Semiconductor device and method for manufacturing the same

Abstract

To provide a semiconductor device with an accurate structure provided in a cavity SOI wafter.SOLUTION: The semiconductor device includes: a fixation member having a first wafer and a second wafer connected to the first wafer; and a function unit formed on the fixation member, for realizing a predetermined function. The first wafer has a supporting layer and an active layer on the supporting layer. The active layer has a first hollow part and a second hollow part for connecting the first hollow part and the outside of the fixation member together.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to semiconductor devices and methods for manufacturing semiconductor devices. [Background technology]

[0002] In recent years, with the advancement of micromachining technology that applies semiconductor manufacturing technology, MEMS (Micro Electro Mechanical Systems) devices manufactured by microfabricating silicon or glass have been developed. A known MEMS device is an optical deflection element in which a movable part with a reflective surface and an elastic beam are integrally formed on a wafer, and the movable part is driven (rotated) by a driving beam made by overlaying a thin-film piezoelectric material on the elastic beam.

[0003] Wafers used in MEMS devices include SOI (Silicon On Insulator) wafers made of silicon and glass, as well as cavity SOI wafers, which are made by bonding a pre-patterned wafer to another wafer to create a hollow structure.

[0004] Patent Document 1 discloses a technique for improving the degree of vacuum inside the cavity by forming a gas exhaust path around the cavity and exhausting the gas inside the cavity by heat treatment after bonding. Summary of the Invention [Problem to be solved by the invention]

[0005] However, in MEMS devices fabricated using conventional semiconductor processing technology on cavity SOI wafers, the surface of the wafer containing the cavity can expand or collapse due to the pressure of the surrounding environment. Such changes in the wafer surface are caused by a pressure difference between the pressure in the sealed cavity, which remains constant, and the pressure in the surrounding environment, which fluctuates due to processing.

[0006] When a wafer with such a warped surface is used in a MEMS device, there is room for improvement in that the fine parts on the wafer cannot be machined into the desired shape, the dimensional processing precision is insufficient, etc. In particular, when fabricating an optical deflection element as a MEMS device, there is concern that if the processing precision of the shape and dimensions of the fine parts is insufficient, the resonance frequency cannot be adjusted to the desired frequency, or there will be variation between optical deflection elements.

[0007] The present invention has been made in view of the above, and has an object to provide a semiconductor device having a highly accurate structure provided on a cavity SOI wafer. [Means for solving the problem]

[0008] In order to solve the above problems and achieve the object, the present invention provides a method for manufacturing a semiconductor device comprising: a fixing member having a first wafer and a second wafer bonded to the first wafer; and a functional part formed on the fixing member and realizing a predetermined function, the first wafer being: On the side to be bonded to the second wafer, A support layer and an active layer provided on the support layer, the active layer comprising: Between the first wafer and the second wafer, a first cavity portion and a second cavity portion communicating the first cavity portion with an outside of the fixing member; is the shape that is formed , characterized in that Effect of the Invention

[0009] The present invention has an effect of providing a semiconductor device having a highly accurate structure provided on a cavity SOI wafer. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a system configuration of an optical scanning system according to the first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a hardware configuration of the optical scanning system. [Diagram 3] FIG. 3 is a diagram illustrating a functional configuration of the control device. [Figure 4]FIG. 4 is a flowchart showing the flow of optical scanning of the scanned surface by the optical scanning system. [Diagram 5] FIG. 5 is a diagram for explaining packaging of the optical deflector. [Figure 6] FIG. 6 is a plan view showing an example of the configuration of the optical deflector. [Figure 7] FIG. 7 is a cross-sectional view showing an example of the configuration of an optical deflector. [Figure 8] FIG. 8 is a cross-sectional view showing a part of the configuration of the optical deflector. [Figure 9] FIG. 9 is a diagram for explaining a method for manufacturing a cavity SOI wafer. [Figure 10] FIG. 10 is a diagram illustrating a conventional cavity SOI wafer. [Figure 11] FIG. 11 is a diagram illustrating a conventional cavity SOI wafer. [Figure 12] FIG. 12 is a diagram illustrating an example of a manufacturing process of an optical deflector. [Figure 13] FIG. 13 is a diagram showing an example of a groove pattern. [Figure 14] FIG. 14 is a plan view showing another example of the configuration of the optical deflector. [Figure 15] FIG. 15 is a plan view illustrating an example of the configuration of the MEMS scanner according to the second embodiment. As illustrated in FIG. [Figure 16] FIG. 16 is a cross-sectional view showing an example of the configuration of a MEMS scanner. [Figure 17] FIG. 17 is a diagram showing an example of a groove pattern. [Figure 18] FIG. 18 is a diagram showing another example of a groove pattern. [Figure 19] FIG. 19 is a diagram showing an automobile provided with a head-up display device having an optical deflector according to the second embodiment. [Figure 20] FIG. 20 is a block diagram showing a configuration of a head-up display device. [Figure 21] FIG. 21 is a diagram illustrating an optical writing device in the third embodiment. [Figure 22] FIG. 22 is a diagram showing the configuration of the main part of the optical writing device. [Figure 23] FIG. 23 is a diagram showing an automobile provided with a laser radar device in the fourth embodiment. [Figure 24] FIG. 24 is a block diagram of a main part of a laser radar device according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a semiconductor device and a method for manufacturing the semiconductor device will be described in detail with reference to the accompanying drawings.

[0012] (Outline of MEMS device) First, in order to explain the semiconductor device and the manufacturing method of the semiconductor device according to the embodiment, an outline of a MEMS (Micro Electro Mechanical Systems) device will be explained. MEMS devices have been developed that use semiconductor technology to form functional parts that realize predetermined functions on silicon wafers (Si wafers). For example, acceleration sensors, pressure sensors, mirror devices, etc. are known as such MEMS devices.

[0013] In the case of an acceleration sensor, a weight structure supported by beams on all four sides is formed by perforating or thinning part of a silicon wafer using a process such as etching. Acceleration is detected by detecting the displacement of the weight due to inertial force in response to external acceleration through the deformation of the beams on all four sides.

[0014] A pressure sensor is formed by forming a membrane part on a thin film and sealing one side of the membrane part to create a vacuum. The pressure sensor formed in this way detects pressure by detecting the deformation of the membrane due to pressure fluctuations.

[0015] Known mirror devices include a scanning mirror device in which a mirror portion supported by a beam structure scans along one or two axes.

[0016] (First embodiment) Hereinafter, as a first embodiment, an optical scanning system to which a scanning mirror device, which is one of such MEMS devices, is applied will be described.

[0017] (System Configuration) Fig. 1 is a diagram showing a system configuration of an optical scanning system according to a first embodiment. As shown in Fig. 1, an optical scanning system 10 includes a control device 11, a light source device 12, and an optical deflector (optical deflection element) 13, which is a semiconductor device having a reflecting surface 14. The optical deflector 13 is a scanning mirror device. In this optical scanning system 10, under the control of the control device 11, the light irradiated from the light source device 12 is deflected by the reflecting surface 14 of the optical deflector 13, and optically scans the light onto a surface 15 to be scanned.

[0018] The control device 11 is an electronic circuit unit including, for example, a CPU (Central Processing Unit) and an FPGA (Field-Programmable Gate Array). The optical deflector 13 is, for example, a MEMS (Micro Electromechanical Systems) device having a reflecting surface 14 that is a reflecting member, and the reflecting surface 14 is movable. The light source device 12 is, for example, a laser device that irradiates a laser. The scanned surface 15 is, for example, a screen.

[0019] The control device 11 generates control commands for the light source device 12 and the optical deflector 13 based on the acquired optical scanning information, and outputs drive signals to the light source device 12 and the optical deflector 13 based on the control commands.

[0020] The light source device 12 emits light based on the input drive signal.

[0021] The optical deflector 13 moves the reflecting surface 14 in at least one or two axial directions based on the input drive signal.

[0022] As a result, the optical scanning system 10 can project any image onto the scanned surface 15, for example, by controlling the control device 11 based on image information, which is an example of optical scanning information, to move the reflective surface 14 of the optical deflector 13 back and forth in two axial directions, and deflecting the illumination light from the light source device 12 that enters the reflective surface 14 to perform optical scanning.

[0023] (Hardware configuration) Next, Fig. 2 is a diagram showing a hardware configuration of the optical scanning system 10. As shown in Fig. 2, the optical scanning system 10 includes a control device 11, a light source device 12, and an optical deflector 13, which are electrically connected to each other.

[0024] Of these, the control device 11 includes a CPU 20, a RAM (Random Access Memory), a ROM (Read Only Memory), an FPGA 23, an external I / F 24, a light source device driver 25, and an optical deflector driver .

[0025] The CPU 20 is a calculation device that reads out programs and data from a storage device such as a ROM 22 onto a RAM 21 and executes processing to realize the overall control and functions of the control device 11.

[0026] The RAM 21 is a volatile storage device that temporarily stores programs and data.

[0027] The ROM 22 is a non-volatile storage device that can retain programs and data even when the power is turned off, and stores processing programs and data that the CPU 20 executes to control each function of the optical scanning system 10.

[0028] The FPGA 23 is a circuit that outputs control signals suitable for the light source device driver 25 and the optical deflector driver 26 in accordance with the processing of the CPU 20 .

[0029] The external I / F 24 is, for example, an interface with an external device, a network, etc. The external device includes, for example, a higher-level device such as a PC (Personal Computer), and a storage device such as a USB memory, an SD card, a CD, a DVD, a HDD, an SSD, etc. Furthermore, the network is, for example, a CAN (Controller Area Network) or a LAN (Local Area Network) of an automobile, the Internet, etc. The external I / F 24 may have a configuration that enables connection or communication with an external device, and an external I / F 24 may be provided for each external device.

[0030] The light source device driver 25 is an electric circuit that outputs a drive signal such as a drive voltage to the light source device 12 in accordance with an input control signal.

[0031] The optical deflector driver 26 is an electric circuit that outputs a drive signal, such as a drive voltage, to the optical deflector 13 in accordance with an input control signal.

[0032] In the control device 11, the CPU 20 acquires optical scanning information from an external device or a network via the external I / F 24. Note that any configuration may be used as long as the CPU 20 can acquire the optical scanning information, and the optical scanning information may be stored in the ROM 22 or FPGA 23 in the control device 11, or a storage device such as an SSD may be newly provided in the control device 11 to store the optical scanning information in the storage device.

[0033] Here, the optical scanning information is information indicating how to scan the scanned surface 15 with light, and for example, when an image is displayed by optical scanning, the optical scanning information is image data. Also, for example, when optical writing is performed by optical scanning, the optical scanning information is writing data indicating the writing order and writing locations. In addition, for example, when object recognition is performed by optical scanning, the optical scanning information is irradiation data indicating the timing and irradiation range of irradiating light for object recognition.

[0034] (Functional configuration of the control device) 3 is a diagram showing the functional configuration of the control device 11. The control device 11 realizes the functions of a control unit 30 and a drive signal output unit 31 according to instructions from the CPU 20 and the hardware configuration shown in FIG.

[0035] The control unit 30 is realized by, for example, the CPU 20, the FPGA 23, etc., and acquires optical scanning information from an external device, converts the optical scanning information into a control signal, and outputs it to the drive signal output unit 31. For example, the control unit 30 acquires image data from an external device, etc. as optical scanning information, generates a control signal from the image data by performing a predetermined process, and outputs it to the drive signal output unit 31.

[0036] The drive signal output unit 31 is realized by the light source device driver 25, the optical deflector driver 26, etc., and outputs a drive signal to the light source device 12 or the optical deflector 13 based on an input control signal. The drive signal output unit 31 may be provided for each target to which the drive signal is output, for example.

[0037] The drive signal is a signal for controlling the drive of the light source device 12 or the optical deflector 13. For example, in the light source device 12, the drive signal is a drive voltage that controls the irradiation timing and irradiation intensity of light irradiated from the light source. Also, in the optical deflector 13, the drive signal is a drive voltage that controls the timing and operating range of the reflective surface 14 of the optical deflector 13. Note that the control device 11 may obtain the irradiation timing and light receiving timing of light irradiated from the light source from an external device such as the light source device 12 or a light receiving device, and synchronize these with the drive of the optical deflector 13.

[0038] (Optical scanning processing) Fig. 4 is a flowchart showing the flow of optical scanning of the scanned surface 15 by the optical scanning system 10. In step S11 of the flowchart in Fig. 4, the control unit 30 acquires optical scanning information from an external device or the like.

[0039] In step S12, the control unit 30 generates a control signal from the acquired optical scanning information and outputs the control signal to the drive signal output unit 31.

[0040] In step S13, the drive signal output unit 31 outputs a drive signal to the light source device 12 and the optical deflector 13 based on the input control signal.

[0041] In step S14, the light source device 12 irradiates light based on the input drive signal. Also, the optical deflector 13 operates the reflecting surface 14 based on the input drive signal. By driving the light source device 12 and the optical deflector 13, the light is deflected in an arbitrary direction and optical scanning is performed.

[0042] In the optical scanning system 10, one control device 11 has devices and functions for controlling the light source device 12 and the optical deflector 13, but this is not limited to this, and the devices may be provided separately, such as a control device for the light source device and a control device for the optical deflector.

[0043] In the optical scanning system 10, the function of the control unit 30 of the light source device 12 and the optical deflector 13 and the function of the drive signal output unit 31 are provided in one control device 11, but these functions may exist separately, for example, a drive signal output device having the drive signal output unit 31 may be provided separately from the control device 11 having the control unit 30. Note that, in the optical scanning system 10, the optical deflector 13 having the reflecting surface 14 and the control device 11 may constitute an optical deflection system that performs optical deflection.

[0044] (Packaging) Fig. 5 is a diagram for explaining packaging of the optical deflector 13. As shown in Fig. 5, the optical deflector 13 is attached to an attachment member 802 disposed inside a packaging member 801, and is packaged by covering a part of the packaging member 801 with a transparent member 803 and sealing it.

[0045] Furthermore, an inert gas such as nitrogen is sealed inside the package member 801. This suppresses deterioration of the optical deflector 13 due to oxidation, and improves durability against environmental changes such as temperature.

[0046] (Structure of the optical deflector) 6 is a plan view showing an example of the configuration of the optical deflector 13, FIG. 7 is a cross-sectional view showing an example of the configuration of the optical deflector 13, and FIG. 8 is a cross-sectional view showing a part of the configuration of the optical deflector 13.

[0047] As shown in Figures 6 to 8, the optical deflector 13 has a mirror section 101 that reflects incident light, first driving sections 110a, 110b connected to the mirror section 101 and driving the mirror section 101 around a first axis parallel to the Y axis, a first support section 120 that is a first support member that supports the mirror section 101 and the first driving sections 110a, 110b, second driving sections 130a, 130b that are driving sections connected to the first support section 120 and driving the mirror section 101 and the first driving sections 110a, 110b around a second axis (axis perpendicular to the first axis) parallel to the X axis, a second support section 140 that is a second support member that supports the second driving sections 130a, 130b, and an electrode connection section 150 that is electrically connected to the first driving sections 110a, 110b, the second driving sections 130a, 130b, and the control section 30. The mirror section 101 and the first driving sections 110a and 110b function as a movable section. The first supporting section 120 and the second supporting section 140 form a fixed member.

[0048] The optical deflector 13 is formed integrally with each of its constituent parts by forming functional parts such as the reflective surface 14, first piezoelectric driving parts 112a, 112b, second piezoelectric driving parts 131a-131f, 132a-132f, and electrode connection part 150 on an SOI substrate, which is a cavity SOI (Silicon On Insulator) wafer formed by bonding another wafer to a wafer that has been previously patterned to create a hollow structure.

[0049] As shown in Fig. 7 and Fig. 8, the SOI substrate is a substrate in which a silicon oxide layer 162 is provided on a first silicon layer made of single crystal silicon (Si), and a second silicon layer and a third silicon layer made of single crystal silicon are further provided on the silicon oxide layer 162. Hereinafter, the first silicon layer is referred to as a silicon support layer 161, the second silicon layer is referred to as a silicon active layer 163, and the third silicon layer is referred to as a silicon active layer 164. The silicon active layers 163 and 164 are collectively referred to as a silicon active layer 165. The silicon oxide layer 162 does not necessarily have to be provided. The silicon oxide layer 162 is not limited to being provided at the above-mentioned location, and may be formed arbitrarily between the silicon layers.

[0050] The silicon active layer 163 and the silicon active layer 164 have a smaller thickness in the Z-axis direction than in the X-axis direction or the Y-axis direction, and therefore function as an elastic portion having elasticity.

[0051] The SOI substrate does not necessarily have to be flat, and may have a curvature, etc. Also, the material used to form the optical deflector 13 is not limited to the SOI substrate, as long as it can be integrally molded by etching or the like and can be partially made elastic.

[0052] Here, a method for fabricating a cavity SOI wafer will be described.

[0053] 9 is a diagram for explaining a method for fabricating a cavity SOI wafer. As shown in FIG. 9, a cavity SOI wafer is fabricated using a wafer 2, which is a first wafer in which a groove pattern 301, which is a first cavity, is formed in advance, and a wafer 1, which is a second wafer different from the wafer 2. Then, the wafer 2 is bonded to the wafer 1 to obtain a cavity SOI wafer 3. The materials of the wafer 1 and the wafer 2 are generally silicon or glass, but other materials may be used.

[0054] As shown in FIG. 9, in this embodiment, when patterning to form a pattern on the wafer 2, in addition to the groove pattern 301, a hole-forming groove pattern 302, which is a second cavity that communicates the groove pattern 301 with the outer periphery of the wafer, is formed. The width of the hole-forming groove pattern 302 is usually about 50 μm, and is at most about 100 μm. The hole-forming groove pattern 302 is formed in the gap between the chips arranged in a checkerboard pattern on the wafer 2. The depth of the hole-forming groove pattern 302 is the same as that of the groove pattern 301. The depth of the hole-forming groove pattern 302 may be shallower than that of the groove pattern 301. Thereafter, the wafer 1 and the wafer 2 are bonded to form a cavity SOI wafer 3.

[0055] Here, Figures 10 and 11 are diagrams explaining a conventional cavity SOI wafer. As mentioned above, wafers made of silicon or glass are used to manufacture MEMS. Such wafers are generally solid, but wafers with a hollow structure called cavity SOI wafers can also be used. Cavity SOI wafers are realized by bonding a wafer with a groove pattern already formed on it to another wafer. At this time, the groove pattern formed beforehand becomes the hollow part (cavity) of the wafer, and the cavity part is sealed by bonding.

[0056] As shown in the cross section of a cavity SOI wafer in Figure 10, a cavity SOI wafer 6 is formed by bonding a wafer 5 with a groove pattern formed thereon to a wafer 4, and the cavity portion 7 has a sealed hollow structure. The pressure inside the cavity portion 7 is determined by the pressure during bonding, and is generally a vacuum, but can be any value depending on the bonding method. When processing such a cavity SOI wafer 6 to fabricate an optical deflection element, it is necessary to perform uniform processing within the element surface and within the wafer surface, and therefore the flatness of the wafer surface is important.

[0057] The bonding process for producing a cavity SOI wafer is generally performed under vacuum, so the inside of the cavity of the wafer is vacuum. However, if the cavity SOI wafer is placed in the atmosphere when the wafer 4, which is the top layer of the wafer, is a thin film with a thickness of 300 μm or less, as shown in the cross section of the cavity SOI wafer in FIG. 11, the pressure difference between the cavity part 7 and the external environment causes distortion on the wafer surface 8 of the cavity part 7, and the flatness of the wafer surface is lost. If an optical deflection element is produced by processing such a non-flat cavity SOI wafer, there is room for improvement in that it is difficult to obtain a desired reflection angle when a mirror is formed on the wafer surface 8, and it is difficult to obtain a desired driving characteristic due to non-uniform film stress when a piezoelectric film is formed on the wafer surface 8. Note that, although FIG. 10 and FIG. 11 show a concave distortion with respect to the wafer surface 8 as an example, there is also a case where the distortion is convex, and even in that case, the above-mentioned concerns arise.

[0058] 9, in this embodiment, a hole-forming groove pattern 302 that connects the groove pattern 301 to the outer periphery of the wafer is formed in the wafer 2, so that the groove pattern 301 that constitutes the cavity is opened to the outside via the hole-forming groove pattern 302. As a result, the pressure inside the groove pattern 301 that constitutes the cavity is always equal to the outside pressure, and distortion of the surface layer due to the pressure difference can be suppressed.

[0059] Returning to FIG. 6, the mirror section 101 is composed of, for example, a circular mirror section base 102 and a reflecting surface 14 formed on the +Z side surface of the mirror section base. The mirror section base 102 is composed of, for example, a silicon active layer 165 (see FIG. 7). The reflecting surface 14 is composed of, for example, a metal thin film containing aluminum, gold, silver, or the like. The mirror section 101 may also have a rib formed on the -Z side surface of the mirror section base 102 for reinforcing the mirror section. The rib is composed of, for example, a silicon support layer 161 and a silicon oxide layer 162, and can suppress distortion of the reflecting surface 14 caused by movement.

[0060] The first driving units 110a, 110b are composed of two torsion bars 111a, 111b each extending in the first axial direction and supporting the mirror unit 101 movably, the two torsion bars 111a, 111b having one end connected to the mirror unit base 102, and first piezoelectric driving units 112a, 112b having one end connected to the torsion bars 111a, 111b and the other end connected to the inner periphery of the first support unit 120.

[0061] 8, the torsion bars 111a, 111b are composed of a silicon active layer 165. The first piezoelectric driving parts 112a, 112b are composed of a lower electrode 201, a piezoelectric part 202, and an upper electrode 203, which are formed in this order on the +Z side surface of the silicon active layer 165, which is an elastic part. The upper electrode 203 and the lower electrode 201 are composed of, for example, gold (Au) or platinum (Pt). The piezoelectric part 202 is composed of, for example, PZT (lead zirconate titanate), which is a piezoelectric material.

[0062] 6 and 7, the first supporting section 120 is composed of, for example, a silicon supporting layer 161, a silicon oxide layer 162, and silicon active layers 163 and 164. The first supporting section 120 is a rectangular support body formed so as to surround the mirror section 101.

[0063] The second driving parts 130a and 130b are a pair of driving beams that support the torsion bars 111a and 111b in a displaceable manner. The second driving parts 130a and 130b are composed of a plurality of second piezoelectric driving parts 131a to 131f, 132a to 132f that are connected in a folded manner, for example, and one end of the second driving parts 130a and 130b is connected to the outer periphery of the first support part 120, and the other end is connected to the inner periphery of the second support part 140. At this time, the connection part between the second driving part 130a and the first support part 120, the connection part between the second driving part 130b and the first support part 120, the connection part between the second driving part 130a and the second support part 140, and the connection part between the second driving part 130b and the second support part 140 are point-symmetrical with respect to the center of the reflection surface 14.

[0064] 6 and 7, the second piezoelectric driving units 130a and 130b are configured by forming a lower electrode 201, a piezoelectric unit 202, and an upper electrode 203 in this order on the +Z side surface of the silicon active layer 164, which is the elastic unit. The upper electrode 203 and the lower electrode 201 are configured from, for example, gold (Au) or platinum (Pt). The piezoelectric unit 202 is configured from, for example, PZT (lead zirconate titanate), which is a piezoelectric material.

[0065] In this embodiment, as described above, the first piezoelectric actuators 112a and 112b have a silicon active layer 165 as a base, while the second piezoelectric actuators 130a and 130b have a silicon active layer 164 as a base. That is, the silicon active layer 165 and the silicon active layer 164 have different thicknesses. By making the base thicknesses different in this way, it is possible to provide elasticity suitable for the function of each member.

[0066] Returning to Figure 6, the second support section 140 is a rectangular support member composed of, for example, a silicon support layer 161, a silicon oxide layer 162, and a silicon active layer 165, and is formed to surround the mirror section 101, the first drive sections 110a, 110b, the first support section 120, and the second drive sections 130a, 130b.

[0067] The electrode connection part 150 is formed, for example, on the surface on the +Z side of the second support part 140, and is electrically connected to the first piezoelectric actuators 112a, 112b, the upper electrodes 203 and lower electrodes 201 of the second piezoelectric actuators 131a to 131f, and the control device 11 via electrode wiring such as aluminum (Al). The upper electrodes 203 and the lower electrodes 201 may each be directly connected to the electrode connection part, or may be indirectly connected by connecting the electrodes to each other, for example.

[0068] In this embodiment, an example has been described in which the piezoelectric portion 202 is formed only on one surface (the +Z side surface) of the silicon active layer 163, which is the elastic portion. However, the piezoelectric portion 202 may be provided on another surface (for example, the -Z side surface) of the elastic portion, or may be provided on both one surface and the other surface of the elastic portion.

[0069] In addition, as long as the mirror unit 101 can be driven around the first axis or the second axis, the shape of each component is not limited to the shape in the embodiment. For example, the torsion bars 111a and 111b and the first piezoelectric drive units 112a and 112b may have a shape with a curvature.

[0070] Furthermore, an insulating layer made of a silicon oxide film may be formed on at least one of the +Z side surface of the upper electrode 203 of the first driving units 110a and 110b, the +Z side surface of the first support unit, the +Z side surface of the upper electrode 203 of the second driving units 130a and 130b, and the +Z side surface of the second support unit. In this case, electrode wiring is provided on the insulating layer, and the insulating layer is partially removed or not formed as an opening only at the connection spot where the upper electrode 203 or the lower electrode 201 is connected to the electrode wiring, thereby increasing the design freedom of the first driving units 110a and 110b, the second driving units 130a and 130b, and the electrode wiring, and further suppressing short circuits due to contact between the electrodes. The silicon oxide film also functions as an anti-reflection material.

[0071] Next, the process for manufacturing the optical deflector 13 will be described.

[0072] Here, Fig. 12 is a diagram illustrating an example of a manufacturing process of the optical deflector 13. First, as shown in Fig. 12(a), a groove pattern 303 is formed in an SOI wafer 2. The groove pattern 303 includes a groove pattern 301 and a hole-forming groove pattern 302. The groove pattern 301 is a groove for forming a cavity portion, and the hole-forming groove pattern 302 is a groove for forming a hole that communicates between the cavity portion and the wafer side surface. The SOI wafer 2 includes a silicon support layer 161, a silicon oxide layer 162, and a silicon active layer 163.

[0073] Next, as shown in FIG. 12(b), a wafer 1 other than the SOI wafer 2 is bonded to the SOI wafer 2 to form a three-layer cavity SOI wafer 4.

[0074] Next, as shown in FIGS. 12(c) to (e), a reflective film 14 and functional films 201 to 203 are formed on the triple-layer cavity SOI wafer 4, and etching is performed from the front and back surfaces to form a structure.

[0075] 13 is a diagram showing an example of groove pattern 303. As shown in FIG. 12, the shape of groove pattern 301 which becomes a cavity portion is determined by the shapes of the member made of silicon active layer 165 and the member made of silicon active layer 165, silicon oxide layer 162, and silicon support layer 161.

[0076] As shown in FIG. 13, of groove pattern 301, the groove portion surrounded on all four sides by first support portion 120, first drive portions 110a, 110b, and mirror portion 101 is referred to as groove portion 301a, the portion of the groove portion surrounded by first support portion 120 excluding groove portion 301a is referred to as groove portion 301b, which is a third cavity portion, and the portion of the groove portion surrounded by second support portion 140 excluding groove portions 301a and 301b is referred to as groove portion 301c, which is a fourth cavity portion.

[0077] The hole-forming groove pattern 302 is a groove pattern that connects the grooves 301a to 301c with the outside of the wafer. The hole-forming groove pattern 302 includes a groove 302a, a groove 302b, and a groove 302c.

[0078] Groove portions 302a and 302b are groove patterns that respectively connect groove portions 301a and 301b to groove portion 301c. Groove portion 302c is a groove pattern that connects groove portion 301c to the outside of the wafer.

[0079] As described above, the groove pattern 301 is closed in the XY plane by itself, but is opened to the outside of the wafer by the hole forming groove pattern 302 .

[0080] The locations where the grooves 302a and 302b are formed in Fig. 13 are just an example. The grooves 302a and 302b may be provided in locations other than those shown in Fig. 13, but it is preferable that the grooves 302a and 302b are arranged symmetrically along the second axis. With this configuration, it is possible to prevent the first support part 120 from becoming eccentric.

[0081] 13, one each of the grooves 302a and 302b is disposed on the second axis, but multiple grooves may be provided. In this case, it is preferable to dispose them line-symmetrically about the second axis, which can prevent eccentricity of the first support part 120.

[0082] 13 is an example. The groove 302c may be provided at a location other than the location shown in FIG. 13. However, since the strength of the second support 140 is reduced by the formation of the groove 302c, it is preferable to provide the groove 302c at a location other than the electrode connection 150 where pressure is applied during wire bonding. In particular, the groove 302c is disposed at the connection portion between the second drive units 130a, 130b and the second support 140 (attachment position to the second support 140). The width of the groove 302c disposed at the connection portion between the second drive units 130a, 130b and the second support 140 is the same as the width of the second drive units 130a, 130b, or wider than the width of the second drive unit 131. With this configuration, a gap is formed directly below the connection portion between the second drive units 130a, 130b and the second support 140, and the second support 140 is not restrained. This makes it possible to increase the deflection angle of the second drive parts 130a, 130b, and also to reduce stress concentration when the second drive parts 130a, 130b are deformed, thereby increasing the breaking strength.

[0083] When the optical deflector 13 is produced by a conventional device production process flow, the hole formation groove pattern 302 is not formed in the step of Fig. 12(a) as shown in Fig. 13. In the conventional device production process flow, a silicon active layer 163 is provided instead of the hole formation groove pattern 302.

[0084] [Controller control details] Next, details of the control by the control device 11 that drives the first drive section and the second drive section of the optical deflector will be described.

[0085] When a positive or negative voltage is applied in the polarization direction, the piezoelectric section 202 of the first driving section 110a, 110b and the second driving section 130a, 130b undergoes deformation (e.g., expansion and contraction) proportional to the potential of the applied voltage, thereby exerting the so-called inverse piezoelectric effect. The first driving sections 110a, 110b and the second driving sections 130a, 130b move the mirror section 101 by utilizing the inverse piezoelectric effect.

[0086] In this case, the angle formed by the XY plane and the reflecting surface 14 when the reflecting surface 14 of the mirror section 101 is tilted in the +Z direction or the -Z direction with respect to the XY plane is called the deflection angle. In this case, the +Z direction is the positive deflection angle, and the -Z direction is the negative deflection angle.

[0087] First, the control of the control device 11 that drives the first drive unit will be described.

[0088] In the first driving units 110a and 110b, when a driving voltage is applied in parallel to the piezoelectric units 202 of the first piezoelectric driving units 112a and 112b via the upper electrode 203 and the lower electrode 201, each piezoelectric unit 202 is deformed. The first piezoelectric driving units 112a and 112b are bent and deformed by the action of the deformation of the piezoelectric units 202. As a result, a driving force about the first axis acts on the mirror unit 101 via the twist of the two torsion bars 111a and 111b, and the mirror unit 101 moves about the first axis. The driving voltage applied to the first driving units 110a and 110b is controlled by the control device 11.

[0089] Therefore, the control device 11 applies a driving voltage having a predetermined sinusoidal waveform in parallel to the first piezoelectric driving units 112a, 112b of the first driving units 110a, 110b, so that the mirror unit 101 can be moved around the first axis with a period of the driving voltage having a predetermined sinusoidal waveform.

[0090] In particular, for example, when the frequency of the sinusoidal waveform voltage is set to approximately 20 kHz, which is similar to the resonant frequency of the torsion bars 111a and 111b, the mirror portion 101 can be made to resonate and vibrate at approximately 20 kHz by utilizing the mechanical resonance caused by the twisting of the torsion bars 111a and 111b.

[0091] Thus, according to this embodiment, when the groove pattern 301 that becomes the cavity portion is formed on the SOI wafer 2, the hole forming groove pattern 302 that communicates the cavity portion with the wafer side surface is formed. After that, another wafer 1 is bonded to form a cavity SOI wafer 4. In the cavity SOI wafer 4 thus fabricated, the cavity portion is opened to the outside from the wafer side surface through the hole forming groove pattern 302. Therefore, the pressure inside the cavity is equal to the pressure of the external environment, so that the wafer surface is kept flat. By forming the hole forming groove pattern 302 that communicates the inside of the cavity with the outside of the wafer in this way on the wafer 2, the pressure inside the cavity is always equal to the pressure of the surrounding environment, and distortion of the wafer surface due to the pressure difference between the inside of the cavity and the surrounding environment can be prevented, so that a semiconductor device with a high accuracy of the structure provided on the cavity SOI wafer can be provided.

[0092] In this embodiment, as shown in FIG. 6, the optical deflector 13 is a cantilever type optical deflector in which the first piezoelectric actuators 112a and 112b extend from the torsion bars 111a and 111b in the +X direction, but the present invention is not limited to this as long as the reflecting surface is moved by the piezoelectric parts to which a voltage is applied. Here, FIG. 14 is a plan view showing another example of the configuration of the optical deflector 13. For example, as shown in FIG. 14, a double-supported type optical deflector having first piezoelectric actuators 212a and 212b extending from the torsion bars 211a and 211b in the +X direction and first piezoelectric actuators 212c and 212d extending in the -X direction may be used. Also, the reflecting surface may be moved in only one axial direction.

[0093] (Second embodiment) Next, a second embodiment will be described.

[0094] The second embodiment differs from the first embodiment in that a MEMS scanner is used as an optical deflector. In the following description of the second embodiment, the description of the same parts as in the first embodiment will be omitted, and only the differences from the first embodiment will be described.

[0095] Here, FIG. 15 is a plan view showing an example of the configuration of the MEMS scanner 14A according to the second embodiment, and FIG. 16 is a cross-sectional view showing the example of the configuration of the MEMS scanner 14A.

[0096] The MEMS scanner 14A is a semiconductor device, and is a single-mirror scanning device manufactured by MEMS (Micro Electro Mechanical Systems) technology. As shown in Fig. 15, the MEMS scanner 14A has a movable part 144 having a reflection mirror 145, which is a mirror part equipped with a reflection member, and serpentine beam parts 146, which are a pair of drive beams that support the movable part 144 on both sides of the movable part 144. One end of each of the serpentine beam parts 146 is fixed to a support substrate 143, and the other end is connected to the movable part 144. The support substrate 143 is a part of the fixed member.

[0097] 16, the movable part 144 is composed of a silicon active layer 164. The movable part 144 also has a mirror-reinforcing rib 148, which is made of a silicon active layer 163, a silicon oxide layer 162, and a silicon support layer 161, on the surface of the silicon active layer 164 opposite the reflecting mirror 145. The rib 148 is a part of the fixed member.

[0098] Each of the meandering beams 146 has first piezoelectric members 147a and second piezoelectric members 147b arranged alternately, forming a meandering pattern with a repeated folded structure via multiple folded parts. Voltage signals of opposite phases are applied to the adjacent first piezoelectric members 147a and second piezoelectric members 147b, causing the meandering beams 146 to warp in the Z direction.

[0099] As shown in FIG. 16, each of the serpentine beams 146 is made of a silicon active layer 165 .

[0100] The first piezoelectric member 147a and the second piezoelectric member 147b adjacent to each other are deflected in opposite directions. The deflections in the opposite directions are accumulated, causing the movable part 144 including the reflecting mirror 145 to rotate back and forth around the rotation axis A as the center of rotation.

[0101] By applying sine waves in opposite phase to the first piezoelectric member 147a and the second piezoelectric member 147b, which have a drive frequency that matches the mirror resonance mode with the rotation axis A as the center of rotation, a large rotation angle can be obtained with a low voltage.

[0102] The MEMS scanner 14A performs optical scanning in one axial direction (X direction). For detection and measurement in the vertical direction (Y direction), the number of layers can be increased by switching the emission of multiple light-emitting element groups 110 arranged at intervals in the Y direction.

[0103] Next, the groove pattern 303 of the MEMS scanner 14A will be described.

[0104] 17 is a diagram showing an example of groove pattern 303. As shown in Fig. 17, the shape of groove pattern 301, which is a first hollow portion that becomes a cavity portion, is determined by the shapes of a member made of silicon active layer 165 and a member made of silicon active layer 165, silicon oxide layer 162, and silicon support layer 161.

[0105] As shown in FIG. 17, in groove pattern 301, the portion surrounded by ribs 148 is groove portion 301a, and the portion inside surrounded by support substrate 143 other than groove portion 301a is groove portion 301b, which is a third cavity portion.

[0106] The hole-forming groove pattern 302 is a groove pattern that connects a groove portion 301a, a groove portion 301b, and the outside of the wafer. The hole-forming groove pattern 302 includes a groove portion 302a, a groove portion 302b, and a groove portion 302c.

[0107] Groove 302a is a groove pattern that connects the multiple grooves 301a to each other. Groove 302b is a groove pattern that connects groove 301a to groove 301b. Groove 302c is a groove pattern that connects groove 301b to the outside of the wafer, and is a fourth cavity.

[0108] As described above, the groove pattern 301 is closed in the XY plane by itself, but is opened to the outside of the wafer by the hole forming groove pattern 302 .

[0109] The number and the locations of the grooves 302a, 302b in FIG. 17 are merely an example. A plurality of grooves 302a, 302b may be provided at locations other than those shown in FIG. 17. FIG. 18 is a diagram showing another example of the groove pattern 303. As shown in FIG. 18, an even number of grooves 302a, 302b are provided, and they are arranged so as to be point symmetrical with respect to the center of gravity of the movable part 144. This allows the MEMS scanner 14A to prevent decentering of the movable part 144 and achieve stable movement.

[0110] As shown in FIG. 18, when the serpentine beam portion 146 is disposed symmetrically with respect to the Y axis, the groove portions 302a, 302b are disposed so as to be point-symmetric with respect to the center of gravity of the movable portion 144 and also symmetric with respect to the Y axis.

[0111] Also, it is desirable to arrange grooves 302a more than grooves 302b. By arranging grooves 302a more than grooves 302b, MEMS scanner 14A can reduce the mass of movable part 144 without reducing the strength of rib 148. By reducing the mass of movable part 144 in this way, the stress applied to the beam when dropped is reduced, and therefore MEMS scanner 14A can improve the impact resistance of the entire scanner.

[0112] (Third embodiment) Next, a third embodiment will be described. This third embodiment is an example in which the above-mentioned optical deflector 13 is applied to an image projection device. Fig. 19 is a diagram showing an automobile 400 provided with a head-up display device 500, which is an example of an image projection device. Fig. 20 is a block diagram showing the configuration of the head-up display device 500.

[0113] 19, the head-up display device 500 is installed, for example, near the windshield (windshield 401, etc.) of an automobile 400. Projection light L emitted from the head-up display device 500 is reflected by the windshield 401 and directed toward an observer (driver 402) who is a user.

[0114] This allows the driver 402 to view, as a virtual image, the image projected by the head-up display device 500. Note that a combiner may be installed on the inner wall surface of the windshield, and the user may view a virtual image by projected light reflected by the combiner.

[0115] 20, in a head-up display device 500, laser beams are emitted from red, green, and blue laser light sources 501R, 501G, and 501B. The emitted laser beams pass through an incident optical system including collimator lenses 502, 503, and 504 provided for the respective laser light sources, two dichroic mirrors 505 and 506, and a light amount adjustment unit 507, and are then deflected by the above-mentioned optical deflector 13 having a reflecting surface 14.

[0116] The deflected laser light then passes through a projection optical system consisting of a free curved surface mirror 509, an intermediate screen 510, and a projection mirror 511, and is projected onto a screen.

[0117] In the head-up display device 500, the laser light sources 501R, 501G, and 501B, the collimator lenses 502, 503, and 504, and the dichroic mirrors 505 and 506 are unitized as a light source unit 530 by an optical housing.

[0118] The head-up display device 500 projects an intermediate image displayed on an intermediate screen 510 onto a windshield 401 of an automobile 400, thereby allowing a driver 402 to visually recognize the intermediate image as a virtual image.

[0119] The laser beams of each color emitted from the laser light sources 501R, 501G, and 501B are converted into approximately parallel beams by collimator lenses 502, 503, and 504, respectively, and are combined by two dichroic mirrors 505 and 506. The combined laser beams are adjusted in amount by a light amount adjustment unit 507, and then two-dimensionally scanned by an optical deflector 13 having a reflecting surface 14. The projection light L two-dimensionally scanned by the optical deflector 13 is reflected by a free-form surface mirror 509, where distortion is corrected, and then the light is focused on an intermediate screen 510 to display an intermediate image. The intermediate screen 510 is composed of a microlens array in which microlenses are arranged two-dimensionally, and the projection light L incident on the intermediate screen 510 is magnified in units of the microlens.

[0120] The optical deflector 13 reciprocates the reflecting surface 14 in two axial directions, and two-dimensionally scans the projection light L incident on the reflecting surface 14. The drive control of this optical deflector 13 is performed in synchronization with the light emission timing of the laser light sources 501R, 501G, and 501B.

[0121] The above describes the head-up display device 500 as an example of an image projection device, but the image projection device may be any device that projects an image by performing optical scanning using an optical deflector 13 having a reflective surface 14.

[0122] For example, the present invention can be similarly applied to a projector that is placed on a desk or the like and projects an image onto a display screen, or a head-mounted display device that is mounted on a mounting member that is attached to the observer's head or the like and projects an image onto a reflective / transmissive screen possessed by the mounting member, or projects an image using the eyeball as a screen.

[0123] In addition, the image projection device may be mounted not only on a vehicle or a mounting member, but also on a moving body such as an aircraft, a ship, or a mobile robot, or on a non-moving body such as a work robot that operates a drive object such as a manipulator without moving from its location.

[0124] In this way, by using the semiconductor device according to the present embodiment in an image projection device, it is possible to realize an image projection device with improved processing accuracy of the fine structure processed on the surface of a cavity SOI wafer.

[0125] (Fourth embodiment) Next, a fourth embodiment will be described. This fourth embodiment is an example in which the above-mentioned optical deflector 13 is applied to an optical writing device. Fig. 21 is an example of an image forming apparatus incorporating an optical writing device 600. Fig. 22 is a diagram showing the configuration of a main part of the optical writing device.

[0126] 21, optical writing device 600 is used as a component of an image forming apparatus such as a laser printer 650 having a printer function using laser light. In the image forming apparatus, optical writing device 600 optically writes on a photoconductor drum, which is a scanned surface 15, by optically scanning the photoconductor drum with one or more laser beams.

[0127] As shown in FIG. 22, in an optical writing device 600, laser light from a light source device 12 such as a laser element passes through an imaging optical system 601 such as a collimator lens, and is then deflected in one or two axial directions by an optical deflector 13 having a reflective surface 14.

[0128] The laser light deflected by the optical deflector 13 then passes through a scanning optical system 602 consisting of a first lens 602a, a second lens 602b, and a reflecting mirror unit 602c, and is irradiated onto a surface 15 to be scanned (e.g., a photosensitive drum or photosensitive paper) for optical writing. The scanning optical system 602 forms an image of the light beam in the form of a spot on the surface 15 to be scanned.

[0129] Furthermore, the light source device 12 and the optical deflector 13 having the reflecting surface 14 are driven under the control of the control device 11 .

[0130] In this manner, the optical writing device 600 can be used as a component of an image forming device having a printer function using laser light.

[0131] Furthermore, by changing the scanning optical system to enable optical scanning not only in one axis direction but also in two axes directions, the laser light can be deflected onto thermal media to perform optical scanning, and the laser light can be used as a component of an image forming device such as a laser label device that prints by heating.

[0132] The optical deflector 13 having the reflecting surface 14 applied to the optical writing device described above consumes less power for driving than a rotating polygon mirror using a polygon mirror or the like, and is therefore advantageous in reducing the power consumption of the optical writing device.

[0133] In addition, the wind noise generated by the optical deflector 13 during vibration is smaller than that of the rotating polygon mirror, which is advantageous for improving the quietness of the optical writing device. The optical writing device requires an overwhelmingly smaller installation space than the rotating polygon mirror, and the amount of heat generated by the optical deflector 13 is small, making it easy to reduce the size of the device, which is advantageous for reducing the size of the optical writing device.

[0134] In this way, by using the semiconductor device according to the present embodiment in an optical writing device, it is possible to realize an optical writing device with improved processing accuracy for processing a fine structure on the surface of a cavity SOI wafer.

[0135] (Fifth embodiment) Next, a fifth embodiment will be described. In this fifth embodiment, the above-mentioned optical deflector 13 is provided in a laser radar device, which is an example of an object recognition device. Fig. 23 is a diagram showing an automobile 701 provided with a laser radar device 700. In Fig. 23, the laser radar device 700 optically scans a target direction and receives reflected light from a target object 702 present in the target direction, thereby recognizing the target object 702.

[0136] Fig. 24 is a block diagram of the main parts of a laser radar device 700. As shown in Fig. 24, the laser light emitted from the light source device 12 passes through an incident optical system composed of a collimator lens 703, which is an optical system that converts divergent light into approximately parallel light, and a plane mirror 704, and is scanned in one or two axial directions by an optical deflector 13 having a reflecting surface 14.

[0137] The light is then irradiated onto an object 702 in front of the device through a projection lens 705 and the like which constitute a projection optical system. The driving of the light source device 12 and the optical deflector 13 is controlled by a control device 11. The light reflected by the object 702 is optically detected by a photodetector 709.

[0138] That is, the reflected light passes through a collecting lens 706 and the like, which is a light receiving optical system, and is received by an image sensor 707, which outputs a detection signal to a signal processing circuit 708. The signal processing circuit 708 performs predetermined processing, such as binarization and noise processing, on the input detection signal, and outputs the result to a distance measurement circuit 710.

[0139] The distance measurement circuit 710 recognizes the presence or absence of the target object 702 based on the time difference between when the light source device 12 emits laser light and when the laser light is received by the photodetector 709, or the phase difference between each pixel of the image sensor 707 that receives the light, and further calculates distance information to the target object 702.

[0140] The optical deflector 13 having the reflecting surface 14 is less prone to breakage than a polygonal mirror and is small in size, making it possible to provide a small, highly durable radar device.

[0141] Such a laser radar device is attached to, for example, a vehicle, an aircraft, a ship, a robot, etc. By optically scanning a predetermined range, the presence or absence of an obstacle and the distance to the obstacle can be recognized.

[0142] In the above object recognition device, a laser radar device 700 has been described as an example, but the object recognition device may be any device that performs optical scanning by controlling an optical deflector 13 having a reflective surface 14 with a control device 11, and recognizes an object 702 by receiving reflected light with a photodetector, and is not limited to the above-mentioned embodiment.

[0143] For example, the technology can be applied to biometric authentication, which calculates object information such as shape from distance information obtained by optically scanning a hand or face, and recognizes the target object by referring to a record; security sensors which recognize intruding objects by optically scanning a target range; and components of 3D scanners which calculate and recognize object information such as shape from distance information obtained by optical scanning, and output it as 3D data.

[0144] In this way, by using the semiconductor device according to this embodiment in an object recognition device, it is possible to realize an object recognition device with improved processing accuracy for microstructures processed on the surface of a cavity SOI wafer.

[0145] In the third to fifth embodiments, examples have been shown in which the optical deflector 13 is applied to various devices, but this is not limited to this, and it goes without saying that the MEMS scanner 14A can be applied to various devices.

[0146] Finally, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. The novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, each embodiment and each modification of each embodiment is included in the scope and spirit of the invention, and is included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0147] 1 Second wafer 2. First wafer 13 Semiconductor Devices 14 Reflective material 14A Semiconductor Device 101 Mirror section 111a, 111b Torsion bar 120 First support member 130a, 130b Drive unit 140 Second support member 143 Moving parts 144 Moving parts 145 Reflective parts, mirror parts 146 Pair of driving beams 161 Silicon Support Layer 165 Silicon active layer 301 First Cavity 301b Third Cavity 301c Fourth Cavity 302 Second Cavity [Prior art documents] [Patent documents]

[0148] [Patent Document 1] JP 2019-191158 A

Claims

1. a fixing member having a first wafer and a second wafer bonded to the first wafer; A functional portion that is formed on the fixed member and that realizes a predetermined function; Equipped with The first wafer has a side to be bonded to the second wafer, A support layer and an active layer provided on the support layer; having The active layer is disposed between the first wafer and the second wafer, A first cavity; a second cavity portion communicating the first cavity portion with an outside of the fixing member; is the shape in which A semiconductor device comprising:

2. the support layer is a silicon support layer; The active layer is a silicon active layer.

2. The semiconductor device according to claim 1 .

3. The fixing member has a hollow structure.

3. The semiconductor device according to claim 1 or 2.

4. the functional unit has a movable unit supported by a first support member that is a part of the fixed member, and a drive unit that is supported by a second support member that is a part of the fixed member and is provided on an outer periphery of the first support member and drives the movable unit; the first wafer constituting the fixing member is subjected to at least one patterning to form at least one or more second cavities communicating with a third cavity which is a part of the first cavity and is formed by the first support member, and a fourth cavity which is a part of the first cavity and is formed by the second support member; 4. A semiconductor device according to claim 1, wherein the semiconductor device is a semiconductor substrate.

5. the movable portion includes a mirror portion having a reflective member that reflects light, and a pair of torsion bars having one end connected to the mirror portion and supporting the mirror portion, the driving portion is a pair of driving beams connected to the other end of the torsion bar and supporting the torsion bar in a displaceable manner, The second cavity is formed in the first support member to which each of the actuation beams is connected.

5. The semiconductor device according to claim 4.

6. the movable portion is a mirror portion having a reflective member that reflects light, the driving unit is a pair of driving beams that displaceably supports the mirror unit, the first support member to which the actuation beams are connected and which is provided on a peripheral edge of the reflecting member has the second cavity formed therein; 5. The semiconductor device according to claim 4.

7. The drive unit has a repeated folded structure via a plurality of folded parts.

5. The semiconductor device according to claim 4.

8. The second cavity is disposed at a connection portion between the driving portion and the fixed member.

5. The semiconductor device according to claim 4.

9. The second cavity portion is disposed symmetrically along an axis perpendicular to the movable axis of the movable portion.

5. The semiconductor device according to claim 4.

10. The second cavity portion is disposed in plurality so as to be symmetrical with respect to an axis perpendicular to the movable axis of the movable portion.

5. The semiconductor device according to claim 4.

11. 1. A method for manufacturing a semiconductor device, comprising: A first step of forming an active layer on a support layer of a first wafer; a second step of bonding a second wafer to the side of the first wafer on which the active layer is formed to form a fixing member; a third step of forming a functional portion that realizes a predetermined function on the fixing member; Including, the first step forms the active layer so that a first cavity and a second cavity that communicates with the outside of the fixing member are formed between the first wafer and the second wafer bonded in the second step; 1. A method for manufacturing a semiconductor device comprising the steps of:

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