Method for manufacturing a vibration device and vibration device

Abstract

To provide a method for manufacturing a vibration device having excellent formation accuracy, and a vibration device.SOLUTION: A method for manufacturing a vibration device includes: a SOI substrate preparation step of preparing a SOI substrate in which a silicon oxide layer is interposed between a first silicon layer and a second silicon layer; a second silicon layer patterning step of patterning the second silicon layer by etching to form a support part, a movable electrode, and a stationary electrode on the second silicon layer; a first silicon layer patterning step of patterning the first silicon layer by etching to form a support part and a movable part on the first silicon layer; and a silicon oxide layer removal step of removing the silicon oxide layer between the movable part and the second silicon layer to separate the movable part and the stationary electrode from each other.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a vibration device and a vibration device. [Background technology]

[0002] For example, Patent Documents 1 and 2 each describe an electrostatic induction type vibration power generation element, which both have a fixed electrode unit with a comb-like fixed electrode, a movable unit with a comb-like movable electrode that meshes with the fixed electrode, and a weight placed on the movable unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-065322 [Patent Document 2] US Patent Application Publication No. 2009 / 0140443 Summary of the Invention [Problem to be solved by the invention]

[0004] In the vibration power generation element of Patent Document 1, the movable electrode is arranged planarly with the movable part. Therefore, if an attempt is made to increase the capacitance between the movable electrode and the fixed electrode by increasing the size of the movable electrode, it is necessary to either make the movable part smaller or to increase the size of the entire element. If the movable part is made smaller, the sensitivity of the element may deteriorate, resulting in a decrease in power generation characteristics, while if the entire element is made larger, the mountability of the element becomes poor. In contrast, in the vibration power generation element of Patent Document 2, the movable electrode is arranged overlapping the movable part. Therefore, it is possible to increase the size of the movable electrode and increase the capacitance between the fixed electrode without reducing the size of the movable part or increasing the size of the entire element.

[0005] However, the vibration power generation element of Patent Document 2 is manufactured by preparing two substrates, patterning each of the two substrates into a predetermined pattern using photolithography and etching, and then bonding these two substrates together. This manufacturing method of bonding patterned substrates together results in variations in the bonding between individual substrates. Therefore, it is necessary to ensure a margin to allow for this variation, and it is not possible to sufficiently reduce the gap between the movable electrode and the fixed electrode. This makes it difficult to increase power generation efficiency. [Means for solving the problem]

[0006] The method for manufacturing a vibration device of the present invention includes: a movable portion displaceable in a first direction relative to the support portion; a movable electrode connected to the movable portion; a fixed electrode connected to the support portion and arranged next to the movable electrode in a second direction perpendicular to the first direction, an SOI substrate preparation step of preparing an SOI substrate having a silicon oxide layer interposed between a first silicon layer and a second silicon layer; a second silicon layer patterning step of patterning the second silicon layer by etching to form the support portion, the movable electrode, and the fixed electrode in the second silicon layer; a first silicon layer patterning step of patterning the first silicon layer by etching to form the support portion and the movable portion in the first silicon layer; and a silicon oxide layer removing step of removing the silicon oxide layer between the movable portion and the second silicon layer to separate the movable portion from the fixed electrode.

[0007] The resonating device of the present invention comprises an SOI substrate having a silicon oxide layer interposed between a first silicon layer and a second silicon layer, A support part; a spring portion connected to the support portion; a movable portion connected to the support portion via the spring portion and displaced in a first direction relative to the support portion while elastically deforming the spring portion; a movable electrode connected to the movable portion; a fixed electrode connected to the support portion and arranged next to the movable electrode in a second direction perpendicular to the first direction, the support portion is formed from a stack of the first silicon layer, the silicon oxide layer, and the second silicon layer, the movable portion and the spring portion are formed from the first silicon layer; The movable electrode and the fixed electrode are formed from the second silicon layer. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view of a vibration power generating element according to a preferred embodiment. [Figure 2] FIG. 2 is a plan view of the vibration power generating element of FIG. 1 with a second silicon layer removed. [Figure 3] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 4] 1 is a flowchart showing a manufacturing process of a vibration power generation element. [Figure 5] 10A to 10C are cross-sectional views illustrating a method for manufacturing a vibration power generating element. [Figure 6] 10A to 10C are cross-sectional views illustrating a method for manufacturing a vibration power generating element. [Figure 7] 10A to 10C are cross-sectional views illustrating a method for manufacturing a vibration power generating element. [Figure 8] 10A to 10C are cross-sectional views illustrating a method for manufacturing a vibration power generating element. [Figure 9] 10A to 10C are cross-sectional views illustrating a method for manufacturing a vibration power generating element. [Figure 10] 10A to 10C are cross-sectional views illustrating a method for manufacturing a vibration power generating element. [Figure 11] 10A to 10C are cross-sectional views illustrating a method for manufacturing a vibration power generating element. [Figure 12] 10A to 10C are cross-sectional views illustrating a method for manufacturing a vibration power generating element. [Figure 13] 10A to 10C are cross-sectional views illustrating a method for manufacturing a vibration power generating element. [Figure 14] FIG. 10 is a cross-sectional view showing a modified example of the vibration power generating element. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a vibration device and a vibration device according to the present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings.

[0010] Fig. 1 is a plan view of a vibration power generating element according to a preferred embodiment. Fig. 2 is a plan view of the vibration power generating element of Fig. 1 with a second silicon layer removed. Fig. 3 is a cross-sectional view taken along line AA in Fig. 1. Fig. 4 is a flowchart showing the manufacturing process of the vibration power generating element. Figs. 5 to 13 are cross-sectional views illustrating a method for manufacturing the vibration power generating element. Fig. 14 is a cross-sectional view showing a modified example of the vibration power generating element.

[0011] In each figure except for Figure 4, the X-axis, Y-axis, and Z-axis are shown as three mutually orthogonal axes. The direction along the X-axis, i.e., the direction parallel to the X-axis, is also referred to as the "X-axis direction," the direction along the Y-axis as the "Y-axis direction," and the direction along the Z-axis as the "Z-axis direction." The side of the arrowhead on each axis is also referred to as the "plus side," and the opposite side as the "negative side." The positive side of the Z-axis is also referred to as the "upper," and the negative side of the Z-axis is also referred to as the "lower."

[0012] The vibration power generating element 1 shown in Figures 1 to 3 as a vibration device is an electrostatic induction type vibration power generating element that generates power by being driven by an external force. Such a vibration power generating element 1 is manufactured by patterning an SOI (Silicon on Insulator) substrate 2 using a semiconductor process. The SOI substrate 2 is a substrate formed by inserting a silicon oxide layer 2B between a pair of silicon layers 2A and 2C. For ease of explanation, the lower silicon layer 2A will also be referred to as the first silicon layer 2A, and the upper silicon layer 2C will also be referred to as the second silicon layer 2C below.

[0013] The vibration power generating element 1 has a support portion 3, a spring portion 4 connected to the support portion 3, a movable portion 5 connected to the support portion 3 via the spring portion 4 and displacing in the X-axis direction, which is a first direction, relative to the support portion 3 while elastically deforming the spring portion 4, a movable electrode 6 connected to the movable portion 5, and first and second fixed electrodes 7 and 8 serving as fixed electrodes connected to the support portion 3. In the vibration power generating element 1 configured as described above, when an external force is applied in the X-axis direction, the movable portion 5 vibrates in the X-axis direction while elastically deforming the spring portion 4, and this vibration changes the capacitance between the movable electrode 6 and the first and second fixed electrodes 7 and 8, thereby generating power.

[0014] ≪Support part 3≫ Support section 3 is formed from a stack of first silicon layer 2A, silicon oxide layer 2B, and second silicon layer 2C, and has a frame shape in plan view from the Z-axis direction. The other components are disposed inside support section 3. Second silicon layer 2C of support section 3 is divided into a first fixed electrode connection region 31 to which first fixed electrode 7 is connected and a second fixed electrode connection region 32 to which second fixed electrode 8 is connected, and these regions are insulated from each other. Terminal T1 electrically connected to first fixed electrode 7 is disposed in first fixed electrode connection region 31, and terminal T2 electrically connected to second fixed electrode 8 is disposed in second fixed electrode connection region 32.

[0015] ≪Movable part 5≫ The movable part 5 is formed from the first silicon layer 2A, and is located at the center of the vibration power generation element 1 when viewed from above in the Z-axis direction.

[0016] <Spring part 4> The spring portion 4 is formed from the first silicon layer 2A. This allows the spring portion 4 to be positioned near the center of gravity of the movable portion 5, thereby suppressing unnecessary displacement of the movable portion 5. The spring portion 4 also includes a first spring portion 41 and a second spring portion 42, each of which elastically deforms in the X-axis direction. The first spring portion 41 is located on the positive side of the movable portion 5 in the X-axis direction and connects the end of the movable portion 5 on the positive side in the X-axis direction to the support portion 3. Meanwhile, the second spring portion 42 is located on the negative side of the movable portion 5 in the X-axis direction and connects the end of the movable portion 5 on the negative side in the X-axis direction to the support portion 3. In this way, by supporting the movable portion 5 from both sides in the X-axis direction with the first and second spring portions 41 and 42, the movable portion 5 can be stably vibrated in the X-axis direction.

[0017] <Moveable electrode 6> The movable electrode 6 is formed from the second silicon layer 2C. In addition, the movable electrode 6 overlaps the movable portion 5 in a plan view from the Z-axis direction. The movable electrode 6 is connected to the movable portion 5 and protrudes from the upper surface of the movable portion 5 toward the positive side in the Z-axis direction. Note that the silicon oxide layer 2B is not formed between the movable electrode 6 and the movable portion 5, and the first silicon layer 2A and the second silicon layer 2C are in contact with each other. Therefore, the movable electrode 6 is electrically connected to the first silicon layer 2A, and can be electrically connected to the outside, for example, via the first silicon layer 2A of the support portion 3. This portion is insulated from the first and second fixed electrode connection regions 31 and 32 by the silicon oxide layer 2B. This results in a vibration power generation element 1 that can be easily electrically connected to the outside.

[0018] In this way, by arranging the movable electrode 6 and the movable part 5 so that they overlap in the Z-axis direction, the movable part 5 can be made larger and its mass can be increased without increasing the planar dimensions of the vibration power generation element 1. This improves the sensitivity of the vibration power generation element 1, allowing the movable part 5 to vibrate efficiently even in low frequency bands. Furthermore, because the movable electrode 6 and the first and second fixed electrodes 7, 8 can be formed over a wide range regardless of the size of the movable part 5, the capacitance between the movable electrode 6 and the first and second fixed electrodes 7, 8 can be increased. This allows the amount of power generated by the vibration power generation element 1 to be increased.

[0019] The movable electrode 6 has a plurality of movable electrode fingers 61 extending in the X-axis direction, and these movable electrode fingers 61 are arranged in a matrix. In the illustrated configuration, three columns are arranged in the X-axis direction, each column having a plurality of movable electrode fingers 61 aligned in a comb-like pattern in the Y-axis direction. Hereinafter, for ease of explanation, of these three columns, the column on the positive side in the X-axis direction will be referred to as movable electrode finger group 61A, the central column will be referred to as movable electrode finger group 61B, and the column on the negative side in the X-axis direction will be referred to as movable electrode finger group 61C. However, the number and arrangement of the movable electrode fingers 61 are not particularly limited.

[0020] In addition, the movable electrode 6 is provided with an electret film EL.

[0021] ≪First and second fixed electrodes 7, 8≫ The first fixed electrode 7 and the second fixed electrode 8 are each formed from the second silicon layer 2C. Furthermore, the first fixed electrode 7 and the second fixed electrode 8 each overlap the movable portion 5 in a plan view from the Z-axis direction. Furthermore, the silicon oxide layer 2B between the first and second fixed electrodes 7, 8 and the movable portion 5 has been removed, forming a gap therebetween that is the thickness of the silicon oxide layer 2B.

[0022] The first fixed electrode 7 extends in the X-axis direction and has a plurality of first fixed electrode fingers 71 arranged side by side with the movable electrode fingers 61 in the Y-axis direction. Specifically, the first fixed electrode 7 has a comb-like first fixed electrode finger group 71A having a plurality of first fixed electrode fingers 71 that mesh with the movable electrode finger group 61A from the positive side in the X-axis direction, a comb-like first fixed electrode finger group 71B having a plurality of first fixed electrode fingers 71 that mesh with the movable electrode finger group 61B from the positive side in the X-axis direction, and a comb-like first fixed electrode finger group 71C having a plurality of first fixed electrode fingers 71 that mesh with the movable electrode finger group 61C from the positive side in the X-axis direction. The movable electrode fingers 61 and the first fixed electrode fingers 71 are arranged with a predetermined meshing length in the X-axis direction and with a gap G in the Y-axis direction in a stationary state (neutral state).

[0023] Second fixed electrode 8 extends in the X-axis direction and has a plurality of second fixed electrode fingers 81 arranged side by side with movable electrode fingers 61 in the Y-axis direction. Specifically, second fixed electrode 8 has comb-tooth-shaped second fixed electrode finger group 81A having a plurality of second fixed electrode fingers 81 that mesh with movable electrode finger group 61A from the negative side in the X-axis direction, comb-tooth-shaped second fixed electrode finger group 81B having a plurality of second fixed electrode fingers 81 that mesh with movable electrode finger group 61B from the negative side in the X-axis direction, and comb-tooth-shaped second fixed electrode finger group 81C having a plurality of second fixed electrode fingers 81 that mesh with movable electrode finger group 61C from the negative side in the X-axis direction. In a stationary state (neutral state), movable electrode fingers 61 and second fixed electrode fingers 81 are arranged with a predetermined meshing length in the X-axis direction and with a gap G in the Y-axis direction.

[0024] The above is a brief description of the configuration of the vibration power generation element 1. In the vibration power generation element 1 configured as above, when a force is applied in the X-axis direction, the movable part 5 vibrates in the X-axis direction while elastically deforming the first and second spring parts 41 and 42. The vibration of the movable part 5 then changes the meshing lengths of the movable electrode fingers 61 and the first and second fixed electrode fingers 71 and 81 in opposite phases, thereby generating power. Note that in this embodiment, the electret film EL is formed on the movable electrode 6, but this is not limiting, and the electret film EL may be formed on the first and second fixed electrodes 7 and 8, or on both the movable electrode 6 and the first and second fixed electrodes 7 and 8.

[0025] As described above, in this vibration power generation element 1, the movable part 5 is formed from the first silicon layer 2A, and the movable electrode 6 and the first and second fixed electrodes 7 and 8 are formed from the second silicon layer 2C. This allows the movable part 5 and the electrodes 6, 7, and 8 to be arranged overlapping in the Z-axis direction. This allows the movable part 5 and the electrodes 6, 7, and 8 to be made large without increasing the planar dimensions of the vibration power generation element 1. By increasing the size of the movable part 5, the sensitivity of the vibration power generation element 1 is improved, allowing the movable part 5 to vibrate efficiently even in low frequency bands. Furthermore, by increasing the size of the electrodes 6, 7, and 8, the capacitance between the movable electrode 6 and the first and second fixed electrodes 7 and 8 can be increased. This results in a vibration power generation element 1 that is small in size and has excellent power generation characteristics.

[0026] In particular, the vibration power generation element 1 has excellent dimensional accuracy because it is formed by patterning a single SOI substrate 2, and can further reduce the gap G between the movable electrode finger 61 and the first and second fixed electrode fingers 71, 81 compared to the method described in Patent Document 2, which requires consideration of variations in the bonding of two substrates. This makes it possible to further increase the capacitance between the movable electrode 6 and the first and second fixed electrodes 7, 8. This further improves the power generation characteristics.

[0027] Next, we will explain the manufacturing method of the vibration power generation element 1. As shown in Fig. 4, the manufacturing method of the vibration power generation element 1 includes an SOI substrate preparation step S1 of preparing an SOI substrate 2, a second silicon layer patterning step S2 of patterning the second silicon layer 2C by etching to form the support portion 3, the movable electrode 6, and the first and second fixed electrodes 7 and 8 on the second silicon layer 2C, a first silicon layer patterning step S3 of patterning the first silicon layer 2A by etching to form the support portion 3, the spring portion 4, and the movable portion 5 on the first silicon layer 2A, a silicon oxide layer removal step S4 of removing a part of the silicon oxide layer 2B to separate the movable portion, and an electret film formation step S5 of forming an electret film on the movable electrode 6.

[0028] ≪SOI substrate preparation process S1≫ Step S1 is a step of preparing an SOI substrate 2 having a silicon oxide layer 2B inserted between first and second silicon layers 2A and 2C. In step S1, as shown in Fig. 9, an SOI substrate 2 is prepared in which the silicon oxide layer 2B has been removed from between a movable electrode forming region Q6 of the second silicon layer 2C where the movable electrode 6 is to be formed and a movable portion forming region Q5 of the first silicon layer 2A where the movable portion 5 is to be formed. This results in a configuration in which the silicon oxide layer 2B is not interposed between the movable electrode 6 and the movable portion 5, and they are structurally electrically connected. This simplifies the configuration of the vibration power generation element 1.

[0029] As shown in FIG. 4, this process S1 includes a first silicon layer preparation process S11 for preparing a first silicon layer 2A, a recess formation process S12 for forming a recess 21 on the upper surface of the first silicon layer 2A, a silicon oxide layer deposition process S13 for depositing a silicon oxide layer 2B on the upper surface of the first silicon layer 2A, a silicon oxide layer removal process S14 for removing the silicon oxide layer 2B while leaving the portion filling the recess 21, thereby exposing the upper surface, and a second silicon layer bonding process S15 for bonding a second silicon layer 2C to the upper surface of the first silicon layer 2A.

[0030] -First silicon layer preparation step S11- First, a first silicon layer 2A is prepared as shown in Fig. 5. The first silicon layer 2A is, for example, a silicon substrate with a thickness of about 400 µm.

[0031] - Recess formation process S12 - Next, as shown in Fig. 6, a recess 21 is formed on the upper surface of the first silicon layer 2A. The recess 21 is formed so as to exclude the area where the movable electrode forming region Q6 and the movable portion forming region Q5 overlap. The method for forming the recess 21 is not particularly limited, but RIE (reactive ion etching) can be used, for example. The thickness of the recess 21 is, for example, about 20 µm.

[0032] -Silicon oxide layer deposition process S13- Next, a silicon oxide layer 2B is formed on the upper surface of the first silicon layer 2A as shown in Fig. 7. The film formation method is not particularly limited, and may be, for example, thermal oxidation, CVD, or the like.

[0033] -Silicon oxide layer removal process S14- 8, the silicon oxide layer 2B is removed, leaving the portion filling the recess 21, to expose the upper surface of the first silicon layer 2A. The method for removing the silicon oxide layer 2B is not particularly limited, but for example, CMP (chemical mechanical polishing) can be used.

[0034] -Second silicon layer bonding process S15- Next, the second silicon layer 2C is prepared. The second silicon layer 2C is, for example, a silicon substrate with a thickness of about 300 μm. Next, as shown in FIG. 9, the second silicon layer 2C is bonded to the upper surface of the first silicon layer 2A.

[0035] The above steps result in the SOI substrate 2. This method makes it possible to easily manufacture the SOI substrate 2. However, the method for manufacturing the SOI substrate 2 is not particularly limited.

[0036] <<Second silicon layer patterning process S2>> Next, as shown in FIG. 10 , the second silicon layer 2C is etched from the top surface side to form through-holes that penetrate the second silicon layer 2C, thereby forming the support portion 3, the movable electrode 6, and the first and second fixed electrodes 7 and 8 on the second silicon layer 2C. At this time, the silicon oxide layer 2B functions as an etching stop layer. Dry etching, particularly reactive ion etching (RIE), can be used for the etching. By using dry etching, through-holes with a high aspect ratio can be formed with high precision, allowing the gap G to be designed to be smaller. This makes it possible to manufacture a vibration power generation element 1 with excellent power generation characteristics. However, the etching method is not particularly limited, and wet etching, for example, may also be used.

[0037] <First silicon layer patterning step S3> Next, as shown in FIG. 11, the first silicon layer 2A is etched from the bottom side to form through-holes that penetrate the first silicon layer 2A, thereby forming the support portion 3, the spring portion 4, and the movable portion 5 in the first silicon layer 2A (however, the spring portion 4 is not shown in FIG. 11). At this time, the silicon oxide layer 2B functions as an etching stop layer. For example, dry etching, particularly RIE (reactive ion etching), can be used for the etching. By using dry etching, through-holes with a high aspect ratio can be formed with high precision. However, the etching method is not particularly limited, and for example, wet etching may be used.

[0038] <Silicon oxide layer removal step S4> 12, a part of the silicon oxide layer 2B, specifically the part between the spring portion 4 and the movable portion 5 and the second silicon layer 2C, in other words, all parts except the support portion 3 are removed to make the spring portion 4 and the movable portion 5 movable relative to the support portion 3. However, as long as the spring portion 4 and the movable portion 5 can be made movable relative to the support portion 3, there is no particular limitation on the part of the silicon oxide layer 2B to be removed.

[0039] <Electret film formation process S5> Next, as shown in Fig. 13, an electret film EL is formed on the movable electrode 6, and terminals T1 and T2 are also formed (however, the terminals T1 and T2 are not shown in Fig. 13). The method for forming the electret film EL is not particularly limited, and any known method can be used. For example, there is a method in which a silicon oxide film is formed on the surface of the second silicon layer 2C by thermal oxidation, and then this silicon oxide film is doped with alkali metal ions such as potassium ions, and then an electric field is applied to charge it.

[0040] In this way, the vibration power generating element 1 is obtained. However, the manufacturing method of the vibration power generating element 1 is not particularly limited, and for example, the order of the second silicon layer patterning step S2 and the first silicon layer patterning step S3 may be reversed. In other words, the second silicon layer patterning step S2 may be performed after the first silicon layer patterning step S3. Furthermore, if etching from the top surface side and etching from the bottom surface side can be performed simultaneously, these steps may be performed simultaneously.

[0041] In this manufacturing method, the movable part 5 is formed from the first silicon layer 2A, and the movable electrode 6 and the first and second fixed electrodes 7 and 8 are formed from the second silicon layer 2C located above it. Therefore, the movable part 5 and the electrodes 6, 7, and 8 can be arranged overlapping in the Z-axis direction. Therefore, the movable part 5 and the electrodes 6, 7, and 8 can be made large without increasing the planar dimensions of the vibration power generation element 1. By increasing the size of the movable part 5, the sensitivity of the vibration power generation element 1 is improved, and the movable part 5 can be vibrated efficiently even in low frequency bands. Furthermore, by increasing the size of the electrodes 6, 7, and 8, the capacitance between the movable electrode 6 and the first and second fixed electrodes 7 and 8 can be increased. Therefore, a vibration power generation element 1 that is small and has excellent power generation characteristics can be manufactured.

[0042] In particular, the vibration power generation element 1 has excellent dimensional accuracy because it is formed by patterning a single SOI substrate 2, and compared to the method of Patent Document 2 described above, which requires consideration of variations in the bonding of two substrates, the gap G between the movable electrode finger 61 and the first and second fixed electrode fingers 71, 81 can be made smaller. This makes it possible to increase the capacitance between the movable electrode 6 and the first and second fixed electrodes 7, 8. This makes it possible to manufacture a vibration power generation element 1 with better power generation characteristics.

[0043] The above has described the vibration power generating element 1 and the manufacturing method of the vibration power generating element 1. The manufacturing method of the vibration power generating element 1 is a vibration device having a support part 3, a movable part 5 displaceable in the X-axis direction as a first direction relative to the support part 3, a movable electrode 6 connected to the movable part 5, and first and second fixed electrodes 7 and 8 as fixed electrodes connected to the support part 3 and arranged side by side in the Y-axis direction as a second direction perpendicular to the X-axis direction with respect to the movable electrode 6, and includes the steps of: SOI substrate preparation step S1 of preparing an SOI substrate 2 having a silicon oxide layer 2B interposed between a first silicon layer 2A and a second silicon layer 2C; The method includes a second silicon layer patterning step S2 in which the second silicon layer 2C is patterned by etching to form a support portion 3, a movable electrode 6, and first and second fixed electrodes 7, 8 on the second silicon layer 2C; a first silicon layer patterning step S3 in which the first silicon layer 2A is patterned by etching to form a support portion 3 and a movable portion 5 on the first silicon layer 2A; and a silicon oxide layer removal step S4 in which the silicon oxide layer 2B between the movable portion 5 and the second silicon layer 2C is removed to separate the movable portion 5 from the first and second fixed electrodes 7, 8.

[0044] In this manufacturing method, the movable part 5 is formed from the first silicon layer 2A, and the movable electrode 6 and the first and second fixed electrodes 7, 8 are formed from the second silicon layer 2C located above it. This allows the movable part 5 and the electrodes 6, 7, 8 to be arranged overlapping in the Z-axis direction. This means that the movable part 5 and the electrodes 6, 7, 8 can both be formed large without increasing the planar dimensions of the vibration power generation element 1. As a result, a small vibration power generation element 1 with excellent power generation characteristics can be manufactured.

[0045] In particular, the vibration power generation element 1 has excellent dimensional accuracy because it is formed by patterning a single SOI substrate 2, and compared to the method of Patent Document 2 described above, which requires consideration of variations in the bonding of two substrates, the gap G between the movable electrode finger 61 and the first and second fixed electrode fingers 71, 81 can be made smaller. This makes it possible to increase the capacitance between the movable electrode 6 and the first and second fixed electrodes 7, 8. This makes it possible to manufacture a vibration power generation element 1 with better power generation characteristics.

[0046] As described above, dry etching is used in the first silicon layer patterning step S3 and the second silicon layer patterning step S2. This allows the first silicon layer 2A and the second silicon layer 2C to be patterned with high precision. Furthermore, since holes with a high aspect ratio can be formed, the gap G can be made smaller, allowing the vibration power generation element 1 to be manufactured with better power generation characteristics.

[0047] As described above, the manufacturing method of the vibration power generating element 1 includes the electret film forming step S5, which is performed after the silicon oxide layer removing step S4, and in which the electret film EL is formed on at least one of the movable electrode 6 and the first and second fixed electrodes 7 and 8. This results in a vibration power generating element 1 that generates power by vibration of the movable part 5 in the X-axis direction.

[0048] As described above, in the SOI substrate preparation step S1, an SOI substrate 2 is prepared in which the silicon oxide layer 2B has been removed from between the movable electrode formation region Q6 of the second silicon layer 2C where the movable electrode 6 is to be formed and the movable part formation region Q5 of the first silicon layer 2A where the movable part 5 is to be formed. This makes it easy to obtain the movable electrode 6 electrically connected to the first silicon layer 2A. This results in a vibration power generation element 1 that can be easily electrically connected to the outside.

[0049] As described above, the SOI substrate preparation step S1 includes the steps of: a first silicon layer preparation step S11 for preparing a first silicon layer 2A; a recess formation step S12 for forming a recess 21 in the upper surface (one of the main surfaces) of the first silicon layer 2A, excluding the area where the movable electrode formation region Q6 and the movable portion formation region Q5 overlap; a silicon oxide layer formation step S13 for forming a silicon oxide layer 2B on the upper surface of the first silicon layer 2A; a silicon oxide layer removal step S14 for removing the silicon oxide layer 2B except for the portion filling the recess 21, thereby exposing the upper surface of the first silicon layer 2A; and a second silicon layer bonding step S15 for bonding a second silicon layer 2C to the upper surface of the first silicon layer 2A. This method allows the SOI substrate 2 to be easily manufactured.

[0050] As described above, the vibration power generation element 1 has spring portions 4 that elastically deform in the X-axis direction and connect the support portions 3 and the movable portion 5. The spring portions 4 are formed in the first silicon layer 2A together with the support portions 3 and the movable portion 5 in the first silicon layer patterning step S3. By forming the spring portions 4 from the first silicon layer 2A in this way, the spring portions 4 can be disposed near the center of gravity of the movable portion 5, and unnecessary displacement of the movable portion 5 can be suppressed.

[0051] As described above, the vibration power generation element 1 is made of an SOI substrate 2 with a silicon oxide layer 2B interposed between a first silicon layer 2A and a second silicon layer 2C, and has a support portion 3, a spring portion 4 connected to the support portion 3, a movable portion 5 connected to the support portion 3 via the spring portion 4 and displacing in the X-axis direction, which is a first direction, relative to the support portion 3 while elastically deforming the spring portion 4, a movable electrode 6 connected to the movable portion 5, and first and second fixed electrodes 7 and 8 as fixed electrodes connected to the support portion 3 and arranged side by side with the movable electrode 6 in the Y-axis direction, which is a second direction orthogonal to the X-axis direction. The support portion 3 is formed from a laminate of the first silicon layer 2A, the silicon oxide layer 2B, and the second silicon layer 2C, the movable portion 5 and the spring portion 4 are formed from the first silicon layer 2A, and the movable electrode 6 and the first and second fixed electrodes 7 and 8 are formed from the second silicon layer 2C.

[0052] In this configuration, the movable part 5 is formed from the first silicon layer 2A, and the movable electrode 6 and the first and second fixed electrodes 7, 8 are formed from the second silicon layer 2C located above it. This allows the movable part 5 and the electrodes 6, 7, 8 to be arranged overlapping in the Z-axis direction. This means that the movable part 5 and the electrodes 6, 7, 8 can both be made large without increasing the planar dimensions of the vibration power generation element 1. As a result, the vibration power generation element 1 is small and has excellent power generation characteristics.

[0053] In particular, the vibration power generation element 1 has excellent dimensional accuracy because it is formed by patterning a single SOI substrate 2, and compared to the method of Patent Document 2 described above, which requires consideration of variations in the bonding of two substrates, the gap G between the movable electrode finger 61 and the first and second fixed electrode fingers 71, 81 can be made smaller. This makes it possible to increase the capacitance between the movable electrode 6 and the first and second fixed electrodes 7, 8. This further improves the power generation characteristics.

[0054] The above describes the vibration device manufacturing method and vibration device of the present invention based on the illustrated embodiment, but the present invention is not limited to this, and the configuration of each part can be replaced with any configuration having a similar function. Furthermore, in the above embodiment, an example in which the vibration device is applied to a power-generating vibration element is described, but the vibration device is not limited to this. For example, the vibration device may be applied to an inertial sensor that detects acceleration or angular velocity based on changes in capacitance between the movable electrode 6 and the first and second fixed electrodes 7 and 8.

[0055] 14, for example, a weight M may be placed on the underside of the movable part 5. This further increases the mass of the movable part 5, further improving the sensitivity of the vibration power generation element 1. In particular, with the vibration power generation element 1, a large area can be secured for the movable part 5, allowing a correspondingly larger weight M to be placed thereon. This further improves the above-mentioned effects. [Explanation of symbols]

[0056] 1...Vibration power generating element, 2...SOI substrate, 2A...first silicon layer, 2B...silicon oxide layer, 2C...second silicon layer, 21...recess, 3...support portion, 31...first fixed electrode connection area, 32...second fixed electrode connection area, 4...spring portion, 41...first spring portion, 42...second spring portion, 5...movable portion, 6...movable electrode, 61...movable electrode finger, 61A...movable electrode finger group, 61B...movable electrode finger group, 61C...movable electrode finger group, 7...first fixed electrode, 71...first fixed electrode finger, 71A...first fixed electrode finger group, 71B...first fixed electrode finger group, 71C...first fixed electrode finger group, 8...second fixed electrode, 81...second fixed electrode finger, 8 1A...second fixed electrode finger group, 81B...second fixed electrode finger group, 81C...second fixed electrode finger group, EL...electret film, G...gap, M...weight, Q5...movable portion forming region, Q6...movable electrode forming region, S1...SOI substrate preparation step, S11...first silicon layer preparation step, S12...recess formation step, S13...silicon oxide layer deposition step, S14...silicon oxide layer removal step, S15...second silicon layer bonding step, S2...second silicon layer patterning step, S3...first silicon layer patterning step, S4...silicon oxide layer removal step, S5...electret film formation step, T1...terminal, T2...terminal

Claims

1. A support part; a movable portion displaceable in a first direction relative to the support portion; a movable electrode connected to the movable portion; a fixed electrode connected to the support portion and arranged side by side with the movable electrode in a second direction perpendicular to the first direction; a spring portion that elastically deforms in the first direction and connects the support portion and the movable portion, When viewed from the first direction, the support portion, the movable portion, and the spring portion overlap each other, an SOI substrate preparation step of preparing an SOI substrate including a first silicon layer, a second silicon layer, and a silicon oxide layer interposed between the first silicon layer and the second silicon layer; a second silicon layer patterning step of patterning the second silicon layer by etching to form the support portion, the movable electrode, and the fixed electrode in the second silicon layer; a first silicon layer patterning step of patterning the first silicon layer by etching to form the support portion, the movable portion, and the spring portion in the first silicon layer; A method for manufacturing a vibration device, comprising: a silicon oxide layer removal process for removing the silicon oxide layer between the movable portion and the second silicon layer to separate the movable portion from the fixed electrode.

2. The method for manufacturing a resonator device according to claim 1 , wherein dry etching is used as the etching in each of the first silicon layer patterning step and the second silicon layer patterning step.

3. The method for manufacturing a vibration device according to claim 1 or 2, further comprising an electret film forming step, which is performed after the silicon oxide layer removing step, and which forms an electret film on at least one of the movable electrode and the fixed electrode.

4. 4. A method for manufacturing a vibration device according to claim 1, wherein the SOI substrate preparation process includes preparing the SOI substrate from which the silicon oxide layer has been removed between a movable electrode formation region of the second silicon layer in which the movable electrode is formed and a movable part formation region of the first silicon layer in which the movable part is formed.

5. The SOI substrate preparation step includes: a first silicon layer preparation step of preparing the first silicon layer; a recess forming step of forming a recess in one main surface of the first silicon layer excluding a region where the movable electrode forming region and the movable portion forming region overlap; a silicon oxide layer forming step of forming the silicon oxide layer on the main surface of the first silicon layer; a silicon oxide layer removing step of removing the silicon oxide layer while leaving the portion filled in the recess, thereby exposing the main surface; The method for manufacturing a resonation device according to claim 4 , further comprising: a second silicon layer bonding step of bonding the second silicon layer to the main surface.

6. an SOI substrate including a first silicon layer, a second silicon layer, and a silicon oxide layer interposed between the first silicon layer and the second silicon layer; A support part; a spring portion connected to the support portion; a movable portion connected to the support portion via the spring portion and displaced in a first direction relative to the support portion while elastically deforming the spring portion; a movable electrode connected to the movable portion; a fixed electrode connected to the support portion and arranged next to the movable electrode in a second direction perpendicular to the first direction, the support portion is formed from a stack of the first silicon layer, the silicon oxide layer, and the second silicon layer; the movable portion and the spring portion are formed from the first silicon layer; the movable electrode and the fixed electrode are formed from the second silicon layer; A vibration device characterized in that the support portion, the movable portion, and the spring portion overlap when viewed from the first direction.

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