JP6064839B2 - MEMS equipment - Google Patents

Description

  The present specification relates to a MEMS (Micro Electro Mechanical Systems) apparatus.

  2. Description of the Related Art A MEMS device including a substrate and a movable portion that can be tilted relative to the substrate is known. Such a MEMS device is applied as an optical deflection device, for example. In this type of optical deflection apparatus, the mirror is fixed to the movable part, and the angle of the mirror is adjusted by tilting the movable part with respect to the substrate.

  For example, in a MEMS device used as an optical deflecting device, the movable part preferably has characteristics such as high mechanical reliability, and the mirror preferably has characteristics such as high reflectance. Since the required characteristics are different from each other, it is preferable that the movable portion and the mirror are formed of different materials and fixed to each other according to the required characteristics. Patent Document 1 describes a MEMS device in which a semiconductor substrate, an inorganic film, and an organic film are stacked in this order. Here, the organic film extends to the semiconductor substrate through the penetrating portion of the inorganic film, and has a locking portion that protrudes in the planar direction from the penetrating portion so as to be locked to the surface of the inorganic film on the semiconductor substrate side. ing.

JP 2004-130442 A

  In Patent Document 1, when the MEMS device is exposed to a high temperature or the like, a large thermal stress is generated in the inorganic film or the semiconductor substrate due to expansion of the portion that passes through the through portion of the organic film or the locking portion. This stress generation may cause a characteristic variation of the MEMS device or a breakdown.

  A MEMS device disclosed in the present specification includes a substrate, a movable portion that is disposed above the substrate and can be tilted relative to the substrate, and a support beam that tiltably supports the movable portion with respect to the substrate, A light reflecting film disposed above the movable part; a support that connects the movable part and the light reflecting film apart in the vertical direction; and a torque generation mechanism that generates torque for tilting the movable part. . In this MEMS device, the movable part has a through-hole penetrating from the upper surface to the lower surface. The support column penetrates the through-hole in the vertical direction, protrudes laterally from the through-hole along the lower surface of the movable part and is locked to the movable part, and is hollow at least in a part penetrating the through-hole. .

  In the MEMS device described above, the support column penetrates the through hole in the vertical direction and protrudes in the lateral direction from the through hole on the lower surface of the movable part to be locked to the movable part. For this reason, a light reflection film and a movable part can be reliably fixed via a support | pillar. Furthermore, the support column is hollow at least in a portion passing through the through hole. For this reason, even when the column expands when the MEMS device is exposed to a high temperature or the like, the thermal stress is relaxed by the hollow portion, and generation of a large thermal stress in the MEMS device can be suppressed. According to the MEMS device described above, it is possible to achieve both the fixing of the light reflecting film and the movable portion with certainty and the suppression of the occurrence of thermal stress that can cause the characteristic variation of the MEMS device and the destruction.

  The light reflecting film may be flat above the support column. Since the upper part of the support pillar is not opened and the light reflecting film positioned above the support pillar is flat, the ratio (opening ratio) of the light reflecting film per plane area of the MEMS device can be improved.

  The torque generating mechanism may have a fixed electrode formed on the substrate, and the movable part may have a movable electrode. In this case, it is preferable that the support column is disposed at a position not vertically above the fixed electrode. Accordingly, the movable electrode of the movable part can be disposed at a position vertically above the fixed electrode, and the movable part can be efficiently tilted by the torque generation mechanism.

  In the MEMS device described above, the support column may protrude laterally from the through hole on the upper surface side of the movable part. Since the support is also locked to the upper surface of the movable part, the light reflecting film and the movable part can be more reliably fixed via the support.

  According to the technology disclosed in the present specification, it is possible to achieve both the fixing of the light reflecting film and the movable part surely and the suppression of the occurrence of thermal stress that may cause the characteristic variation of the MEMS device and the breakdown. .

1 is a perspective view showing a configuration of an optical deflecting device 10. FIG. FIG. 2 is a cross-sectional view of the light deflection apparatus 10 taken along the line II-II. 2 is a perspective view showing a configuration of a part of the light deflection apparatus 10. FIG. FIG. 5 is a diagram illustrating a method for manufacturing the optical deflection apparatus 10. FIG. 5 is a diagram illustrating a method for manufacturing the optical deflection apparatus 10. FIG. 5 is a diagram illustrating a method for manufacturing the optical deflection apparatus 10. FIG. 5 is a diagram illustrating a method for manufacturing the optical deflection apparatus 10. FIG. 5 is a diagram illustrating a method for manufacturing the optical deflection apparatus 10. FIG. 5 is a diagram illustrating a method for manufacturing the optical deflection apparatus 10. FIG. 5 is a diagram illustrating a method for manufacturing the optical deflection apparatus 10. FIG. 3 is a cross-sectional view of the light deflection apparatus 20. FIG. 3 is a perspective view showing a configuration of a part of the light deflection apparatus 20. FIG. 10 is a diagram illustrating a method for manufacturing the optical deflection apparatus 20. FIG. 10 is a diagram illustrating a method for manufacturing the optical deflection apparatus 20. FIG. 10 is a diagram illustrating a method for manufacturing the optical deflection apparatus 20. FIG. 10 is a diagram illustrating a method for manufacturing the optical deflection apparatus 20. FIG. 10 is a diagram illustrating a method for manufacturing the optical deflection apparatus 20. FIG. 10 is a diagram illustrating a method for manufacturing the optical deflection apparatus 20. FIG. 10 is a diagram illustrating a method for manufacturing the optical deflection apparatus 20.

  Hereinafter, an optical deflecting device 10 that is a MEMS device according to an embodiment will be described with reference to FIGS. The light deflection apparatus 10 includes a lower substrate 101, an upper substrate 102, a movable portion 121, support beams 123a and 123b, a light reflecting film 131, a support 140, and a torque generation mechanism. Although not shown, the movable part 121 has a movable electrode inside. Fixed electrodes 105 a and 105 b are disposed on the upper surface of the upper substrate 102. The movable electrode and the fixed electrodes 105a and 105b are part of the torque generation mechanism.

  The upper substrate 102 is laminated on the upper surface (surface in the positive z-axis direction) of the lower substrate 101. The upper substrate 102 has a quadrangular frame 113 having four sides in the x direction and the y direction on the upper surface thereof. The frame 113 has circular portions 113a and 113b arranged symmetrically with respect to the x axis at the center position in the x direction. The circular portions 113 a and 113 b protrude in a substantially semicircular shape toward the center of the frame 113. The upper substrate 102 further has cylindrical portions 125a and 125b extending upward (in the positive z-axis direction) from the circular portions 113a and 113b. The cylindrical portions 125a and 125b are joined to the upper surfaces of the circular portions 113a and 113b on the lower surfaces thereof, and are joined to the lower surfaces of the support beams 123a and 123b on the upper surfaces thereof.

  The movable portion 121 has a substantially H shape that is symmetric with respect to the x-axis and the y-axis, and has a through-hole 126 that penetrates vertically in a substantially square shape at the center position in the x-direction and y-direction. ing. The support beams 123 a and 123 b extend from the cylindrical portions 125 a and 125 b toward the center of the movable portion 121 along the y-axis direction, and are connected to the movable portion 121. The support beams 123a and 123b have the same shape and are arranged at positions symmetrical to each other with respect to the x axis. The movable portion 121 is supported by support beams 123a and 123b so as to be tiltable about a tilt axis parallel to the y-axis. The fixed electrodes 105a and 105b are disposed below the movable portion 121 at positions that are symmetrical with respect to the tilt axis. By applying a potential to the fixed electrodes 105a and 105b and the movable electrode so that an electrostatic attractive force is generated between any one of the fixed electrodes 105a and 105b and the movable electrode, the substrate (the lower substrate 101 and the upper substrate 102). ) With respect to the movable portion 121.

  The upper surface of the light reflecting film 131 is a mirror and can reflect light. A column 140 is bonded to the lower surface of the light reflecting film 131. As shown in FIG. 3, the column 140 has an upper portion 141 and a lower portion 142 each having a substantially prismatic shape. As shown in FIG. 2, in the support column 140, the lower end portion of the upper portion 141 passes through the through hole 126 of the movable portion 121, and the lower portion 142 is laterally extended along the lower surface of the movable portion 121 (x direction and y direction). Formed in a protruding state. As shown in FIG. 2, the width of the through-hole 126 in the x direction and the y direction is D1 (only the width in the y direction is shown in FIG. 2, but the width in the x direction is also D1). The width of the part is D2 (in FIG. 2, only the width in the y direction is shown, but the width in the x direction is also D2). The width in the x direction and the y direction of the lower end portion of the upper portion 141 that penetrates the through hole 126 is also substantially equal to D1. The width D2 is larger than the width D1 (D2> D1). Further, the width of the upper portion 141 is narrowest at the portion passing through the through hole 126. That is, the upper portion 141 protrudes laterally from the through hole 126 also on the upper surface side of the movable portion 121.

  The support column 140 penetrates the through hole 126 in the vertical direction and protrudes laterally from the through hole 126 along the lower surface of the movable portion 126 so as to be locked to the movable portion 121, thereby allowing the light reflecting film to pass through the support column 140. 131 and the movable part 121 are fixed. The light reflecting film 131 is connected to the upper part of the movable part 121 so as to be separated from the movable part 121 via the support column 140. The light reflecting film 131 can be tilted with respect to the substrates (the lower substrate 101 and the upper substrate 102) by tilting the movable portion 121 around the tilt axis by the torque generation mechanism. The support column 140 has a hollow 143. The hollow 143 extends from above the portion of the upper portion 141 penetrating the through hole 126 to the lower end of the lower portion 142. The support 140 is open at the bottom. The upper surface of the support 140 is a flat surface and is bonded to the lower surface of the light reflecting film 131. The light reflecting film 131 is flat above the support 140. Moreover, the support | pillar 140 is arrange | positioned in the position which does not become the perpendicular | vertical upper direction of fixed electrode 105a, 105b.

  As described above, in the optical deflecting device 10, the support column 140 penetrates the through hole 126 in the vertical direction and protrudes laterally from the through hole 126 on the lower surface of the movable portion 121 and is locked to the movable portion 121. For this reason, the light reflecting film 131 and the movable part 121 can be reliably fixed via the support column 140. Further, the support column 140 has a hollow 143 at least in a portion that passes through the through hole 126. For this reason, even when the optical deflecting device 10 is exposed to a high temperature or the like, even if the support column 140 expands, the thermal stress is relieved by deformation toward the hollow 143, and the optical deflecting device 10 is greatly affected. Generation of thermal stress can be suppressed. According to the optical deflecting device 10, both the light reflecting film 131 and the movable portion 121 are securely fixed and the characteristic variation of the optical deflecting device 10 and the generation of thermal stress that can cause destruction are both achieved. it can.

  Further, in the optical deflecting device 10, the support column 140 protrudes laterally from the through hole 126 on the upper surface side of the movable portion 121. Since the support 140 is also locked to the upper surface of the movable portion 121, the light reflecting film 131 and the movable portion 121 can be more reliably fixed via the support 140.

  Further, in the optical deflecting device 10, the lower portion 142 of the column 140 protrudes downward from the lower surface of the movable portion 121. For this reason, when the optical deflecting device 10 vibrates and the movable part 121 sinks downward, the support column 140 comes into contact with the lower structure of the upper substrate 102, the fixed electrodes 105a and 105b, etc., thereby preventing sticking. it can.

  Further, in the light deflecting device 10, the support 140 has a flat light reflection film 131 positioned above the support 140 without opening up the support 140. For this reason, the ratio (aperture ratio) of the light reflection film 131 per area of the light deflection apparatus 10 can be improved.

  Further, in the optical deflecting device 10, the support column 140 is disposed at a position that is not vertically above the fixed electrodes 105a and 105b. For this reason, the movable electrode of the movable portion 121 can be disposed at a position vertically above the fixed electrodes 105a and 105b, and the movable portion 121 can be efficiently tilted by the torque generation mechanism.

  A method for manufacturing the optical deflection apparatus 10 will be described. Since the optical deflecting device 10 can be manufactured using techniques such as sputtering, pattern etching, and CVD, which are generally used in the manufacture of semiconductors, a detailed description of specific procedures such as pattern etching and CVD is as follows. Omitted.

First, as shown in FIG. 4, a substrate 40 is prepared. The substrate 40 is an SOI substrate, and includes a handle layer 490 made of Si, a Box layer 480 made of SiO ₂ and an active layer 420 made of Si, which are stacked in this order.

  Next, as shown in FIG. 5, anisotropic etching is performed to pattern the active layer 420 according to the shape of the movable portion 121. The active layer 420 is a layer that becomes the movable portion 121, and the hole 426 is a hole that becomes the through hole 126. Further, isotropic etching is performed on the Box layer 480 to form a hole 486. The hole 486 is larger in the x and y directions than the hole 426. As will be described later, the upper portion 141 of the column 140 is formed using the hole 486 as a mold. The hole 486 is designed according to the shape of the upper portion 141.

  Next, as shown in FIG. 6, an Al (aluminum) layer 440 is formed on the inner wall surfaces of the holes 426 and 486 and the active layer 420 around the holes 426. The Al layer 440 can be formed by forming an aluminum film on the substrate 40 shown in FIG. 5 and then removing the aluminum film leaving the inner wall surfaces of the holes 426 and 486 and the periphery of the holes 426. The aluminum film can be formed by sputtering or the like. The Al layer 440 is a layer that becomes the support column 140 and is patterned along its shape. The Al layer 440 is made hollow by adjusting the size of the holes 426 and 486 (that is, the size of the support column 140 and the through hole 126) and the thickness of the aluminum film formed on the substrate 40. Can do. In addition, since the Al layer 440 serving as the support column 140 is formed using the holes 426 and 486 as a mold, the movable portion 121 and the support column 140 can be securely fixed.

  Next, as shown in FIG. 7, a pair of cylinders 425 a and 425 b are joined to part of the active layer 420. The cylinders 425a and 425b are made of aluminum and become cylinder parts 125a and 125b.

  Next, as shown in FIG. 8, the substrate 40 is turned upside down and bonded onto the substrate 42. The substrate 42 includes a substrate layer 401 made of Si (becomes the lower substrate 101), a substrate layer 402 made of Si (being part of the upper substrate 102), and a circular portion 413a made of aluminum. A frame including 413b (circular portions 113a and 113b) (becomes the frame 113) and a pair of electrodes (becomes fixed electrodes 105a and 105b) are included. The frame and the electrode can be formed by forming an aluminum film on the upper surface of the substrate layer 402 and then patterning the aluminum film. The lower surfaces (surfaces in the negative direction of the z axis) of the cylinders 425a and 425b are joined to the upper surfaces (surfaces in the positive direction of the z axis) of the circular portions 413a and 413b, respectively.

  Next, as shown in FIG. 9, the handle layer 490 is removed by etching or the like, and the light reflecting film 430 made of aluminum as a material is formed on the upper surfaces (surfaces in the positive z-axis direction) of the Box layer 480 and the Al layer 440. A light reflecting film 131). Since both the Al layer 440 and the light reflection film 430 are made of aluminum, the support column 140 and the light reflection film 131 can be reliably bonded.

  Next, as shown in FIG. 10, the Box layer 480 is removed by etching. Thereby, the optical deflection apparatus 10 can be manufactured.

  FIG. 11 shows an optical deflecting device 20 according to the second embodiment. As shown in FIGS. 11 and 12, the optical deflecting device 20 is different from the optical deflecting device 10 in the shapes of the support column 240 and the light reflecting film 231.

  Each support column 240 has a substantially prismatic upper portion 241 and a lower portion 242. As shown in FIG. 11, the support column 240 is inserted so that the lower end portion of the upper portion 241 penetrates the through hole 226 of the movable portion 221, and the lower portion 242 extends in the lateral direction (x direction) along the lower surface of the movable portion 221. And y direction). As shown in FIG. 11, the width of the through hole 226 in the x direction and the y direction is D1 (only the width in the y direction is shown in FIG. 11, but the width in the x direction is also D1), and the lower end of the lower portion 241 The width of the part is D2 (in FIG. 11, only the width in the y direction is shown, but the width in the x direction is also D2). The widths in the lower end x direction and the y direction of the upper part 241 that penetrates the through hole 226 are also substantially equal to D1. The width D2 is larger than the width D1 (D2> D1). Further, the width of the upper portion 241 is narrowest at the portion passing through the through hole 226. That is, the upper part 241 protrudes in the lateral direction from the through hole 226 also on the upper surface side of the movable part 221. The support column 240 passes through the through-hole 226 in the vertical direction and protrudes laterally from the through-hole 226 along the lower surface of the movable portion 226 so as to be locked to the movable portion 221. 231 and the movable part 221 are fixed. The light reflecting film 231 is connected to the upper part of the movable part 221 so as to be separated from the movable part 221 via the support column 240. The support column 240 is a closed surface with a flat bottom surface, and the top surface is open. The support column 240 has a hollow 243. The hollow 243 extends from the side of the lower part 242 close to the movable part 221 to the upper end of the upper part 241. The mirror surface of the light reflecting film 231 is opened above the support column 240. Since the other configuration of the optical deflecting device 20 is the same as that of the optical deflecting device 10, the description thereof is omitted by replacing the reference numbers in the 100s of the optical deflecting device 10 with the 200s. Similarly to the optical deflection apparatus 10, the optical deflection apparatus 20 includes a torque generation mechanism such as fixed electrodes 105a and 105b.

  Similarly to the optical deflection apparatus 10, the optical deflection apparatus 20 also securely fixes the light reflecting film 231 and the movable portion 221, generates fluctuations in characteristics of the optical deflection apparatus 20, and generates thermal stress that can cause destruction. It is possible to obtain an effect such as achieving both suppression.

  A method for manufacturing the optical deflector 20 will be described. As in the first embodiment, the optical deflecting device 20 omits a detailed description of a specific procedure such as pattern etching generally used in semiconductor manufacturing.

First, as shown in FIG. 13, a substrate 50 is prepared. The substrate 50 is an SOI substrate, and includes a handle layer 590 made of Si, a Box layer 580 made of SiO ₂ , and an active layer 520 made of Si, which are stacked in this order.

  Next, as shown in FIG. 14, anisotropic etching is performed to pattern the active layer 520 according to the shape of the movable portion 221. However, a hole to be the through hole 226 is not formed at this stage.

Next, an insulating layer 582 made of SiO ₂ is formed by CVD or the like on the upper surface (surface in the negative z-axis direction) of the substrate 520 shown in FIG. Next, the insulating layer 582 is pattern-etched to form holes, and the holes in the insulating layer 582 are filled with aluminum to form the cylinders 525a and 525b. The holes of the insulating layer 582 are designed according to the outer shape of the cylinders 225a and 225b, and the cylinders 525a and 525b become the cylinders 225a and 225b of the light deflector 20.

  Next, as shown in FIG. 16, the substrate 50 is turned upside down and bonded onto the substrate 52. The substrate 52 includes a substrate layer 501 made of Si (becomes the lower substrate 201), a substrate layer 502 made of Si (becomes a part of the upper substrate 202), and a circular portion 513a made of aluminum. A frame including 513b (becomes circular portions 213a and 213b) and a pair of electrodes (becomes fixed electrodes) are included. The frame and the electrode can be formed by forming an aluminum film on the surface of the substrate layer 502 and then patterning the aluminum film. The lower surfaces (surfaces in the negative direction of the z axis) of the cylinders 525a and 525b are joined to the upper surfaces (surfaces in the positive direction of the z axis) of the circular portions 513a and 513b, respectively.

  Next, as shown in FIG. 17, the handle layer 590 is removed by etching or the like. Next, isotropic etching of the Box layer 580, anisotropic etching of the active layer 520, and isotropic etching of the insulating layer 582 are performed to form the holes 586. As will be described later, the support column 240 is formed using the hole 586 as a mold. The hole 586 is designed according to the shape and size of the column 240. The shape and size of the hole 586 in the active layer 520 are designed according to the shape and size of the through hole 226.

  Next, as shown in FIG. 18, an Al layer 530 made of aluminum is formed along the upper surface of the Box layer 580 and the inner wall surface of the hole 586. In the Al layer 530, a portion 540 formed along the wall surface of the hole 586 becomes the support column 240, and a portion formed on the upper surface of the Box layer 580 becomes the light reflecting film 231. By adjusting the size of the hole 586 (that is, the size of the support column 240 and the through hole 226) and the thickness of the Al layer 530, the Al layer 540 can be made hollow. Since the support column 240 and the light reflection film 231 are integrally formed as the Al layer 530, the support column 240 and the light reflection film 231 can be securely fixed. Moreover, since the part 540 used as the support | pillar 240 is formed using the hole 586 as a type | mold, the movable part 221 and the support | pillar 240 can be fixed reliably.

  Next, as shown in FIG. 19, the Box layer 580 and the insulating layer 582 are removed by etching. Thereby, the light deflection apparatus 20 can be manufactured.

  As mentioned above, although the Example of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

10, 20: Optical deflecting device 101, 201: Lower substrate 102, 202: Upper substrate 105a, 105b: Fixed electrodes 121, 221: Movable parts 123a, 123b, 223a, 223b: Support beams 126, 226: Through holes 131, 231 : Light reflecting film 140, 240: Support

Claims (4)

A substrate,
A movable part disposed above the substrate and capable of tilting relative to the substrate;
A support beam for tilting the movable part relative to the substrate;
A light reflecting film disposed above the movable part;
A strut that connects the movable part and the light reflecting film apart in the vertical direction;
A torque generating mechanism that generates torque for tilting the movable part,
The movable part has a through-hole penetrating from the upper surface to the lower surface,
The support column penetrates the through-hole in the vertical direction, protrudes laterally from the through-hole along the lower surface of the movable part and is locked to the movable part, and is hollow at least in a part penetrating the through-hole. MEMS device.   The MEMS device according to claim 1, wherein the light reflecting film is flat above the support column. The torque generating mechanism has a fixed electrode formed on the substrate,
The movable part has a movable electrode,
The MEMS device according to claim 1, wherein the support column is disposed at a position not vertically above the fixed electrode.   The MEMS device according to any one of claims 1 to 3, wherein the support column protrudes laterally from the through hole on the upper surface side of the movable portion.

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