Method for manufacturing a curved support structure, hemispherical resonator gyroscope

Abstract

This method includes: a supporting portion forming step of performing etching to form an annular recessed portion on an upper surface of a lower wafer, and etching a radially outer surface, which is a flat surface on the radially outer side of the recessed portion, to form a supporting portion having an apex higher than the radially outer surface, in a substantially central portion of the recessed portion; a first electrode forming step of forming a plurality of first electrodes disposed on the radially outer surface; a sacrificial layer coating step of forming an annular coating pattern on the plurality of first electrodes, as a sacrificial layer; a second electrode forming step of forming, on a bottom surface of an upper wafer, a plurality of second electrodes disposed to correspond to the plurality of first electrodes; a bonding step of bonding the upper wafer and the lower wafer, sandwiching the sacrificial layer, such that the plurality of first electrodes and the plurality of second electrodes overlap one another; a radially outer portion separating step of performing etching to separate a radially outer portion of the upper wafer positioned on the radially outer side of the second electrodes; a different-pressure heating step of vacuum-heating the upper wafer, the lower wafer, and the sacrificial layer, with a cavity pressure and an atmospheric pressure set to differ from one another; and a sacrificial layer removing step of performing etching to remove the sacrificial layer.

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to a curved support structure that can be utilized as a hemispherical resonator gyroscope. [Background technology]

[0002] Hemispherical resonator gyroscopes have been known as gyroscopes for detecting angular velocity. As shown in Figures 19 and 20, this type of hemispherical resonator gyroscope 9 includes a resonator 91 formed in a generally hemispherical shape as a whole, a support 90 that supports the resonator 91, a plurality of electrodes 92 formed on the outside of the resonator 91 and arranged in a ring shape, and a plurality of electrodes 93 formed on the inside of the resonator 91 and arranged in a ring shape.

[0003] The hemispherical resonator gyroscope 9 uses multiple electrodes 92 or multiple electrodes 93, alternately arranged in the circumferential direction, as either detection electrodes 92A, 93A or control electrodes 92B, 93B. When a braking voltage is applied to the control electrodes 92B, 93B, the resonator 91 resonates due to electrostatic attraction. When an angular velocity is input in this state, the resonant shape of the resonator 91 rotates in accordance with the angular velocity, and the capacitance between the resonator 91 and the detection electrodes 92A, 93A is detected, thereby determining the angular velocity. Note that multiple electrodes 94 (see FIG. 20) formed in a ring shape below the resonator 91 can also be used as detection electrodes or drive electrodes.

[0004] In such hemispherical resonator gyroscopes, the performance is determined by the Q value of the resonator and the positional relationship of the electrodes. To increase the Q value of the resonator and reduce noise and improve performance, quartz or synthetic glass, which have a low thermoelastic coefficient, are used for the resonator. In this case, the resonator is formed by processing quartz or synthetic glass, both of which are difficult to process and require high processing precision. Therefore, forming such a resonator requires mechanical polishing and cutting, followed by final shape adjustment using laser processing, which significantly increases manufacturing costs.

[0005] In order to reduce the manufacturing cost of resonators, a manufacturing method that applies the MEMS (Micro Electro Mechanical Systems) process has been proposed. One known manufacturing method of this type is to process a quartz wafer into a shape known as a wine glass or birdbath by heating it to a temperature at which it can be deformed and then applying suction or pressure.

[0006] However, this method requires laser cutting and polishing to separate the resonators, and also requires the resonators to be attached to a substrate with electrodes using adhesive or other means. This tends to result in poor alignment accuracy for semiconductor devices used in general MEMS processes, degrading the performance of the manufactured hemispherical resonator gyroscope. Furthermore, this method does not involve batch processing, which increases the manufacturing cost of the hemispherical resonator gyroscope. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-148659 [Patent Document 2] U.S. Patent No. 6,474,161 [Patent Document 3] U.S. Patent No. 7,839,059 [Patent Document 4] U.S. Patent No. 10,612,925 [Non-patent literature]

[0008] [Non-Patent Document 1] D. Senkal, CR Raum, AA Trusov, AM Shkel, “TITANIA SILICATE / FUSED QUARTZ GLASSBLOWING FOR 3-D FABRICATION OF LOW INTERNAL LOSS WINEGLASS MICRO-STRUCTURES”, Solid-State, Actuators, and Microsystems Workshop, 2012, DOI: 10.31438 / trf.hh2012.72 [Non-patent document 2] P. Pai, FK Chowdhury, CH Mastrangelo and M. Tabib-Azar, "MEMS-based hemispherical resonator gyroscopes," SENSORS, 2012 IEEE, Taipei, Taiwan, 2012, pp. 1-4, doi: 10.1109 / ICSENS.2012.6411346. [Non-patent document 3] D. Senkal, MJ Ahamed, MHA Ardakani, S. Askari and AM Shkel, "Demonstration of 1 Million Q -Factor on Microglassblown Wineglass Resonators With Out-of-Plane Electrostatic Transduction," in Journal of Microelectromechanical Systems, vol. 24, no. 1, pp. 29-37, Feb. 2015, doi: 10.1109 / JMEMS.2014.2365113. Summary of the Invention [Problem to be solved by the invention]

[0009] The problem that embodiments of the present invention attempt to solve is to provide a technique that can manufacture a curved support structure that can be used as a hemispherical resonator gyroscope at a lower cost. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the manufacturing method of a curved support structure according to this embodiment is a manufacturing method of a curved support structure composed of an upper wafer and a lower wafer, and includes a support part forming step of forming an annular recess on the upper surface of the lower wafer by etching, and etching the radially outer surface, which is the flat surface on the radially outer side of the recess, to form a support part having an apex higher than the radially outer surface in approximately the center of the recess; a first electrode forming step of forming a plurality of first electrodes arranged in a ring shape on the radially outer surface; a sacrificial layer applying step of forming a ring shape applied pattern on the plurality of first electrodes as a sacrificial layer; and a plurality of second electrodes arranged in a ring shape corresponding to the plurality of first electrodes on the bottom surface of the upper wafer. a bonding process of bonding the upper wafer and the lower wafer together with the sacrificial layer sandwiched therebetween so that the plurality of first electrodes and the plurality of second electrodes overlap; a radial outer separation process of separating, after the bonding process, a radial outer portion of the upper wafer located radially outer than the second electrodes by etching; a differential pressure heating process of vacuum-heating the upper wafer, the lower wafer, and the sacrificial layer by differentiating the pressure in a cavity defined by the upper wafer, the lower wafer, and the sacrificial layer from the atmospheric pressure after the differential pressure heating process; and a sacrificial layer removal process of removing the sacrificial layer by etching after the differential pressure heating process. [Effects of the Invention]

[0011] According to embodiments of the present invention, a curved support structure that can be used as a hemispherical resonator gyroscope can be manufactured at a lower cost. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a flowchart illustrating a method for manufacturing a curved support structure according to an embodiment. [Figure 2]FIG. 2 is a plan view showing the configuration of a lower wafer in which a recess is formed. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 2 is a plan view showing the configuration of a lower wafer on which electrodes are formed. [Figure 5] FIG. 5 is a cross-sectional view taken along line BB in FIG. 4. [Figure 6] FIG. 2 is a plan view showing the configuration of a lower wafer on which a sacrificial layer is formed. [Figure 7] FIG. 7 is a cross-sectional view taken along line CC in FIG. 6. [Figure 8] FIG. 2 is a bottom view showing the configuration of an upper wafer on which electrodes are formed. [Figure 9] FIG. 9 is a cross-sectional view taken along the line DD in FIG. 8. [Figure 10] FIG. 2 is a plan view showing the upper wafer and the lower wafer bonded together. [Figure 11] FIG. 11 is a cross-sectional view taken along the line EE in FIG. [Figure 12] FIG. 10 is a side cross-sectional view showing the upper wafer from which the outer diameter portion has been separated. [Figure 13] 10 is a side cross-sectional view showing the upper and lower wafers vacuum-heated in a state where the pressure inside the chamber is lower than that of the sealed space; FIG. [Figure 14] FIG. 2 is a side cross-sectional view showing the configuration of a curved support structure having an annular convex curved surface. [Figure 15] FIG. 2 is a cross-sectional perspective view showing the configuration of a curved support structure having an annular convex curved surface. [Figure 16] 10 is a side cross-sectional view showing the upper and lower wafers vacuum-heated in a state where the pressure inside the chamber is greater than the sealed space; FIG. [Figure 17] FIG. 2 is a side cross-sectional view showing the configuration of a curved support structure having an annular concave curved surface. [Figure 18] FIG. 2 is a cross-sectional perspective view showing the configuration of a curved support structure having an annular concave curved surface. [Figure 19] FIG. 1 is a schematic plan view showing the configuration of a conventional hemispherical resonator gyroscope. [Figure 20] FIG. 1 is a side cross-sectional view showing the configuration of a conventional hemispherical resonator gyroscope. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] (Method of manufacturing a curved support structure) A method for manufacturing a curved support structure according to an embodiment will be described briefly below. Fig. 1 is a flowchart showing the method for manufacturing a curved support structure according to the present embodiment. Details of each step will be described later.

[0015] 1, first, a support forming process is performed on the lower wafer to form support parts for supporting the curved surface by etching (S101), a first electrode forming process is performed to form first electrodes (S102), and a sacrificial layer applying process is performed to apply and pattern a sacrificial layer (S103).Furthermore, a second electrode forming process is performed on the upper wafer to form second electrodes (S104).

[0016] After the sacrificial layer application process and the second electrode formation process are performed, a bonding process is performed in which the upper wafer and the lower wafer are bonded together using the sacrificial layer (S105), and a radial outer separation process is performed in which the radial outer portion of the upper wafer is separated (S106).

[0017] After the radial / external separation process, an isobaric heating process (S107) and a heterobaric heating process (S108) are carried out in which vacuum heating is performed using a vacuum heating device equipped with a chamber, and a sacrificial layer removal process (S109) is carried out in which the sacrificial layer is removed, thereby manufacturing a curved support structure that can be used as a hemispherical resonator gyroscope.

[0018] (Support part formation process) The support portion forming step will be described below. Fig. 2 is a plan view showing the configuration of the lower wafer in which recesses are formed. Fig. 3 is a cross-sectional view taken along line AA in Fig. 2.

[0019] The support portion forming step is a step of forming a support portion 11 by forming an annular recess 10 in the lower wafer 1, as shown in Figures 2 and 3. The lower wafer 1 is a plate-like member manufactured from a silicon compound such as synthetic quartz, silicon, tempax glass, or low-expansion glass. In the support portion forming step, the recess 10 is formed on its upper surface by isotropic etching, and a radial outer surface 12, which is a flat surface lower in height than the apex of the support portion 11, is formed radially outside the recess 10 by etching. The height difference between the apex of the support portion 11 and the radial outer surface 12 will be described in detail later.

[0020] (First electrode formation process) The first electrode forming step will be described below. Fig. 4 is a plan view showing the configuration of the lower wafer on which the electrodes are formed. Fig. 5 is a cross-sectional view taken along line BB in Fig. 4.

[0021] 4 and 5, the first electrode formation step is a step of forming a plurality of first electrodes 13 made of a high-melting point metal on the radially outer surface 12 of the lower wafer 1. The plurality of first electrodes 13 are formed on the radially outer surface 12 so as to be arranged side by side in an annular shape so as to surround the recess 10. Each of the plurality of first electrodes 13 has a connection line 131 extending radially outward.

[0022] (Sacrificial layer application process) The sacrificial layer application step will now be described. Fig. 6 is a plan view showing the configuration of the lower wafer on which the sacrificial layer is formed. Fig. 7 is a cross-sectional view taken along line CC in Fig. 6.

[0023] 6 and 7, the sacrificial layer application process is a process of forming a circular application pattern 3 as a sacrificial layer using liquid glass such as TEOS (Tetraethyl Orthosilicate Tetraethoxysilane) or polysilazane to cover a plurality of first electrodes 13. This application pattern is maintained in a semi-solid state until the bonding process described later.

[0024] (Second electrode formation process) The second electrode forming step will be described below. Fig. 8 is a bottom view showing the structure of the upper wafer on which the electrode is formed. Fig. 9 is a cross-sectional view taken along line DD in Fig. 8.

[0025] The second electrode forming step is a step of forming a plurality of second electrodes 23 on the upper wafer 2, as shown in FIGS. 8 and 9. Like the lower wafer 1, the upper wafer 2 is a plate-like member made of a silicon compound such as synthetic quartz, silicon, tempax glass, or low-expansion glass. In the second electrode forming step, a plurality of second electrodes 23 corresponding to the plurality of first electrodes 13 are formed on the bottom surface of the upper wafer 2. Here, the plurality of second electrodes 23 are formed so as to be arranged side by side in a ring shape, similar to the plurality of first electrodes 13.

[0026] In addition, in this embodiment, each of the multiple second electrodes 23 is formed small enough to fit within the area of ​​the corresponding first electrode 13 when superimposed on the corresponding first electrode 13, but the first electrode 13 may be formed smaller than the second electrode 23. By forming one of the first electrode 13 or the second electrode 23 to fit within the area of ​​the other in this way, it is possible to reduce the influence of misalignment that may occur in the bonding process.

[0027] Furthermore, in the support portion forming step, the radially outer surface 12 is etched so that the distance between the apex of the support portion 11 and the radially outer surface 12 is greater than the combined distance of the thickness of the first electrode 13 and the thickness of the second electrode 23. This forms a gap between the first electrode 13 and the second electrode 23 that are stacked in a bonding step described in detail later.

[0028] (Laminating process) The bonding step will be described below. Fig. 10 is a plan view showing the upper and lower wafers bonded together. Fig. 11 is a cross-sectional view taken along line EE in Fig. 10.

[0029] 10 and 11, the bonding process is a process of bonding the bottom surface of the upper wafer 2 and the top surface of the lower wafer 1 so that the plurality of first electrodes 13 and the corresponding plurality of second electrodes 23 overlap. In this bonding process, the upper wafer 2 and the lower wafer are aligned using a double-sided aligner, fixed by applying pressure, and then pre-baked using a vacuum heating device at 300 to 500°C in an atmosphere of a predetermined cavity pressure P1, thereby bonding the upper wafer 2 and the lower wafer 1 together. At this time, the cavity pressure, which is the pressure within the annular cavity C defined by the recess 10 in the lower wafer 1, the support portion 11, the bottom surface of the upper wafer 2, and the coating pattern 3, becomes P1.

[0030] If the upper wafer 2 and the lower wafer 1 are made of Tempax glass or silicon, an anodic bonding apparatus may be used instead of a double-sided aligner to bond the upper wafer 2 and the lower wafer 1. Whichever method is used, this bonding process can suppress alignment errors to the semiconductor process level (5 μm or less).

[0031] (diameter external separation process) The outer diameter separation step will now be described. Fig. 12 is a side cross-sectional view showing the upper wafer from which the outer diameter has been separated. Fig. 12 shows a cross section corresponding to Figs. 3, 5, 7, and 11, and shows a cut surface along a plane extending in the vertical and horizontal directions in the figure and passing through the support portion.

[0032] 12, the radial outer separation step is a step of separating the radial outer portion of the upper wafer 2 by etching. Here, the radial outer portion refers to the portion of the upper wafer 2 that is located radially outward of the coating pattern 3 when the center of the support portion 11 is taken as the center of a circle.

[0033] According to the differential pressure heating process, the upper wafer 2 is deformed into a three-dimensional shape, as will be described in detail later. However, by etching the planar upper wafer 2 prior to the differential pressure heating process, it is possible to apply precise patterns from semiconductor processes and to eliminate the need for costly laser cutting and polishing processes.

[0034] Although etching may result in portions at the edges of the upper wafer 2 that are formed at acute angles, these edges are rounded by heating in the isobaric heating process and the differential pressure heating process. As a result, when a curved support structure manufactured by this manufacturing method is used as a hemispherical resonator gyroscope, the energy trapping effect is enhanced, improving the Q value.

[0035] (Isobaric heating process and heterobaric heating process) The isobaric heating process and the differential pressure heating process will now be described. Figures 13 and 16 are cross-sectional side views showing the upper and lower wafers vacuum-heated in a state where the pressure in the chamber is lower than that of the sealed space and higher than that of the sealed space, respectively. Note that Figures 13 and 16 show cross sections cut along the same plane as Figure 12.

[0036] The isobaric heating process is a process in which the upper wafer 2 and the lower wafer 1 are vacuum-heated until they soften, with the atmospheric pressure P2, which is the pressure inside the chamber of the vacuum device, being approximately equal to the cavity pressure P1. In the isobaric heating process, the temperature inside the chamber is 1200 to 1400°C if the upper wafer 2 and the lower wafer 1 are made of quartz, and 500 to 600°C if they are made of Tempax glass. The isobaric heating process fuses the support portion 11 of the lower wafer 1 and the upper wafer 2 into a single unit, and fuses the coating pattern 3 made of liquid glass to the lower wafer 1 and the upper wafer 2, thereby improving the airtightness of the cavity C. Note that the fusion between the lower wafer 1 and the upper wafer 2 and the fusion between the coating pattern 3 and the lower wafer 1 and the upper wafer 2 also occurs in the differential pressure heating process, so the isobaric heating process can be omitted from this manufacturing method.

[0037] The differential pressure heating process is a process in which the ambient pressure P2 is made different from the cavity pressure P1, that is, the ambient pressure P2 is made lower than the cavity pressure P1 or the ambient pressure P2 is made higher than the cavity pressure P1, and the upper wafer 2 and the lower wafer 1 are vacuum heated until they are softened. In the differential pressure heating process, the temperature inside the chamber is 1400 to 1700°C when the upper wafer 2 and the lower wafer 1 are made of quartz, and 600 to 700°C when they are made of Tempax glass.

[0038] When the ambient pressure P2 is made lower than the cavity pressure P1 in the differential pressure heating process, the cavity C expands, deforming a portion of the upper wafer 2 and forming an annular convex curved surface 21A that is a curved surface that protrudes upward along a ring, as shown in Fig. 13. Furthermore, the portion of the upper wafer 2 that is fused to the annular coating pattern 3 does not deform, and a flange portion 22 that protrudes radially outward from the end of the annular convex curved surface 21A is formed.

[0039] On the other hand, if the ambient pressure P2 is made higher than the cavity pressure P1 in the differential pressure heating process, the cavity C contracts, causing a portion of the upper wafer 2 to deform, forming an annular concave surface 21B that is a curved surface that protrudes downward along an annular shape, as shown in Fig. 16. Furthermore, as in the case where the annular convex surface 21A is formed, the portion of the upper wafer 2 that is fused to the annular coating pattern 3 does not deform, and a flange portion 22 that protrudes radially outward from the end of the annular concave surface 21B is formed.

[0040] In either a differential pressure heating process in which the ambient pressure P2 is set lower than the cavity pressure P1, or a differential pressure heating process in which the ambient pressure P2 is set higher than the cavity pressure P1, the thickness, height, curvature, etc. of the annular convex curved surface 21A and the annular concave curved surface 21B can be made as desired by adjusting the pressure difference between the cavity pressure P1 and the ambient pressure P2, the temperature in the chamber during vacuum heating, the lifting time of the lifting mechanism in the vacuum heating device, etc.

[0041] Furthermore, in the differential pressure heating process, the liquid glass that forms the coating pattern 3 has a composition closer to that of quartz, which improves the airtightness within the cavity C, but results in poor chemical resistance compared to the materials of the upper wafer 2 and the lower wafer 1.

[0042] (Sacrificial layer removal process) The sacrificial layer removal process will now be described. Figures 14 and 15 are a side cross-sectional view and a cross-sectional perspective view, respectively, showing the configuration of a curved support structure having an annular convex curved surface. Figures 17 and 18 are a side cross-sectional view and a cross-sectional perspective view, respectively, showing the configuration of a curved support structure having an annular concave curved surface. Note that Figures 14, 15, 17, and 18 all show cross sections cut along the same plane as Figures 12 and 13.

[0043] The sacrificial layer removal process is a process of removing the coating pattern 3 formed from liquid glass by etching. The coating pattern 3 denatured by vacuum heating has a faster etch rate than other parts, so it can be selectively removed by etching. Note that in the sacrificial layer removal process, a chemical that etches only the liquid glass that forms the coating pattern 3 may be used.

[0044] The sacrificial layer removal process produces a curved support structure 4A having an upwardly protruding annular convex surface 21A as shown in Figures 14 and 15, or a curved support structure 4B having a downwardly protruding annular concave surface 21B as shown in Figures 17 and 18. The curved support structure 4A includes the annular convex surface 21A, a flange portion 22, a support portion 11 that supports the annular convex surface 21A at a substantially central position, a first electrode 13, and a second electrode 23. The curved support structure 4B differs from the curved support structure 4A only in that it includes an annular concave surface 21B instead of the annular convex surface 21A.

[0045] According to the manufacturing method described above, it is possible to manufacture curved support structures 4A, 4B that can be used as a hemispherical resonator gyroscope using existing inexpensive processes. Furthermore, according to this manufacturing method, the three-dimensional annular convex curved surface 21A, the annular concave curved surface 21B, and the support portion 11 are formed simultaneously with the first electrode 13 and the second electrode 23. This eliminates the need for mechanical alignment during the manufacturing process, and also prevents performance degradation due to the effects of misalignment, such as drift, when the curved support structures 4A, 4B are used as a hemispherical resonator gyroscope.

[0046] In this embodiment, the multiple first electrodes 13 and the multiple second electrodes 23 are described as being arranged side by side in a ring shape, but the multiple first electrodes 13 may be arranged on the outer radial surface 12, and the multiple second electrodes 23 may be arranged on the bottom surface of the upper wafer 2 corresponding to the multiple first electrodes 13.

[0047] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0048] 1 Lower wafer 2 Upper wafer 3 Application pattern 4A,4B Curved support structure 10 recess 11 Support part 12 diameter outer surface 13 1st electrode 23 2nd electrode 21A Annular convex surface 21B Annular concave surface 22 Flange

Claims

1. A method for manufacturing a curved support structure composed of an upper wafer and a lower wafer, a support portion forming step of forming an annular recess on the upper surface of the lower wafer by etching, and etching a radially outer surface, which is a flat surface on the radially outer side of the recess, to form a support portion having an apex higher than the radially outer surface at approximately the center of the recess; a first electrode forming step of forming a plurality of first electrodes disposed on the radially outer surface; a sacrificial layer coating step of forming a circular coating pattern as a sacrificial layer on the plurality of first electrodes; a second electrode forming step of forming a plurality of second electrodes on the bottom surface of the upper wafer, the second electrodes being arranged corresponding to the plurality of first electrodes; a bonding step of bonding the upper wafer and the lower wafer together with the sacrificial layer sandwiched therebetween so that the plurality of first electrodes and the plurality of second electrodes overlap; a radial outer separation step of separating a radial outer portion of the upper wafer located radially outer than the second electrode by etching after the bonding step; a differential pressure heating step of vacuum-heating the upper wafer, the lower wafer, and the sacrificial layer by making a pressure in a cavity defined by the upper wafer, the lower wafer, and the sacrificial layer different from an atmospheric pressure after the radial separation step; a sacrificial layer removal step of removing the sacrificial layer by etching after the differential pressure heating step; A method for manufacturing a curved support structure comprising:

2. 2. The method for manufacturing a curved support structure according to claim 1, further comprising, after the radial external separation process and prior to the differential pressure heating process, an isobaric heating process in which the pressure inside the cavity is made equal to the atmospheric pressure and the upper wafer, the lower wafer, and the sacrificial layer are vacuum heated.

3. the upper wafer and the lower wafer are made of a silicon compound; 3. The method for manufacturing a curved support structure according to claim 1, wherein the coating pattern is formed from liquid glass.

4. The method for manufacturing a curved support structure according to any one of claims 1 to 3, characterized in that the differential pressure heating step performs vacuum heating by making the atmospheric pressure lower than the pressure inside the cavity.

5. The method for manufacturing a curved support structure according to any one of claims 1 to 3, characterized in that the differential pressure heating step performs vacuum heating by making the atmospheric pressure higher than the pressure inside the cavity.

6. The plurality of first electrodes are arranged side by side in an annular shape on the radially outer surface, A method for manufacturing a curved support structure described in any one of claims 1 to 5, characterized in that the plurality of second electrodes are arranged in a ring shape on the bottom surface of the upper wafer corresponding to the plurality of first electrodes.

7. A curved surface portion formed as an annular convex curved surface projecting upward or an annular concave curved surface projecting downward; a curved surface support structure having a downwardly protruding annular recess and a support portion that supports the curved surface portion from above at an approximate circular center of the recess; a flange portion formed at a radially outer end of the curved surface portion so as to extend radially outward beyond the recess; a first electrode formed radially outward of the recess in the curved support structure; a second electrode formed on the flange portion so as to face the first electrode; A hemispherical resonator gyroscope comprising:

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