the reflecting surface 13A is reflected upward at a substantially right angle and incident on the reflecting surface 13B. The light is reflected at the reflecting surface 13B in the left direction at a substantially right angle and is reflected on the output light reflecting portion 12B of the input / output light reflecting mirror 12. Incident. Then, the light is reflected downward at a substantially right angle by the output light reflecting portion 12B and output from the output position b of the light output portion 11B of the light input / output member 11.

  On the other hand, when the mirror surface of each micromirror element of the input / output light reflecting mirror 12 is tilted with respect to the reflecting surface, for example, as shown by the optical path T2 in FIG. The light incident from the input position a of the light input unit 11A is output from the output position b ′ of the light output unit 11B. That is, the output position in the light output unit 11B is switched from the output position b to the output position b '.

  In the optical switch 10, the spatial propagation distance of light in the optical switch 10 is increased by setting the mutual positional relationship of the light input / output member 11, the input / output light reflecting mirror 12 and the folding mirror 13 to the positional relationship shown in FIG. 12. The light input / output member 11, the input / output light reflecting mirror 12, and the folding mirror 13 are integrated into a compact configuration. In particular, by setting the angle formed by the light input / output surface of the light input / output member 11 and the light reflection surface of the input / output light reflection mirror 12 to approximately 45 degrees, each micromirror element of the input / output light reflection mirror 12 The length of the optical path between the input / output light reflecting mirror 12 and the folding mirror 13 with respect to the light deflection angle can be minimized.

  The arrangement direction of the collimator array of the light input / output member 11 (direction N1 in FIG. 12), the arrangement direction of the micro tilt mirror array of the input / output light reflection mirror 12 (direction N2 in FIG. 12), and the folding mirror 13 The optical path shift direction (direction N3 in FIG. 12) is parallel to a reference plane including the normal direction n2 of the input / output light reflecting mirror 12 and the propagation direction of light input from the light input / output member 11. You may do it. Alternatively, the directions N1 to N3 may be perpendicular to the reference plane. In this case, the spatial propagation distance of light in the optical switch 10 can be further shortened.

  Next, as another example of the optical switch, an optical switch for performing optical path switching for each wavelength can be cited. Such an optical switch (hereinafter referred to as “wavelength selective switch”) is, for example, a wavelength selector arranged in each node in a mesh network 15 for wavelength division multiplexing (WDM) communication shown in FIG. Provided in the switch module 17.

  The mesh network 15 includes a multiplexing unit 16, a wavelength selective switch module 17, and a demultiplexing unit 18. The multiplexing unit 16 combines a plurality of lights having different wavelengths transmitted through a plurality of different optical transmission paths (for example, optical fibers) and outputs the combined light to one optical transmission path. On the other hand, the demultiplexing unit 18 separates light of each wavelength from light including a plurality of different wavelengths transmitted through one optical transmission path, and outputs the light to each of the plurality of optical transmission paths. The wavelength selective switch module 17 functions as a cross bar switch for each wavelength.

  For example, as shown in FIG. 14, the wavelength selective switch module 17 includes a plurality of demultiplexing units 171 provided corresponding to the number of input ports (two in FIG. 14) connected to the input transmission path, and an output transmission path. Are provided between a plurality of multiplexing units 173 provided corresponding to the number of output ports (two in FIG. 14), and between the demultiplexing unit 171 and the multiplexing unit 173. And a plurality of 2 × 2 optical switches 172 that switch output destinations of a plurality of light beams separated for each output wavelength to a plurality of multiplexing units 173. The number n of 2 × 2 optical switches 172 corresponds to the number n of wavelengths that are split by the demultiplexing unit 171.

  In FIG. 14, the first demultiplexing unit 171 takes out light of each wavelength from light (WDM light) including n wavelengths input from the first input port P1, and n 2 × 2 optical switches. Input to 172 respectively. The second demultiplexing unit 171 takes out light of each wavelength from the WDM light including n wavelengths input from the second input port P2, and inputs the light to the n 2 × 2 optical switches 172, respectively.

  On the other hand, the first multiplexing unit 173 multiplexes a plurality of lights having different wavelengths respectively input from the n 2 × 2 optical switches 172, and outputs the multiplexed light from the first output port Q1 to the outside. The second multiplexing unit 173 multiplexes a plurality of lights having different wavelengths respectively input from the n 2 × 2 optical switches 172, and outputs the multiplexed light from the second output port Q2 to the outside.

  The 2 × 2 optical switch 172 performs output switching (cross output or bar output) to the two multiplexing units 173 of light having a predetermined wavelength respectively input from the two demultiplexing units 171.

  In the wavelength selective switch module 17, for example, WDM lights with wavelengths λ2, λ5, and λ6 are input to the first input port P1, and WDM lights with wavelengths λ1, λ3, λ4, and λ7 are input to the second input port P2. In this case, the first demultiplexing unit 171 splits the light into wavelengths λ2, λ5, and λ6, and the light of each wavelength is arranged in three 2 × 2 optical switches 172 corresponding to each wavelength (in FIG. When the 2 × 2 optical switch 172 is numbered from the top, it is input to the second, fifth and sixth 2 × 2 optical switches 172). In addition, the light is split into light of wavelengths λ1, λ3, λ4, and λ7 by the second demultiplexing unit 171, and the light of each wavelength is input to the first, third, fourth, and seventh 2 × 2 optical switches 172, respectively. Is done.

  In the first to seventh 2 × 2 optical switches 172, the output destinations of the light of each wavelength input based on the control signal are switched. In the example of FIG. 14, the second, fifth, and sixth 2 × 2 optical switches 172 output the light of wavelengths λ2 and λ5 to the second multiplexing unit 173, and the light of wavelength λ6 It is output to the wave unit 173. On the other hand, in each of the first, third, fourth, and seventh 2 × 2 optical switches 172, the light of wavelengths λ1 and λ4 is output to the first multiplexer 173, and the light of wavelengths λ3 and λ7 is the second The signal is output to the multiplexing unit 173. Accordingly, the first output port Q1 outputs the light multiplexed with the light having the wavelengths λ1, λ4, and λ6 by the first multiplexer 173, and the second output port Q2 outputs the second multiplexer 173. As a result, light multiplexed with wavelengths λ2, λ3, λ5, and λ7 is output.

  Note that the gain equalization function block shown in FIG. 14 includes, for example, the light to the core by appropriately shifting the condensing position on the output optical transmission line (optical fiber) in the 2 × 2 optical switch 172 from the core center. The amount of coupling is changed to adjust the gain of light of each wavelength.

  Next, a specific configuration of the wavelength selective switch module 17 will be described.

  FIG. 15 is a perspective view showing a basic configuration of the wavelength selective switch module 17. FIG. 16 is a cross-sectional view of a main part showing a spectroscope which is a component in the wavelength selective switch module 17, and FIG. 17 is a diagram schematically showing an array structure of micromirror elements in the micromirror array unit. .

  The wavelength selective switch module 17 is mounted on a substrate 1701, a collimator array 1702 constituting an optical system for inputting and outputting light, and a spectroscopic component constituting a spectroscopic optical system for dispersing input WDM light for each wavelength. 1703, a condensing lens 1704 constituting a condensing optical system, and a micromirror array unit 1705 which is an optical switching element.

  The collimator array 1702 forms, for example, a plurality (four in FIG. 15) of microlenses (collimator lenses, hereinafter simply referred to as “lenses”) arranged in a line on one surface of a glass substrate, and the other surface. A plurality of (four in FIG. 15) optical fibers 1702A and 1702B are connected to the respective lens portions by aligning the fiber center with the center of the lens and bonding or fusing. Some of the plurality of optical fibers are for light input, and the rest are for light output. In FIG. 15, two optical fibers 1702A in the upper two stages are for light input, and two optical fibers 1702B in the lower two stages are for light output.

  Accordingly, one of the optical fibers for optical input 1702A is connected to the upper branching unit 171 in FIG. 14, and the other of the optical fibers for optical input 1702A is connected to the lower branching unit 171 in FIG. Further, one of the optical fibers for optical output 1702B is connected to the upper combining unit 173 in FIG. 14, and the other of the optical fibers for optical output 1702B is connected to the lower combining unit 173 in FIG.

  The spectroscope 1703 reflects incident light in different directions (angles) depending on the wavelength. The spectroscope 1703 uses a diffraction grating. As shown in FIG. 16, the diffraction grating is an optical element in which a large number of parallel grooves 1703B are periodically engraved on a glass substrate 1703A. The diffraction grating reflects a plurality of wavelength components incident at a constant incident angle α by using a light diffraction phenomenon at an emission angle β different for each wavelength. As a result, the included wavelength of the incident WDM light is separated.

  Note that the diffraction grating shown in FIG. 16 is a phrase-type diffraction grating in which the groove 1703B is sawtoothed in order to increase diffraction efficiency. The diffraction grating shown in FIG. 16 is a reflection type, but a transmission type diffraction grating can also be used.

  The condensing lens 1704 condenses the light of each wavelength separated by the spectroscope 1703 onto a predetermined micromirror in the micromirror array unit 1705, and is reflected by any one of the micromirrors in the micromirror array unit 1705. The collected light is condensed on the spectroscope 1703.

  The micromirror array unit 1705 switches the reflection direction of the light collected by the spectroscope 1703. In the micromirror array unit 1705, as shown in FIG. 17, a plurality of micromirror elements constituted by the microstructure according to the present invention are arranged in a line at a predetermined interval P. FIG. 17 schematically shows the array structure of the micromirror elements, and the micromirror elements 1705B can be swung in each frame of a frame 1705A in which a plurality of frames are arranged in a line at a predetermined pitch. It is depicted as a configuration that supports it.

  The micromirror array unit 1705 switches the reflection direction of the light collected by the spectroscope 1703 as shown in FIG. 18 by changing the tilt angle of the mirror surface of each micromirror element 1705B. The correspondence relationship between the optical fiber for optical input 1702A and the two optical fibers for optical output 1702B is switched.

  In the example of FIG. 18, when light incident from the first optical fiber 1702A for light input passes through the spectroscope 1703 and the condenser lens 1704 and enters the micromirror array unit 1705 in the example of FIG. The light is reflected at a predetermined angle toward the optical path corresponding to the second optical fiber 1702B for light output. Accordingly, the reflected light from the micromirror array unit 1705 is guided to the second optical fiber 1702B for light output by the condenser lens 1704 and the spectroscope 1703, and is output from the second optical fiber 1702B.

  On the other hand, FIG. 6B shows the state in which the mirror surface of the micromirror array unit 1705 is tilted upward with respect to the state of FIG. The position where the light reflected by the micromirror array unit 1705 is condensed by the condenser lens 1704 moves to a position higher than that in the case of FIG. This corresponds to the optical fiber 1702B. Accordingly, the reflected light from the micromirror array unit 1705 is guided to the first optical fiber 1702B for light output by the condenser lens 1704 and the spectroscope 1703, and is output from the first optical fiber 1702B.

  The angle control of the mirror surface of each micromirror element in the micromirror array unit 1705 is performed by the control circuit to the drive circuit provided for each micromirror element as described in the angle control of the mirror surface 311 of the micromirror element 1. This is done by controlling the control signal.

  Since the light dispersed by the spectroscope 1703 is condensed on each mirror surface of the micromirror array unit 1705, the output optical fiber 1702B is controlled for each wavelength by controlling the inclination angle of each mirror surface. It will be switched.

  Further, by adjusting the inclination angle of each mirror surface of the micromirror array unit 1705, the condensing position of the optical fiber 1702B for output condensed through the condensing lens 1704 and the spectroscope 1703 changes. When this condensing position shifts from the core center of the output optical fiber 1702B, the amount of optical coupling changes. Therefore, the gain equalization function shown in FIG. 14 is realized by adjusting the inclination angle of each mirror surface of the micromirror array unit 1705.

  Next, as an application example of the microstructure according to the present invention, a vibration type angular velocity sensor using a Coriolis force and having a double gimbal structure will be described.

  An angular velocity sensor is a sensor for detecting a rotational angular velocity applied to an object. The angular velocity sensor is used for camera shake detection of a video camera, car navigation, roll angle detection for side air bag opening timing, attitude detection of a car or a robot, and the like.

  FIG. 19 is a top view showing a basic structure of an angular velocity sensor to which the microstructure according to the present invention is applied.

  The angular velocity sensor 20 includes a rectangular frame 21, a first gimbal portion 22 having a rectangular frame shape, and a first gimbal portion 22 having a rectangular frame shape. A second gimbal portion 23 having a rectangular shape supported so as to be swingable is provided.

  The first gimbal portion 22 has a recess formed at the center between a pair of opposing side surfaces 22a and 22c (upper and lower side surfaces in FIG. 19). Each concave portion of the first gimbal portion 22 is connected to the frame frame 21 by a torsion bar 24. Comb electrodes 221 and 222 are formed on the other pair of side surfaces 22b and 22d (left and right side surfaces in FIG. 19), respectively. On the other hand, a comb electrode 211 is formed on the side surface of the frame frame 21 that faces the side surface 22 b of the first gimbal portion 22 so that the comb teeth mesh with the comb teeth of the comb electrode 221. A comb-tooth electrode 212 is formed on the side surface of the frame frame 21 that faces the side surface 22 d of the first gimbal portion 22 so that the comb teeth mesh with the comb teeth of the comb-tooth electrode 222.

  The second gimbal portion 23 has a recess formed at the center between a pair of opposing side surfaces 23b and 23d (left and right side surfaces in FIG. 19). Each recess of the second gimbal part 23 is connected to the first gimbal part 22 by a torsion bar 25. Comb electrodes 231 and 232 are respectively formed on another pair of opposing side surfaces 23a and 23c (upper and lower side surfaces in FIG. 19). On the other hand, on the inner side surface of the first gimbal portion 23 that faces the side surface 23a of the second gimbal portion 23, a comb tooth electrode 223 is formed so that the comb teeth mesh with the comb teeth of the comb tooth electrode 231. . A comb-tooth electrode 224 is formed on the inner side surface of the first gimbal portion 22 that faces the side surface 22 c of the second gimbal portion 23 so that the comb teeth mesh with the comb teeth of the comb-tooth electrode 232.

  In FIG. 19, the torsion bars 24 and 25 are drawn with a single bar, but the torsion bars 24 and 25 are a pair of V-shaped bars as in the torsion bar 4 shown in FIG. Consists of.

  As shown in FIG. 20, the angular velocity sensor 20 has a comb-teeth electrode when the axial direction of the torsion bar 25 is the X axis, the axial direction of the torsion bar 24 is the Y axis, and the direction perpendicular to the X axis and the Y axis is the Z axis. The first gimbal portion 22 is moved in the Y-axis direction by alternately applying a drive voltage between 211 and the comb electrode 221 and applying a drive voltage between the comb electrode 212 and the comb electrode 222. Vibrating around the center. At this time, the second gimbal portion 23 vibrates around the Y axis integrally with the first gimbal portion 22 unless the rotational force around the X axis acts. That is, the second gimbal part 23 (hereinafter referred to as “detection gimbal part 23”) does not tilt with respect to the first gimbal part 22 (hereinafter referred to as “drive gimbal part 22”).

  In this state, when a rotational angular velocity Ωz is applied around the Z axis, a Coriolis force is generated in a direction perpendicular to the Y axis, and this Coriolis force acts on the detection gimbal portion 23 as a rotational force around the X axis, thereby detecting the gimbal. The part 23 vibrates around the X axis. Note that the drive gimbal portion 22 cannot rotate around the X axis, and therefore does not swing due to the Coriolis force. Due to the vibration around the X axis of the detection gimbal portion 23, the capacitance between the comb electrode 231 and the comb electrode 223 (or the potential between the electrodes), the comb electrode 232 and the comb electrode 224 The capacitance between them (or the potential between the electrodes) changes. The amplitude of vibration of the detection gimbal portion 23, that is, the displacement angle θx around the X axis is proportional to the change width of the capacitance (or the potential between the electrodes) and proportional to the Coriolis force. The change width of the potential between them is proportional to the displacement angle θx. Therefore, the rotational angular velocity Ωz is detected by detecting the change width of the capacitance or the change width of the potential between the electrodes.

  Also in the angular velocity sensor 20, the position and shape of the torsion bars 24, 25 in the height direction affect the vibration characteristics of the drive gimbal part 22 and the detection gimbal part 23 as in the case of the micromirror element 1. Therefore, when the angular velocity sensor 20 is manufactured by the bulk micromachining technique using the SOI substrate, the torsion bars 24 and 25 are disposed at positions where the torsion bars 24 and 25 below the torsion bars 24 and 25 do not interfere with the twisting operation. By forming the structures 5 and 5 ′ that give the reference surface Sr for position measurement, the positions of the torsion bars 24 and 25 can be accurately measured.

  As described above, the present invention can be widely applied to a microstructure having a structure in which an SOI substrate is processed by bulk micromachining technology and a swing member is supported swingably on a frame via a torsion bar. . Therefore, the present invention is not limited to the micromirror element and the angular velocity sensor disclosed as the above embodiment, and can be applied to other vibration elements such as an acceleration sensor.

  In the above embodiment, the case where an SOI substrate in which two silicon layers are stacked with one insulating layer interposed therebetween is used, but the stacked structure of the SOI substrate is not limited to this, and a plurality of insulating layers is used. And a structure in which a plurality of conductor layers are alternately laminated.

  Regarding the above embodiment, the following additional notes are disclosed.

(Appendix 1)
A frame-shaped fixing portion and a swinging portion supported in a swingable manner by a pair of torsion bars in the fixing portion, and an SOI substrate formed by laminating two conductor layers with an insulating layer interposed therebetween, In the microstructure manufactured by processing to form the swinging portion, the pair of torsion bars are formed at a position that is in contact with the insulating layer of one conductor layer with a thickness thinner than the conductor layer, A micro structure in which a structure having the same thickness as the conductor layer is provided in a portion that is located below each torsion bar of the conductor layer and does not interfere with the twisting operation of the torsion bar.

(Appendix 2)
The microstructure according to appendix 1, wherein a surface of the structure facing the torsion bar is a reference surface at a position in the thickness direction of the one conductor layer of the torsion bar.

(Appendix 3)
The microstructure according to appendix 1 or 2, wherein the structure is formed on the other conductor layer of both the fixed portion and the swinging portion.

(Appendix 4)
The microstructure according to appendix 1 or 2, wherein the structure is formed on the other conductor layer of either the fixed portion or the swinging portion.

(Appendix 5)
The torsion bar includes a plurality of rod-shaped bodies connected between the fixing portion and the swinging portion, and the structure includes the fixing portion, the swinging portion, and the plurality of the other conductor layers. In the appendix 1 or 2, the cross-sectional shape along the layer of the conductor layer of the structure, which is provided on the lower side of the space shape formed by the rod-shaped body, is substantially the same shape as the space shape. The described microstructure.

(Appendix 6)
The structure includes a first structure provided on a lower portion of a space shape formed by the fixed portion, the swinging portion, and the plurality of rod-shaped bodies of the other conductor layer, and the other conductor layer. A second structure body provided at a portion outside the position facing the plurality of rod-shaped bodies of the conductor layer, and the cross-sectional shape along the layer of the conductor layer of the first structure body has the space Additional shape 1 or 2 which is substantially the same shape as the shape, and the cross-sectional shape along the conductor layer of the second structure is a horizontally long rectangular shape having long sides along the plurality of rod-shaped bodies. The microstructure according to 1.

(Appendix 7)
The microstructure according to appendix 5 or 6, wherein the torsion bar is a V-shaped member having a V-shaped open side connected to the swinging portion and a V-shaped narrowed side connected to the fixed portion. body.

(Appendix 8)
The micro structure according to appendix 7, wherein a cross-sectional shape of a structure provided in a lower portion of the space shape is substantially the same triangular shape as a triangle surrounded by the torsion bar and the swinging portion. body.

(Appendix 9)
9. The microstructure according to any one of appendices 1 to 8, wherein the structure has a cylindrical shape opened on a surface of the other conductor layer that is not in contact with the insulator.

(Appendix 10)
The microstructure according to appendix 9, wherein the structure is formed into a cylindrical shape by a two-stage etching process.

(Appendix 11)
A microelement comprising the microstructure according to any one of appendices 1 to 10.

(Appendix 12)
The microelement according to appendix 11, including at least a mirror element, an angular velocity sensor, and an acceleration sensor.

It is a perspective view which shows the micromirror element which concerns on this invention. It is a perspective view which shows the part of the structure provided in the micromirror element. The structure provided in the micromirror element is shown, (a) is a view seen from above, (b) is a sectional view taken along line III-III in FIG. It is a figure showing the one part process in the manufacturing method of the micromirror element which concerns on this invention. It is a figure showing the remaining processes following FIG. It is a figure which shows the measuring method of the position of a torsion bar. It is a figure which shows the 1st modification of a structure. It is a figure which shows the 2nd modification of a structure. It is a perspective view which shows the 3rd modification of a structure. It is a perspective view which shows the part of the structure of the micromirror element which concerns on 2nd Embodiment. It is a figure which shows the basic composition of the optical switch using the micro tilt mirror array comprised with the microstructure which concerns on this invention. It is a top view which shows the basic composition of the optical switch. It is a figure which shows the basic composition of a mesh type network. It is a figure which shows the internal structure of a wavelength selection switch module. It is a perspective view which shows the basic composition of a wavelength selection switch module. It is principal part sectional drawing of a spectrometer. It is the figure which showed typically the array structure of the micromirror element in a micromirror array unit. It is a figure for demonstrating the optical switch function in a micromirror array unit. It is a figure which shows the basic structure of the angular velocity sensor comprised with the microstructure which concerns on this invention. It is a perspective view for demonstrating the principle of operation of an angular velocity sensor. It is a perspective view which shows the conventional micromirror element. It is a perspective view which shows the part of the torsion bar of the conventional micromirror element. It is AA sectional view taken on the line of FIG. It is a perspective view which shows the structure of a dummy torsion bar.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Micromirror element 2 Frame 21 Comb electrode 3 Oscillating member 31 Mirror part 32 Oscillating shaft 33 Comb electrode 4, 4 'Torsion bar 5, 5' Structure 6 SOI substrate 61 1st silicon layer (conductor layer)
62 Second silicon layer (conductor layer)
63 Insulating film (BOX layer)
64, 66 Oxide film pattern 65 Resist pattern 7 Drive circuit 8 Control circuit 9 Second structure 10 Optical switch 11 Optical input / output member 12 Input / output light reflecting mirror 13 Folding mirror 15 Mesh type network 16 Multiplexing unit 17 Wavelength selection switch Module 171 Demultiplexing unit 172 2 × 2 optical switch 1701 Substrate 1702 Collimator array 1703 Spectrometer 1704 Condensing lens 1705 Micro mirror array unit 173 Multiplexing unit 18 Demultiplexing unit 20 Angular velocity sensor 21 Frame frame 211, 212 Comb electrode 22 Second 1 gimbal part 221, 222, 223, 224 comb tooth electrode 23 second gimbal part 231, 232 comb tooth electrode 24, 25 torsion bar

Claims (9)

A frame-shaped fixing portion and a swinging portion supported in a swingable manner by a pair of torsion bars in the fixing portion, and the fixing portion and the swinging motion on an SOI substrate in which two conductor layers are stacked with an insulating layer interposed therebetween In the microstructure manufactured by applying the processing to form the part,
The pair of torsion bars is formed with a thickness thinner than the conductor layer at a position in contact with the insulating layer of one conductor layer,
A structure having the same thickness as that of the conductor layer is provided on each of the other conductor layers on the lower side of each torsion bar and does not interfere with the twisting operation of the torsion bar .
A microstructure having a surface facing the torsion bar of the structure as a reference surface for measuring a distance to an upper surface of the torsion bar . A frame-shaped fixing portion and a swinging portion supported in a swingable manner by a pair of torsion bars in the fixing portion, and the fixing portion and the swinging motion on an SOI substrate in which two conductor layers are stacked with an insulating layer interposed therebetween In the manufacturing method of the microstructure manufactured by applying the processing to form the part,
Forming the pair of torsion bars at a position in contact with the insulating layer of one conductor layer with a thickness thinner than the conductor layer;
A step of forming a structure having the same thickness as the conductor layer in a portion that is located below each torsion bar of the other conductor layer and does not interfere with the twisting operation of the torsion bar;
Measuring the distance to the top surface of the torsion bar using the surface facing the torsion bar of the structure as a reference plane;
The manufacturing method of the microstructure containing this . The structure, wherein both the fixed portion and the oscillating portion is formed on the other conductor layer, according to claim 1 micro structure according. The microstructure according to claim 1 , wherein the structure is formed on the other conductor layer of either the fixed portion or the swinging portion. The torsion bar includes a plurality of rod-shaped bodies connected between the fixed portion and the swinging portion,
The structure is provided on a lower portion of a space shape formed by the fixed portion, the swinging portion, and the plurality of rod-shaped bodies of the other conductor layer, and the layer of the conductor layer of the structure sectional shape along, said a spatial shape and substantially the same shape, micro structure according to claim 1. The structure includes a first structure provided on a lower portion of a space shape formed by the fixed portion, the swinging portion, and the plurality of rod-shaped bodies of the other conductor layer, and the other conductor layer. A second structure provided at a portion outside the position facing the plurality of rod-shaped bodies of the conductor layer,
The cross-sectional shape along the conductor layer layer of the first structure is substantially the same shape as the space shape, and the cross-sectional shape along the conductor layer layer of the second structure is The microstructure according to claim 1 , which is a horizontally long rectangular shape having long sides along a plurality of rod-like bodies. The microstructure according to claim 1 , wherein the structure has a cylindrical shape that is open on a surface of the other conductor layer that is not in contact with the insulator.   The microstructure according to claim 5, wherein the structure is formed in a cylindrical shape by a two-stage etching process. A microelement comprising the microstructure according to any one of claims 1 and 3 to 8.

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