Method for manufacturing a curved support structure

Abstract

A structure in which an electrode pattern connecting an electrode on a resonator side to an electrode on a support portion side is formed on the resonator; according to the present application, there is provided a manufacturing method of a curved surface support structure body, including: a step (a) of preparing a first wafer having a first electrode pattern including a first electrode; a step (b) of obtaining a laminate having a ring belt-shaped cavity inside by joining the first wafer with a second wafer having a second electrode pattern including a plurality of second electrodes; a step (c) of deforming a surface of at least one of the first wafer and the second wafer into a curved surface shape by a pressure difference between the cavity and the outside of the laminate by heating, thereby increasing or decreasing the cavity volume; and a step (d) of removing a part of the first wafer along a circumference concentric with the ring belt, thereby forming a resonator whose center portion is supported by the second wafer from the first wafer; the step (a) includes a step (a1) of obtaining the first wafer by forming the first electrode pattern on one side main surface of a bare wafer, in the step (b), the first electrode and the second electrode in the laminate are opposed to each other with a pitch, and the step (b) includes a step of electrically connecting the first electrode and the second electrode pattern of the second wafer.

Description

Technical Field

[0001] This invention relates to a method for manufacturing curved surface support structures. Background Technology

[0002] Gyroscopes are widely used to detect changes in the attitude of objects. Among them, vibrating gyroscopes (VSG, also known as Coriolis vibratory gyroscope (CVG)) have attracted much attention due to their robustness, small size, and ability to achieve high precision. For example, Patent Document 1 below discloses a hemispherical resonant gyroscope (HRG) having a resonator with an upwardly convex shape and a support portion supporting the resonator.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2022 / 224704 Summary of the Invention

[0006] Patent Document 1 describes a hemispherical resonator gyroscope with the following structure: multiple electrodes on the resonator side and multiple electrodes on the support side are placed opposite each other with a predetermined gap. The hemispherical resonator gyroscope detects the applied angular velocity change by measuring the change in electrostatic capacitance between the opposing electrodes, which manifests as a change in the position of the resonator's vibration node. Based on this detection principle, when the gyroscope is operating, the electrode potential on the resonator side is typically not at a floating potential, but fixed at a predetermined potential (typically ground potential). The resonator needs to have an electrical connection from the electrodes on the resonator side to a power supply or the like on the support side.

[0007] According to the present invention, the following invention is provided.

[0008] [1] A method for manufacturing a curved support structure includes: a step (a) preparing a first wafer having a first electrode pattern including a first electrode; a step (b) obtaining a laminate having an annular cavity inside by joining the first wafer with a second wafer having a second electrode pattern including a plurality of second electrodes; a step (c) increasing or decreasing the cavity volume by heating and utilizing the pressure difference between the cavity and the outside of the laminate to deform the surface of at least one of the first wafer and the second wafer into a curved shape. The steps (d) include removing a portion of the first wafer along a circumference concentric with the annular band, forming a resonator whose central portion is supported by the second wafer from the first wafer, wherein step (a) includes step (a1) of obtaining the first wafer by forming the first electrode pattern on a main side of a bare wafer, wherein in step (b), the first electrode and the second electrode in the stack are spaced apart and face each other, and step (b) includes step of electrically connecting the first electrode to the second electrode pattern of the second wafer.

[0009] [2] The manufacturing method as described in [1], wherein step (a1) includes the step of forming a bottom layer as the first electrode pattern or a conductive layer as the first electrode pattern by sputtering.

[0010] [3] The manufacturing method as described in [1] or [2], wherein step (a) further includes step (a2) of forming an annular recess on the main surface of the bare wafer prior to step (a1), wherein in step (a1), the first electrode pattern extends beyond the outer edge of the recess from the interior of the recess to the exterior of the recess.

[0011] [4] The manufacturing method as described in any one of [1] to [3], wherein, in step (c), the pressure inside the cavity is above 0.1 standard atmospheres and below 0.5 standard atmospheres.

[0012] [5] The manufacturing method as described in [4], wherein step (b) includes bonding the first wafer and the second wafer under reduced pressure.

[0013] [6] The manufacturing method of any one of [1] to [5], wherein, between step (b) and step (c), a step (e) is further included in which a fixture having a hole with a rounded opening is disposed on another main surface of the first wafer, and step (c) includes a step of deforming a portion of the other main surface of the first wafer into a shape conforming to the shape of the opening of the fixture.

[0014] [7] The manufacturing method as described in [6], wherein the fixture has a protrusion located at the center of the hole, the protrusion having a front end with rounded corners.

[0015] [8] The manufacturing method of any one of [1] to [7], wherein the resonator comprises: a columnar portion extending upward from the second wafer; and an edge portion arranged in a ring around the columnar portion.

[0016] According to at least any embodiment of the present invention, a structure in which an electrode pattern connecting the electrode on the resonator side to the electrode pattern on the support side can be efficiently formed on the resonator. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating an exemplary manufacturing method of a hemispherical resonator gyroscope according to a certain embodiment of the present invention.

[0018] Figure 2 It is a schematic vertical cross-sectional view of the first wafer with the first electrode pattern.

[0019] Figure 3 This is a schematic top view showing an example of the pattern of the first electrode.

[0020] Figure 4 This is a diagram showing, enlarged and schematically illustrated, an example of a cross-section of the first electrode pattern PA.

[0021] Figure 5 This is a schematic vertical cross-sectional view of a bare wafer with a recess formed on one side of its main face.

[0022] Figure 6 This is a schematic top view used to illustrate the typical shape of a recess formed on a bare wafer.

[0023] Figure 7 This is a schematic vertical cross-sectional view of the bare wafer 20 after the second electrode pattern has been formed.

[0024] Figure 8 This is a schematic top view showing an example of the second electrode pattern.

[0025] Figure 9 This is a schematic top view showing another example of the shape of the second electrode pattern PB.

[0026] Figure 10 This is a schematic diagram showing a vertical cross-section of the laminate 30A obtained by joining the upper wafer 10WA and the lower wafer 20WA.

[0027] Figure 11 This is a schematic diagram illustrating an example of the overlap between the first electrode pattern PA and the second electrode pattern PB in the laminate 30A.

[0028] Figure 12 This is a schematic diagram illustrating another example of the overlap between the first electrode pattern PA and the second electrode pattern PB in the laminate 30A.

[0029] Figure 13 It is used to explain what can be included Figure 1 A diagram of the additional steps in step S2 shown.

[0030] Figure 14 This is a schematic cross-sectional view of a stack 30A with a fixture placed on the upper wafer 10WA.

[0031] Figure 15 This is observed from the normal direction of the principal plane 10a of the upper wafer 10WA. Figure 14 A schematic top view of the stacked body 30A and the fixture shown.

[0032] Figure 16 This is a schematic vertical cross-sectional view used to illustrate the method of deforming the upper wafer 10WA using a jig 50.

[0033] Figure 17 This is a schematic vertical cross-sectional view of the laminate 30A after deformation of the upper wafer 10WA.

[0034] Figure 18 This is a schematic vertical sectional view showing other examples of the shape of a jig with holes.

[0035] Figure 19 This is a schematic vertical sectional view showing yet another example of the shape of a jig with holes.

[0036] Figure 20 This is a schematic vertical cross-sectional view used to illustrate a method of deforming the upper wafer 10WA using a metal film 52 without using a jig 50.

[0037] Figure 21 This is a schematic vertical cross-sectional view used to illustrate a deformation example in which both the upper wafer 10WA and the lower wafer 20WA are deformed.

[0038] Figure 22 This is a schematic vertical cross-sectional view used to illustrate the partial removal of the upper wafer 10WA by laser ablation.

[0039] Figure 23 It shows through Figure 1 A schematic vertical cross-sectional view of an example of a gyroscope obtained by the manufacturing method shown, which serves as a curved surface support structure.

[0040] Figure 24 This is a schematic vertical cross-sectional view used to illustrate the removal of the upper wafer 10WA by etching.

[0041] Figure 25 This is a schematic vertical cross-sectional view used to illustrate the etching process of the upper wafer 10WA and the lower wafer 20WA.

[0042] Figure 26 This is a schematic vertical cross-sectional view used to illustrate an example of pre-forming a protective film 64 on the surface of the upper wafer 10WA and the surface of the lower wafer 20WA.

[0043] Figure 27 Other examples of deforming the upper wafer 10WA using a fixture with holes are shown.

[0044] Figure 28 It is used to explain what can be included Figure 1 A diagram showing the additional steps in the manufacturing method.

[0045] Figure 29 This is a schematic vertical sectional view showing yet another example of the shape of a jig with holes.

[0046] Figure 30 It is used to explain what can be included Figure 1 A diagram of the additional steps in step S1 shown.

[0047] Figure 31 This is a schematic vertical cross-sectional view used to illustrate the formation of a recess 10g on the main surface 10b of a bare wafer 10.

[0048] Figure 32 This is a schematic vertical cross-sectional view showing another example of a first wafer obtained by forming a first electrode pattern PA on a bare wafer 10.

[0049] Figure 33 This is a schematic top view showing another example of a first wafer obtained by forming a first electrode pattern PA on a bare wafer 10.

[0050] Figure 34 This is a schematic vertical cross-sectional view showing a stack 30B consisting of an upper wafer 10WB and a lower wafer 20WA.

[0051] Figure 35 This is a schematic cross-sectional view of a stack 30B with a fixture placed on the upper wafer 10WB.

[0052] Figure 36 This is a schematic vertical cross-sectional view of the laminate 30B after deformation of the upper wafer 10WB.

[0053] Figure 37 This is a schematic vertical cross-sectional view used to illustrate a method of deforming the upper wafer 10WB using a metal film 52 without using a jig 50.

[0054] Figure 38This is a schematic perspective view showing the appearance of an exemplary hemispherical resonant gyroscope.

[0055] Figure 39 It schematically shows a cut near the center. Figure 38 The diagram shows the ZX profile when the gyroscope is in operation.

[0056] Figure 40 This is a schematic perspective view showing other examples of the shape of a harmonic oscillator.

[0057] Figure 41 It schematically shows a cut near the center, such as Figure 40 The diagram shows the ZX profile of the gyroscope.

[0058] (Symbol Explanation)

[0059] 1A: Gyroscope; 10, 20: Bare wafers; 10A: Resonator; 10WA, 10WB: Upper wafers; 10a, 10b: Main surfaces; 10g: Recess; 10h: Island portion; 11A: First electrode; 11c: Driving electrode; 11d: Detecting electrode; 11x: Metal layer; 12: Pillar portion; 12c: Driving electrode; 12d: Detecting electrode; 12x: Metal layer; 14A: Dome, 20A: Support, 20WA: Lower wafer, 20a, 20b: Main face, 20g: Recess, 20h: Island, 22A: Second electrode, 23A: First circuit, 24A: Second circuit, 30A, 30B: Stack, 30ca, 30cb: Cavity, 30t: Cavity, 50, 51, 53, 54, 55, 56: Fixture, 50b, 54b: (Fixture) (The following are the components): Lower surface of the tool; 50h, 53h, 54h, 55h, 56h: Hole; 51h: Bottom hole; 52: Metal film; 53cp, 54cp, 56cp: Protrusion; 54c: Side; 54r, 56r: Opening; 56t: Front end; 62, 64: Protective film; 80A, 80B: Resonator; 81: First electrode; 82: Columnar part; 84A: Dome; 84B: Bowl. Part, 90A, 90B: Support part, 90a: Upper surface, 90b: Lower surface, 90g: Recess, 90t, 90u: Cavity, 92: Second electrode, 140: Edge part, 840: Edge part, 840b: Lower surface, 900A, 900B: Gyroscope, 922: Terminal, PA: Pattern of first electrode, PA1: First layer, PA2: Second layer, PB: Pattern of second electrode Detailed Implementation

[0060] The embodiments of the present invention will be described below. The various features shown in the embodiments described below can be combined with each other. Furthermore, each feature can independently make the invention possible.

[0061] <1. Hemispherical Resonant Gyroscope>

[0062] This application proposes a novel manufacturing method for a curved surface support structure. The following description uses a hemispherical resonant gyroscope as an example of the curved surface support structure. To facilitate understanding of this invention, the basic structure of a hemispherical resonant gyroscope will first be explained.

[0063] Figure 38 The appearance of an exemplary hemispherical resonant gyroscope is shown. Figure 39 The illustration schematically shows a cut near the center. Figure 38 The vertical cross-section of the gyroscope is shown. For ease of explanation, in... Figure 38 and Figure 39 The figure depicts three arrows representing the mutually orthogonal directions of the X, Y, and Z axes. These X, Y, and Z axes do not represent a fixed spatial coordinate system, but rather a relative coordinate system fixed to the gyroscope shown in the figure. Arrows representing these three directions may also be shown in subsequent figures.

[0064] Figure 38 The gyroscope 900A shown includes a resonator 80A and a support portion 90A that supports the resonator 80A. Figure 38 In the illustrated structure, the support 90A is generally plate-shaped, and here, the bottom surface 90b of the support 90A is parallel to the attached... Figure X A rectangle on the Y-plane. The length of one side of a rectangle with a base of 90° is, for example, between 10mm and 20mm.

[0065] The resonator of a hemispherical resonator gyroscope is also called the "shell". Figure 38 and Figure 39 In the example shown, the resonator 80A of the gyroscope 900A has a generally hemispherical bulge on the side opposite to the support portion 90A. However, the center of the outer surface of the resonator 80A is recessed towards the support portion 90A (along the negative Z-axis direction), and a columnar portion 82 extending towards the support portion 90A is formed in the center of the inner side of the resonator 80A. The resonator 80A is connected to and supported by the support portion 90A through this columnar portion 82.

[0066] The harmonic oscillator of a hemispherical resonator gyroscope typically has various shapes, such as bell-shaped, goblet-shaped, or bird bathtub-shaped, which are symmetrical about the central axis. Figure 38 and Figure 39 The shape of the resonator 80A shown is also symmetrical about the aforementioned columnar portion 82 in the XY plane. The resonator 80A includes an upwardly expanding hemispherical dome 84A. Here, a ring-shaped recess 90g is provided on the upper surface 90a of the support portion 90A, and the surface of the recess 90g and the inner surface of the upwardly bulging dome 84A form a ring-shaped cavity 90t inside the gyroscope 900A.

[0067] Figure 40 and Figure 41 Other examples of harmonic oscillator shapes are shown. In these figures, Figure 41 The illustration schematically shows a cut near the center. Figure 40 The vertical cross-section of the gyroscope shown. Figure 40 and Figure 41 The gyroscope 900B shown includes a resonator 80B and a support 90B. The support 90B has a structure substantially the same as the support 90A of the gyroscope 900A described above. On the other hand, the resonator 80B and... Figure 38 and Figure 39 Unlike the resonator 80A shown, it includes a bowl-shaped portion 84B that is recessed in an annular shape towards the support portion 90B with the columnar portion 82 as the center. It is the same as the resonator 80A in that it is connected to and supported by the support portion 90B through the columnar portion 82.

[0068] Thus, the shape of the harmonic oscillator is not limited to an upward bulge. For example... Figure 41 As shown, the gyroscope 900B has a cavity 90u with a smaller volume than the cavity 90t of the gyroscope 900A described above.

[0069] Refer again Figure 38 and Figure 39 The dome 84A has an edge portion 840 arranged in a ring around the columnar portion 82, and is generally axially symmetrical with respect to the columnar portion 82. The lower surface 840b of the edge portion 840 is generally flat, and in this example, the lower surface 840b is generally parallel to the upper surface 90a of the support portion 90A. The edge portion 840 may also be referred to as a "flange".

[0070] The resonator 80A also has one or more first electrodes 81 arranged in a ring on the lower surface 840b of the edge portion 840. On the other hand, the support portion 90A has a plurality of second electrodes 92 arranged on the upper surface 90a opposite to the first electrodes 81 of the resonator 80A. In this example, the second electrodes 92 are arranged in a ring outside the recess 90g.

[0071] The second electrode 92 of the support portion 90A includes both a driving electrode and a detection electrode. The driving electrode applies vibrations of a predetermined frequency to the dome 84A when the gyroscope 900A is operating. On the other hand, the detection electrode detects changes in the electrostatic capacitance between the dome 84A and the support portion 90A. By detecting changes in electrostatic capacitance, the change in angular velocity accompanying the overall rotational motion of the gyroscope 900A can be determined.

[0072] like Figure 38 and Figure 39As shown, terminals 922 for connecting to external circuits can be led out from each of the second electrodes 92 provided on the support portion 90A. These terminals 922, corresponding to the plurality of second electrodes 92, are connected to a drive circuit for applying a predetermined voltage to the drive electrode or a detection circuit for applying a predetermined voltage to the detection electrode when the gyroscope 900A is operating. On the other hand, regarding the resonator 80A, as described above, the operation of the gyroscope 900A requires the application of a predetermined voltage to the plurality of first electrodes 81 on the edge portion 840. If, for example, voltage is to be applied to each of the first electrodes 81 via a wired connection, an electrical connection structure, such as wiring, extending from the first electrodes 81 to the support portion 90A, needs to be formed on the resonator 80A.

[0073] According to the technology described in Patent Document 1, a curved support structure, such as that of a hemispherical resonator gyroscope, is obtained by deforming a wafer whose surface has electrodes formed on it through heating. The advantage of this method is that it eliminates the need to form electrodes on a complex three-dimensional structure, such as the resonator of a hemispherical resonator gyroscope. However, according to the inventors' research, if not only the first electrode 81 but also wiring extending from the first electrode 81 is pre-formed on the wafer, these wirings may break during wafer deformation, thus preventing the attainment of the desired electrical connection.

[0074] In view of the above circumstances, the inventors conducted in-depth research and thus completed the present invention. Embodiments of the present invention provide a method for efficiently forming, for example, a structure that connects the electrodes on the resonator side of a hemispherical resonant gyroscope to an electrode pattern on the support side. According to at least any embodiment of the present invention, the electrodes on the resonator side can be reliably connected to the electrode pattern on the support side.

[0075] <2. Implementation Method of Manufacturing a Hemispherical Resonant Gyroscope>

[0076] Figure 1 An outline of an exemplary manufacturing method for a hemispherical resonant gyroscope according to one embodiment of the present invention is shown. Figure 1 As shown, a method for manufacturing a hemispherical resonator gyroscope includes, for example, a step S1 of preparing a first wafer having a first electrode pattern; a step S2 of obtaining a laminate with an internal cavity by bonding the first wafer with a second wafer having a second electrode pattern; a step S3 of increasing or decreasing the cavity volume by heating the first wafer and / or the second wafer to deform it; and a step S4 of removing a portion of the first wafer to form a resonator whose central portion is supported by the second wafer.

[0077] As will be apparent from the following description, each step of the manufacturing method according to embodiments of the present invention can be implemented using semiconductor manufacturing processes or MEMS manufacturing processes known as those described in Patent Document 1. For reference, the entire disclosure of International Publication No. 2022 / 224704 is incorporated herein by reference.

[0078] (2-1. Step S1 for preparing the first wafer)

[0079] First, a first wafer with a first electrode pattern is prepared. The first wafer can be prepared by purchasing or by forming the first electrode pattern on one main surface of a bare wafer of appropriate shape. As a bare wafer, quartz wafers (fused silica wafers and synthetic quartz wafers), glass wafers (borosilicate glass wafers, low-expansion glass wafers), silicon wafers, etc., can be used.

[0080] Here, after preparing the bare wafer, the first electrode pattern is formed on one side of the main surface of the bare wafer. Figure 2 and Figure 3 An example of a first wafer with a first electrode pattern is shown schematically. Figure 2 The illustration schematically shows a cut near the center. Figure 3 The vertical cross-section shown is for the first wafer.

[0081] exist Figure 2 and Figure 3 In the example shown, a first electrode pattern PA is formed on one main surface 10b of the bare wafer 10. The first electrode pattern PA includes at least one first electrode 11A. By forming the first electrode pattern PA on the bare wafer 10, an upper wafer 10WA, which serves as the first wafer, is obtained from the bare wafer 10. Thus, the step of preparing the first wafer may include the step of forming the first electrode pattern PA on one main surface of the bare wafer.

[0082] In this example, a circular first electrode pattern PA is formed on the main surface 10b of the bare wafer 10. Figure 3 In the illustrated structure, the outer edge of the first electrode pattern PA is approximately the same as the outer diameter of the resonator (which can be described as the outer diameter of the dome). The outer diameter of the gyroscope resonator obtained by the embodiments of the present invention can be, for example, about 10 mm.

[0083] Here, a portion of the first electrode pattern PA is made to function as the first electrode 11A. Figure 3 In the example shown, the annular portion near the outer edge of the first electrode pattern PA ( Figure 3 The portion (schematically indicated by a dark background) functions as a first electrode 11A, which will be placed opposite the second electrode described later.

[0084] In a typical embodiment of the present invention, when forming the first electrode pattern PA, as follows: Figure 2 and Figure 3 As shown, not only is the first electrode pattern PA formed, but a continuous metal layer 11x surrounding the shape of the first electrode pattern PA is also formed on the main surface 10b. As described later, this metal layer 11x can be used as a bonding layer for bonding the upper wafer 10WA to the lower wafer. Figure 3 In the illustrated structure, the metal layer 11x is rectangular, surrounding the first electrode pattern PA. However, this is just one example. As long as it can continuously surround the first electrode pattern PA, the shape of the metal layer 11x can also be circular or other shapes in the top view viewed from the normal direction of the main surface 10b of the bare wafer 10.

[0085] High-melting-point metals such as W, Ta, Nb, V, Ru, Pt, Cr, and Ti can be used as materials for the first electrode pattern PA and the metal layer 11x. The first electrode pattern PA and the metal layer 11x can be obtained by depositing one or more of these materials. The method for forming the first electrode pattern PA and the metal layer 11x is not particularly limited, and methods such as vacuum evaporation, sputtering, ion plating, chemical vapor deposition (CVD), and physical vapor deposition (PVD) can be used. Two or more of these methods can also be combined to form a first electrode pattern PA with a layered structure.

[0086] Figure 4 This is a magnified and schematic diagram showing an example of a cross-section of the first electrode pattern PA. Figure 4 In the illustrated structure, the first electrode pattern PA includes a first layer PA1 and a second layer PA2. The second layer PA2 is a conductive layer located between the first layer PA1 and the main surface 10b of the bare wafer 10.

[0087] The second layer PA2 is formed by sputtering the aforementioned high-melting-point metal onto the main surface 10b of the bare wafer 10. Conversely, the first layer PA1 is formed by vapor deposition of the aforementioned high-melting-point metal onto the second layer PA2. The material used to form the first layer PA1 can be the same as or different from the material used to form the second layer PA2.

[0088] The second layer PA2 functions as the bottom layer of the first layer PA1. By forming the second layer PA2 using sputtering, a denser metal film can be obtained compared to forming the second layer PA2 by vapor deposition. Because the second layer PA2, as the bottom layer, has a denser structure, damage (e.g., cracking) to the first electrode pattern PA in the bare wafer 10 supporting the first electrode 11A can be suppressed in the subsequent step of deforming the bare wafer 10.

[0089] Because the second layer PA2, which forms the bottom layer, has a denser structure, the first electrode pattern PA can adapt to the abrupt shape changes of the bare wafer 10. Since the second layer PA2 adapts to the abrupt shape changes of the bare wafer 10 without breaking, it is possible to prevent more than one conductive layer constituting the first electrode pattern PA from breaking along with the deformation of the bare wafer 10. In other words, it is possible to avoid the loss of electrical connections, for example, between the first electrode 11A and other parts of the first electrode pattern PA, during the deformation of the bare wafer 10.

[0090] Thus, the first electrode pattern PA can have a stacked structure of two or more metal films deposited using different methods. Alternatively, the first electrode pattern PA can also be formed as a single layer on the main surface 10b of the bare wafer 10 by sputtering. By applying sputtering, compared to forming the first electrode pattern PA solely by evaporation, a more reliable curved support structure (e.g., a hemispherical resonator gyroscope) can be advantageously obtained in terms of electrical connection reliability.

[0091] The thickness of the first electrode 11A constituting the first electrode pattern PA is, for example, in the range of 25 nm or more and 500 nm or less. When the first electrode pattern PA has a stacked structure of a first layer PA1 and a second layer PA2, the first layer PA1 has a thickness of, for example, 10 nm or more and 300 nm or less, and the second layer PA2 has a thickness of, for example, 15 nm or more and 200 nm or less.

[0092] (2-2. Step S2 to obtain a laminate with an internal cavity)

[0093] After preparing the upper wafer 10WA, or concurrently with the preparation of the upper wafer 10WA, a lower wafer with a second electrode pattern is prepared. The lower wafer, as the second wafer, is also the same as the upper wafer 10WA and can be prepared either by purchasing it or by forming a second electrode pattern with multiple second electrodes on one main surface of a bare wafer of appropriate shape. Similar to the formation of the upper wafer 10WA, the bare wafer used to form the lower wafer can be a quartz wafer, a glass wafer, a silicon wafer, etc.

[0094] Here, before forming the second electrode pattern, a recess is formed on one side of the main surface of the bare wafer by etching. Figure 5 and Figure 6 An example of a bare wafer after etching is shown schematically. Figure 5 It's equivalent to cutting off near the center. Figure 6 The image shows a vertical cross-sectional view of the wafer. In this example, a ring-shaped recess 20g is formed on one side of the main surface 20a of the bare wafer 20. The size of the recess 20g is sufficient to accommodate the first electrode pattern PA described above and the second electrode pattern described later.

[0095] Here, due to selective etching performed from the main surface 20a side of the bare wafer 20, the result is as follows: Figure 5 and Figure 6 As shown, an island-shaped portion 20h is formed in the annular central portion of the recess 20g, which is not etched and is retained. It should be noted that the same recess can be formed on the bare wafer 10 used to form the upper wafer 10WA, not only on the bare wafer 20, but also on the bare wafer 10, as described later.

[0096] Next, a second electrode pattern is formed on the main surface 20a side of the bare wafer 20. Figure 7 and Figure 8 The bare wafer 20 after the second electrode pattern has been formed is shown schematically. Figure 8 An example of the appearance of a bare wafer 20 with the second electrode pattern as viewed from the normal direction of the main surface 20a is shown. On the other hand, Figure 7 The illustration schematically shows a cut near the center. Figure 8 The vertical cross-section of the wafer shown.

[0097] exist Figure 8 In the example shown, a lower wafer 20WA is obtained from the bare wafer 20 by forming a second electrode pattern PB, including a plurality of second electrodes 22A, each of which is generally arc-shaped, on the main surface 20a side of the bare wafer 20. The material used to form the second electrode pattern PB is the same as the material of the first electrode pattern PA, and one or more materials selected from the group consisting of W, Ta, Nb, V, Ru, Pt, Cr, and Ti can be used. The second electrode pattern PB can be formed using the same film deposition method as the first electrode pattern PA. For example, the second electrode pattern PB can be obtained on the bare wafer 20 by forming a first conductive layer as a sputtering underlayer and a second conductive layer by vapor deposition. The thickness of the second electrode pattern PB is the same as the thickness of the first electrode pattern PA, and can be, for example, in the range of 25 nm or more and 500 nm or less.

[0098] exist Figure 8 In the illustrated structure, the second electrode 22A of the lower wafer 20WA includes multiple groups of driving electrodes 12c and detection electrodes 12d arranged in a ring. As described above, each electrode included in the second electrode 22A is connected to a driving circuit for applying a predetermined voltage to the driving electrode 12c, or a detection circuit for applying a predetermined voltage to the detection electrode 12d when the gyroscope is operating. Figure 8 As shown, in this example, the driving electrodes 12c and the detection electrodes 12d are alternately arranged inside the recess 20g and surround the island portion 20h. From another perspective, the island portion 20h is located at the center D of a virtual circle conceived from the combined driving electrodes 12c and detection electrodes 12d.

[0099] exist Figure 8 In the illustrated structure, the second electrode pattern PB, in addition to having the second electrode 22A (i.e., the driving electrode 12c and the detection electrode 12d), also has a plurality of first circuits 23A extending radially from the aforementioned center D, and a second circuit 24A surrounding the second electrode 22A in a ring shape. Figure 8 As shown, multiple first circuits 23A are respectively connected to the second circuit 24A through the driving electrode 12c and the detection electrode 12d. The second circuit 24A is connected to... Figure 8 The power supply (not shown in the diagram) is grounded here. It should be noted that when the gyroscope is operating, as long as the potential of the first circuit 23A extending from the island portion 20h in the second electrode pattern PB can be fixed to the ground potential, the inclusion of the second circuit 24A in the second electrode pattern PB is not essential in embodiments of the present invention. Here, the second electrode 22A, the first circuit 23A, and the second circuit 24A are all disposed inside the recess 20g.

[0100] Figure 9 Other examples of the PB shape of the second electrode pattern are shown. Figure 9 In the illustrated structure, the second electrode pattern PB and Figure 8 The example shown is the same, including a second electrode 22A, a first circuit 23A, and a second circuit 24A arranged in a ring. Figure 9 In the example shown, terminals 122 are radially extended from each driving electrode 12c and each detection electrode 12d in the second electrode 22A into the second circuit 24A. Since each second electrode 22A has a terminal 122, it facilitates connection to the driving circuit or detection circuit. Each second electrode 22A does not necessarily have a terminal 122. The shape of each second electrode 22A is arbitrary, as long as it can be connected to the driving circuit or detection circuit via wire bonding.

[0101] In addition, Figure 8 and Figure 9 In any of the diagrams, the second electrode pattern PB has a total of 16 second electrodes 22A arranged by bisecting a circle. The number of second electrodes 22A in the second electrode pattern PB is generally a multiple of 4. When the number of second electrodes 22A is, for example, 8, it can be determined whether the detected angular velocity is a false detection caused by manufacturing errors, etc. If the number of second electrodes 22A is further increased to, for example, 16, not only can angular velocity be detected, but the output can also be obtained in the form of angle through integration.

[0102] Here, in parallel with the formation of the second electrode pattern PB, a metal layer 12x, identical in shape to the metal layer 11x in the upper wafer 10WA, is formed on the main surface 20a, continuously surrounding the shape of the second electrode pattern PB. The metal layer 12x is spatially separated from the second electrode 22A of the second electrode pattern PB and has no electrical connection with the second electrode pattern PB.

[0103] After obtaining the upper wafer 10WA and the lower wafer 20WA, they are stacked and bonded together to form a laminate with an internal cavity. Figure 10 A schematic diagram shows a vertical cross-section of the laminate 30A obtained by bonding the upper wafer 10WA and the lower wafer 20WA.

[0104] from Figure 10 It can be seen that, firstly, with the first electrode 11A of the upper wafer 10WA (here, the first electrode 11A is part of the circular plate-shaped first electrode pattern PA) aligned with the second electrode 22A of the lower wafer 20WA, the upper wafer 10WA and the lower wafer 20WA are stacked together. At this time, the first electrode 11A and the second electrode 22A are opposite each other with a gap of size determined by the depth of the recess 20g.

[0105] When the upper wafer 10WA is stacked on the lower wafer 20WA, the circular center C of the first electrode pattern PA on the upper wafer 10WA side (refer to) Figure 3 ), roughly aligned with the center D of the aforementioned virtual circle on the 20WA side of the lower wafer within the XY plane of the figure (refer to Figure 8 The alignment of the upper wafer 10WA and the lower wafer 20WA can be performed using a suitable alignment device such as a double-sided mask aligner, and the bonding of the upper wafer 10WA and the lower wafer 20WA can be performed with the alignment accuracy of the alignment device. For example, by using a double-sided mask aligner, the magnitude of the alignment error between the first electrode 11A and the second electrode 22A can be controlled within the error range of semiconductor manufacturing processes (e.g., less than 5 μm).

[0106] Figure 11 and Figure 12 This diagram illustrates the extraction of the first electrode pattern PA and the second electrode pattern PB from the laminate 30A. The first electrode 11A and the second electrode 22A in the laminate 30A are spaced apart and opposite to each other. Figure 11 and Figure 12 In the diagram, shading is used to indicate the portion of the first electrode pattern PA that overlaps with the second electrode 22A of the second electrode pattern PB. In these examples, the first electrode 11A is the portion of the first electrode pattern PA that overlaps with the second electrode 22A of the second electrode pattern PB in the top view. Figure 12In the example shown, the first electrode 11A of the first electrode pattern PA covers the entirety of the second electrode 22A of the second electrode pattern PB, but is not limited to this, such as... Figure 11 As shown, it is sufficient that the first electrode 11A covers a portion of the second electrode 22A.

[0107] The bonding of the upper wafer 10WA and the lower wafer 20WA can be achieved using conventional bonding equipment and substrate bonding techniques such as diffusion bonding and anodic bonding. The bonding method for the upper wafer 10WA and the lower wafer 20WA is not limited to a specific method; it can be appropriately selected based on the materials of the bare wafers 10 and 20.

[0108] Not limited to direct bonding between wafers, bonding mediated by materials other than the wafer constituent materials (such as metal layers) can also be applied. Here, as... Figure 10 As shown, when the upper wafer 10WA is stacked on the lower wafer 20WA, the metal layer 11x of the upper wafer 10WA and the metal layer 12x of the lower wafer 20WA are in contact with each other. In this state, by applying heat and pressure, the metal layers 11x and 12x can function as bonding layers, and the bonding between the upper wafer 10WA and the lower wafer 20WA is achieved through diffusion bonding.

[0109] Here, as referenced Figure 3 and Figure 8 As described, metal layer 11x has a shape that continuously surrounds the first electrode pattern PA, and similarly, metal layer 12x has a shape that continuously surrounds the second electrode pattern PB. Furthermore, from... Figure 3 and Figure 8 As can be seen, when the upper wafer 10WA and the lower wafer 20WA are stacked with the first electrode 11A aligned with the second electrode 22A of the lower wafer 20WA, in this example, the continuously formed metal layer 11x is opposite to the continuously formed metal layer 12x. Therefore, by bonding the upper wafer 10WA and the lower wafer 20WA, a ring-shaped recess 20g is formed on the main surface 20a side of the lower wafer 20WA, and a ring-shaped hermetically sealed cavity 30ca is formed inside the laminate 30A. Furthermore, as described later, the bonding of the upper wafer 10WA and the lower wafer 20WA can also be performed under reduced pressure.

[0110] like Figure 10As shown, in the second electrode pattern PB of the lower wafer 20WA, the portion located on the top surface of the island portion 20h contacts the first electrode pattern PA of the upper wafer 10WA when the upper wafer 10WA is stacked on the lower wafer 20WA. Therefore, by applying, for example, heat and pressure to the interface of these electrode patterns, in the bonding step between the upper wafer 10WA and the lower wafer 20WA, the first circuit 23A of the first electrode pattern PA and the second electrode pattern PB is electrically connected at the position of the island portion 20h. Thus, the step of bonding the upper wafer 10WA and the lower wafer 20WA includes the step of electrically connecting the first electrode 11A to the first circuit 23A of the second electrode pattern PB.

[0111] For reference Figures 5-12 The steps described above for forming a laminate by bonding the upper wafer 10WA and the lower wafer 20WA are as follows (see reference). Figure 1 Step S2 may include additional steps related to the formation of the next wafer 20WA as the second wafer. Figure 13 It shows that it can be included Figure 1 Example of additional steps in step S2 shown. Figure 13 Example, Figure 1 The step S2 shown may include: step S21 of preparing a bare wafer 20 for forming the lower wafer 20WA; step S22 of forming a recess 20g on one side main surface 20a of the bare wafer 20 by etching; step S23 of forming a second electrode pattern PB containing a plurality of second electrodes 22A in the recess 20g; and step S24 of stacking and bonding the upper wafer 10WA and the lower wafer 20WA by aligning the first electrode pattern PA with the second electrode pattern PB.

[0112] Depend on Figure 10 As can be seen, after the bonding between the upper wafer 10WA and the lower wafer 20WA is completed, the first electrode pattern PA and the second electrode pattern PB are located inside the cavity 30ca of the laminate 30A. From the viewpoint of accommodating the first electrode pattern PA and the second electrode pattern PB inside the cavity 30ca, for example, the depth of the recess 20g formed on the bare wafer 20 should be greater than the total thickness when the first electrode 11A and the second electrode 22A are stacked. In this example, the depth of the recess 20g determines the size of the gap between the first electrode 11A on the resonator side and the second electrode 22A on the support side. The depth of the recess 20g only needs to be sufficient to accommodate at least the size of the first electrode pattern PA and the second electrode pattern PB. If the depth of the recess 20g is less than 5 μm, the voltage applied to the drive electrode 12c can be reduced to less than a few volts (e.g., less than 10 volts), which is therefore advantageous.

[0113] (2-3. Step S3: deforming the first wafer and / or the second wafer)

[0114] Next, by heating the laminate 30A, one or both of the upper wafer 10WA and the lower wafer 20WA are deformed, thereby increasing or decreasing the volume of the cavity 30ca. Before heating the laminate 30A, a jig of a predetermined shape is first placed on the other main surface 10a of the upper wafer 10WA, in other words, on the main surface 10a of the upper wafer 10WA on the side where the first electrode pattern PA is not provided.

[0115] Figure 14 The diagram schematically illustrates a stack 30A with a fixture placed on the upper wafer 10WA. Figure 15 This schematically illustrates the view from the normal direction of the main face 10a of the upper wafer 10WA (here, when looking in the negative Z-axis direction). Figure 14 An example of the appearance of the laminate 30A and the fixture shown. Figure 14 and Figure 15 As shown, this illustrates an example of applying a fixture 50 with a hole 50h. In Figure 14 and Figure 15 In the illustrated structure, hole 50h is a cylindrical through hole extending vertically to the lower surface 50b of fixture 50. However, it is not limited to this example; hole 50h can also be a bottomed hole.

[0116] The center of hole 50h in fixture 50 is aligned with the center C of the circular plate of the first electrode pattern PA (see reference). Figure 3 ) and the center D of the aforementioned virtual circle (refer to Figure 8 Consistent with. For example... Figure 15 As shown, a portion of the main surface 10a of the upper wafer 10WA is exposed inside the hole 50h of the fixture 50, while the other areas of the main surface 10a are covered by the fixture 50. Figure 15 As suitably shown, the first electrode 11A of the first electrode pattern PA is located outside the opening of the hole 50h in the fixture 50. As will become clear in the following description, the circular diameter of the hole 50h determines the approximate inner diameter of the dome edge.

[0117] After placing the fixture 50 on the upper wafer 10WA, the laminate 30A with the fixture 50 placed on it is placed in a heating furnace, and the laminate 30A is heated to the temperature at which the materials of the upper wafer 10WA and the lower wafer 20WA soften. If, for example, quartz is chosen as the material for the bare wafers 10 and 20, the temperature in the heating furnace is raised to 1200°C to 1600°C; if borosilicate glass is chosen, the temperature in the heating furnace is raised to 500°C to 900°C.

[0118] In a typical embodiment of the invention, heating of the laminate 30A is performed at different ambient pressures than when it is joined with the upper wafer 10WA and the lower wafer 20WA. For example, by evacuating the furnace to reduce the internal atmospheric pressure to below atmospheric pressure (standard atmospheric pressure 101,325 Pa in this specification), the pressure difference between the upper wafer 10WA and the cavity 30ca of the laminate 30A can be used to deform the upper wafer 10WA. When the atmospheric pressure inside the furnace decreases below the pressure inside the cavity 30ca, the base material (e.g., quartz) of the upper wafer 10WA softens with heating, and the expansion of the gas inside the cavity 30ca causes the portion of the upper wafer 10WA located inside the fixture 50 hole 50h to expand outwards from the laminate 30A (see reference). Figure 16 In other words, the volume of cavity 30ca increases, forming a larger cavity 30t inside the laminate 30A.

[0119] Due to the deformation of the upper wafer 10WA, the portion of the main surface 10a of the upper wafer 10WA located inside the hole 50h of the fixture 50 is deformed into a curved shape. Thus, by heating the laminate 30A and utilizing the pressure difference between the inside of the cavity 30ca and the outside of the laminate 30A, a result can be obtained as follows: Figure 38 The hemispherical structure shown is similar to the domed 84A. Figure 16 In the example shown, as the volume of cavity 30ca increases, the main surface 10a rises in a ring-like shape, forming a surface with a shape like a ring-shaped convex surface when a toroidal body is cut in half.

[0120] On the other hand, the shape of the portion of the lower surface 50b of the contact fixture 50 in the upper wafer 10WA remains unchanged as a plate. Here, as... Figure 15 As shown, the opening of the hole 50h in the fixture 50 almost coincides with the inner edge of the first electrode 11A of the first electrode pattern PA. Therefore, the portion of the main surface 10b of the upper wafer 10WA (also referred to as the lower surface of the upper wafer 10WA) where the first electrode 11A is formed remains almost flat. That is, the size of the gap formed between the first electrode 11A on the upper wafer 10WA side and the second electrode 22A on the lower wafer 20WA side is approximately the same before and after the laminate 30A is heated.

[0121] In this way, by partially pressing the surface of the upper wafer 10WA with the jig 50, a portion of the upper wafer 10WA can be selectively deformed. As will be explained later, the edge of the rounded top can be formed from the portion of the upper wafer 10WA where the deformation is suppressed by the jig 50.

[0122] As described above, the portion of the first electrode pattern PA that overlaps with the island portion 20h of the lower wafer 20WA is bonded to the second electrode pattern PB of the lower wafer 20WA. Therefore, in the portion of the upper wafer 10WA located inside the hole 50h of the fixture 50, the portion near the center C of the first electrode pattern PA does not rise upwards, but remains near the island portion 20h. As a result, as schematically shown... Figure 16 As shown, a columnar portion 12 of a resonator is formed from a portion of the upper wafer 10WA.

[0123] Thus, the fixture 50 functions to suppress partial deformation of the upper wafer 10WA. After deforming the portion of the upper wafer 10WA located inside the hole 50h in the fixture 50, the shape of the main surface 10a of the upper wafer 10WA (here, a toroidal shape) is fixed by slow cooling. After obtaining the toroidal shape of the upper wafer 10WA, the fixture 50 can be removed from the laminate 30A to obtain the following... Figure 17 The structure is shown. It should be noted that the material of jig 50 can be appropriately selected from the viewpoint of avoiding jig 50 becoming fixed to the upper wafer 10WA. A typical material for jig 50 is glassy carbon.

[0124] Figure 18 Other examples of fixture shapes with holes are shown. Figure 18 The jig 53 shown has a protrusion 53cp at the center of the hole 53h. In this example, the protrusion 53cp has a rod-like shape extending toward the opening of the hole 53h, and the top surface (e.g., a plane) of the rod-like shape contacts the main surface 10a of the upper wafer 10WA. Thus, by using the jig 53 with the protrusion 53cp provided inside the hole 53h, the center of the upper wafer 10WA can be pressed down from above by the protrusion 53cp. As a result, during the heating step, deformation of the portion of the upper wafer 10WA that overlaps with the island portion 20h of the lower wafer 20WA can be suppressed, thereby more reliably ensuring the electrical connection between the first electrode pattern PA and the second electrode pattern PB.

[0125] Figure 19 Another example of a fixture shape with holes is shown. Figure 19 The jig 51 shown has a bottomed hole 51h in the shape of a ring. In this example, the main surface 10a of the upper wafer 10WA is deformed to conform to the shape of the inner surface of the bottomed hole 51h. In this way, the jig can also function as a mold that determines the shape of the dome of the resonator. During the heating step, by utilizing the shape of the hole in the jig to limit the deformation of the wafer, unnecessary deformation (e.g., unnecessary expansion) of the wafer surface can be avoided, thereby achieving the desired resonator shape.

[0126] On the main surface 10a of the upper wafer 10WA, fixtures 50, 51, or 53 may not be configured; instead, it may be arranged as follows: Figure 20 As shown, a metal film 52 is formed on a portion of the main surface 10a of the upper wafer 10WA. In this case, the metal film 52 suppresses the elongation of the upper wafer 10WA caused by heating, thereby allowing deformation of the portion not covered by the metal film 52 while suppressing deformation of the portion covered by the metal film 52. The material of the metal film 52 is the same as that used to form the first electrode pattern PA or the second electrode pattern PB; high-melting-point metals such as W, Ta, Nb, V, Ru, Pt, Cr, and Ti can be used. The metal film 52 can be formed by vacuum evaporation, sputtering, ion plating, CVD, and PVD, as well as by electroless plating and electroplating. The typical thickness of the metal film 52 is on the order of several μm.

[0127] After obtaining the annular shape of the upper wafer 10WA, the metal film 52 is removed by etching to obtain a shape similar to... Figure 17 The same shape as the upper wafer 10WA is shown. In this way, by using the metal film 52 as a fixture, local deformation of the upper wafer 10WA caused by heating can also be achieved.

[0128] In this example, utilizing the pressure difference between the cavity 30ca and the outside of the laminate 30A, the upper wafer 10WA, constituting the laminate 30A, is selected for local deformation. However, this is not a limitation; the upper wafer 10WA and the lower wafer 20WA can also be locally deformed separately. For example, as... Figure 21 As shown, the laminate 30A is positioned on a fixture 55 having the same holes 55h as the jig 50. The fixture 50 is positioned on the laminate 30A. By heating the laminate 30A, not only can the upper wafer 10WA be locally deformed, but the lower wafer 20WA can also be locally deformed. In this case, as... Figure 21 As illustrated in the diagram, the cavity 30ca can expand approximately symmetrically relative to the horizontal plane.

[0129] Thus, between step S2 of forming the laminate and step S3 of deforming the first wafer and / or the second wafer, a step of configuring a fixture on one side of the wafer's main surface can also be performed. Using a fixture with holes, the portion of one or both of the upper wafer 10WA and the lower wafer 20WA located inside the fixture holes can be selectively deformed.

[0130] Reference Figures 14-21In the illustrated example, by performing the heating step of the laminate 30A under reduced pressure, the volume of the internal cavity 30ca of the laminate 30A is increased. Conversely, the volume of the cavity 30ca can also be reduced during the heating step of the laminate 30A. For example, the bonding of the upper wafer 10WA and the lower wafer 20WA can be performed under reduced pressure.

[0131] By performing the bonding of the upper wafer 10WA and the lower wafer 20WA under reduced pressure, the pressure in the cavity 30ca inside the laminate 30A can be lower than atmospheric pressure. If the laminate 30A thus obtained is heated at, for example, atmospheric pressure, as the base materials of the upper wafer 10WA and the lower wafer 20WA soften, the upper wafer 10WA and the lower wafer 20WA will deform by bringing their lower surfaces closer together. For example, the outer surface of the upper wafer 10WA will form a ring-shaped indentation towards the lower wafer 20WA. Therefore, due to the deformation of the upper wafer 10WA, a structure with a shape resembling that of the lower wafer 20WA can be obtained from the upper wafer 10WA. Figure 40 and Figure 41 The resonator shown is a resonator with a ring-shaped concave curved surface, similar to the resonator 80B shown.

[0132] To prevent the upper wafer 10WA from warping due to heat from the laminate 30A, the aforementioned fixture 50 can be fixed to the main surface 10a (which may be referred to as the upper surface of the upper wafer 10WA), selectively deforming only the portion of the upper wafer 10WA located inside the hole 50h of the fixture 50. Alternatively, the entire main surface of one of the upper wafer 10WA and the lower wafer 20WA can be fixed to a rigid, heat-resistant plate (such as a metal plate), selectively deforming only the other of the upper wafer 10WA and the lower wafer 20WA.

[0133] (2-4. Step S4 in forming the harmonic oscillator)

[0134] Next, a resonator is formed from the upper wafer 10WA. In this embodiment, the shape of the resonator is obtained from the upper wafer 10WA by removing a portion of the upper wafer 10WA from the structure after slow cooling.

[0135] Localized removal of material on a 10WA wafer can be achieved using physical processes such as machining (e.g., ultrasonic machining) and chemical processes such as etching. For example, as in... Figure 22As schematically illustrated, a portion of the upper wafer 10WA can be removed in a ring-like pattern centered on the columnar portion 12 by laser ablation irradiated by a laser beam LB. In other words, the upper wafer 10WA is cut along the circumference centered on the island portion 20h of the lower wafer 20WA, for example, along the outer edge of the first electrode pattern PA, by irradiating a laser beam. This delineates the outer edge of the resonator's edge portion. For example, a carbon dioxide (CO2) laser can be used for laser ablation.

[0136] Thus, by removing a portion of the upper wafer 10WA around the center of the annular cavity 30t, the cavity 30t is connected to the outside of the stack 30A, and the portion of the upper wafer 10WA corresponding to the top of the resonator is separated from the rest of the upper wafer 10WA. As a result, as... Figure 22 As shown, a resonator 10A with a dome 14A can be obtained from the upper wafer 10WA.

[0137] like Figure 22 As shown, the resonator 10A has a columnar portion 12 extending upward from the lower wafer 20WA, and a dome 14A including a ring-shaped expanded portion. The dome 14A and... Figure 38 and Figure 39 Like the dome 84A shown, it is symmetrical about the columnar portion 12 and includes an edge portion 140 arranged in a ring around the columnar portion 12.

[0138] The lower wafer 20WA can be cut into a predetermined shape as needed. By removing unnecessary portions to form the support portion 20A from the lower wafer 20WA, the following can be obtained: Figure 23 The gyroscope 1A shown has a support portion 20A with a second electrode pattern PB and a resonator 10A supported by the support portion 20A at its center.

[0139] By applying laser processing to partially remove the upper wafer 10WA, the shape of the dome 14A can be obtained with the mechanical precision of the laser processing apparatus. When determining the laser irradiation position, for example, the shape of the second electrode 22A can be used as an alignment mark. Alternatively, dummy electrodes or wiring can be formed on the upper wafer 10WA or the lower wafer 20WA as fiducial marks.

[0140] In laser ablation, by appropriately adjusting parameters such as laser wavelength, focal length, irradiation power density, pulse width, and repetition frequency, the upper wafer 10WA of the laminate 30A can be selectively processed while avoiding damage to the lower wafer 20WA. Alternatively, the upper wafer 10WA and the lower wafer 20WA can be cut in one operation by adjusting these parameters.

[0141] Alternatively, laser ablation can be used to form the resonator 10A from the upper wafer 10WA by etching. When forming the resonator 10A by etching, for example, by using a reference... Figures 1 to 21 The process described is the same as the one described above, preparing to form a stacked body 30A with an internal annular cavity 30t. Next, as... Figure 24 As schematically shown, a protective film 62 is formed on the entire upper surface of the upper wafer 10WA, i.e., the main surface 10a, and a portion of the main surface 20b of the lower wafer 20WA. The main surface 20b of the lower wafer 20WA is the opposite side of the main surface 20a, corresponding to the lower surface of the lower wafer 20WA.

[0142] The protective film 62 functions as an etch resist in the subsequent formation of the resonator. As an etchant for the upper wafer 10WA, if hydrofluoric acid (HF) or buffered hydrofluoric acid (BHF) is to be used, an Au film or a Cr film can be used as the protective film 62.

[0143] Next, a portion of the upper wafer 10WA is removed by wet etching of the laminate 30A, leaving the portion of the upper wafer 10WA that should become the resonator 10A. The etchant can be appropriately selected based on the material of the protective film 62. If the laminate 30A is immersed in the aforementioned etchant (e.g., hydrofluoric acid), the portion of the lower wafer 20WA not covered by the protective film 62 will be removed, such as... Figure 25 As schematically shown by the thick dashed arrow Et, the etchant enters the cavity 30t of the stack 30A. As the etchant enters the cavity 30t, the area exposed from the first electrode pattern PA on the main surface 10b of the upper wafer 10WA comes into contact with the etchant. As a result, the portion of the upper wafer 10WA that should become the resonator 10A can be retained, while other portions of the upper wafer 10WA can be selectively removed.

[0144] After forming the resonator 10A from the upper wafer 10WA, the protective film 62 on the laminate 30A is removed. If, for example, a Cr film is applied to the protective film 62, the Cr film can be removed, for example, using a cerium ammonium nitrate solution. By removing the protective film 62, a resonator 10A can be obtained. Figure 23 The gyroscope 1A shown has the same three-dimensional structure. Using etching, the shape of the resonator 10A can be achieved with precision equivalent to that of lithography.

[0145] By using a material resistant to the etchant used to etch bare wafers 10 and 20 to form the protective film 62, etching damage during the formation of the resonator 10A due to partial removal of the upper wafer 10WA can be reduced. The material of the protective film 62 can be a high-melting-point metal resistant to the etchant used for wafer etching. Advantageously, a metal that can be selectively removed after the formation of the resonator 10A (e.g., W or Cr) is used as the material of the protective film 62.

[0146] It should be noted that, in Figure 25 In the method shown for separating the resonator 10A from the wafer, the etchant contacts the first electrode pattern PA and the second electrode pattern PB, as well as the area exposed from these electrode patterns on the inner surface of the cavity 30t, potentially causing etching damage to the wafer material and the electrode patterns. Therefore, after obtaining the upper wafer 10WA and the lower wafer 20WA, but before obtaining the laminate 30A through them, as... Figure 26 As shown, a protective film 64 can be formed in advance on the surface of the upper wafer 10WA and the surface of the lower wafer 20WA.

[0147] <3. Electrical connection between resonator 10A and support 20A>

[0148] For reference Figure 10 As explained, in this embodiment, during the step of bonding the upper wafer 10WA and the lower wafer 20WA, an electrical connection is formed between the first electrode pattern PA of the upper wafer 10WA and the second electrode pattern PB of the lower wafer 20WA. More specifically, other portions of the first electrode pattern PA that are continuous from the first electrode 11A (the portion of the first electrode pattern PA located near the circular plate-shaped center C of the first electrode pattern PA) contact the portion of the second electrode pattern PB located on the top surface of the island-shaped portion 20h, thereby forming a mechanical and electrical connection between the first electrode 11A in the first electrode pattern PA and the second electrode pattern PB, especially with the first circuit 23A (see reference). Figure 8 Electrical connection between ).

[0149] Here, comparison Figure 14 and Figure 16 It is known that the shape of the upper wafer 10WA may change significantly with the change in the volume of the cavity 30ca. In particular, the portion of the upper wafer 10WA covered by the fixture 50, and the boundary and vicinity of the portion located inside the hole 50h of the fixture 50 (in... Figure 16 (Represented by the dashed circle Sb1 in the middle), the shape of the main face 10b of the upper wafer 10WA may undergo drastic changes. Figure 16 In the example shown, the upper wafer 10WA bends upward at the opening of the hole 50h in the fixture 50, and the main surface 10b supporting the first electrode pattern PA forms an angular shape at the inner edge of the edge 140 corresponding to the dome 14A. Therefore, during the deformation of the upper wafer 10WA, the first electrode pattern PA on the main surface 10b is also greatly stretched at this angular position, which may cause, for example, cracks or breaks in the first electrode pattern PA. If such a failure occurs in the first electrode pattern PA, it may lead to the loss of electrical connection between the first electrode 11A and the second electrode pattern PB.

[0150] However, in the above example, the first electrode pattern PA includes a substrate formed by sputtering, or the first electrode pattern PA itself is formed by sputtering. By applying sputtering, a denser conductive layer can be obtained; therefore, even if the main surface 10b supporting the first electrode pattern PA undergoes a drastic change in shape, a break in the wire at that location can be avoided. In other words, according to this embodiment, the first electrode 11A on the resonator 10A side can be more reliably connected to the second electrode pattern PB on the support 20A side, thereby achieving a highly reliable electrical connection between the resonator 10A and the support 20A.

[0151] The inventor, according to Figure 1 The steps shown are used to create a product similar to... Figure 23 Using the same curved support structure as the gyroscope 1A shown as a sample, the influence of the first electrode pattern PA deposition method on the quality of the first electrode pattern PA was evaluated. Sample 1, with a monolayer first electrode pattern PA formed by sputtering, was fabricated. The conductivity between the first electrode 11A on the edge and the portion of the first electrode pattern PA on the inner surface of the dome was investigated by contacting the probe of the testing instrument, yielding a resistance value of 100–120 Ω. Similarly, the conductivity between two points symmetrical with respect to the columnar portion on the inner surface of the dome of the first electrode pattern PA was investigated using the same method, also yielding a resistance value of 100–120 Ω. In contrast, in sample 2, with a monolayer first electrode pattern PA formed by vapor deposition, conductivity could not be confirmed. Thus, applying the sputtering method to the formation of the first electrode pattern PA is highly effective for forming a structure on the resonator that connects the resonator-side electrode to the support-side electrode pattern.

[0152] It should be explained that, for example Figure 21 In the example shown, when both the upper wafer 10WA and the lower wafer 20WA are partially deformed, it is advantageous if the second electrode pattern PB includes an underlayer formed by sputtering, or if the entire second electrode pattern PB is formed by sputtering. This is because, similar to the first electrode pattern PA on the upper wafer 10WA, it can reduce the probability of faults such as open circuits within the second electrode pattern PB caused by deformation of the lower wafer 20WA.

[0153] <4. Other examples of implementing electrical connection structures>

[0154] As described above, in step S3, which deforms the first wafer and / or the second wafer by heating, by relatively reducing the external pressure of the laminate 30A, the pressure difference between the inside of the cavity 30ca and the outside of the laminate 30A can be used to deform, for example, the upper wafer 10WA. At this time, if the pressure inside the cavity 30ca is lower than, for example, atmospheric pressure, the tensile stress caused by the pressure difference can be mitigated, thereby suppressing abrupt changes in the shape of the main surface 10b of the upper wafer 10WA during deformation. In other words, damage to the conductive layer constituting the first electrode pattern PA caused by deformation due to tensile stress can be reduced. Therefore, reducing the pressure inside the cavity 30ca can suppress abrupt changes in the shape of the main surface 10b of the upper wafer 10WA, thereby helping to suppress faults such as wire breaks.

[0155] From the perspective of preventing line breaks in the first electrode pattern PA, in step S3 above, for example, if the upper wafer 10WA is deformed under atmospheric pressure, it is beneficial if the pressure inside the cavity 30ca is in the range of 0.1 to 0.5 standard atmospheres, and even more beneficial if it is in the range of 0.1 to 0.3 standard atmospheres. Furthermore, if the pressure difference between the cavity 30ca and the outside of the laminate 30A is too small, the desired dome shape may not be formed due to insufficient deformation. However, by appropriately adjusting other parameters such as the temperature during heating of the laminate 30A and the material selection of the bare wafers 10 and 20, the desired shape (e.g., hemispherical surface and annular convex surface) can be achieved while avoiding line breaks.

[0156] In addition to the selection of the film formation method of the first electrode pattern PA and the reduction of the internal pressure of the cavity 30ca, for example, the shape of the fixture used to deform the upper wafer 10WA (and / or the lower wafer 20WA) can also suppress the occurrence of wire breaks in the first electrode pattern PA. Figure 27 Other examples of wafer deformation using a fixture with holes are shown. (See reference) Figure 16 Compared to the examples given, Figure 27 In the example shown, instead of jig 50, jig 54 with holes 54h is disposed on the main surface 10a, which is the upper surface of the laminate 30A, thereby performing the deformation step of the upper wafer 10WA. The jig 54 and... Figure 18 Like the jig 53 shown, it has a protrusion 54cp located in the center of the hole 54h.

[0157] like Figure 27 As shown, the fixture 54 has a lower surface 54b opposite to the upper surface of the laminate 30A, and a side surface 54c with a pre-defined hole 54h. Figure 27 As shown, in this example, the lower surface 54b of the fixture 54 is smoothly and continuously connected to the side surface 54c of the hole 54h. That is, in Figure 27 In the illustrated structure, with Figure 18 Unlike the hole 53h shown, the opening 54r on the lower surface 54b side of hole 54h has a rounded corner shape.

[0158] As described above, as the laminate 30A is heated, the bare wafer 10, which serves as the substrate for the upper wafer 10WA, gradually softens. The portion of the upper wafer 10WA located inside the hole 54h in the fixture 54 is lifted upwards due to the pressure difference between the cavity 30ca and the outside of the laminate 30A. At this time, because the hole 54h has an opening 54r at its opening position, it deforms into a shape (here, a smooth curved surface) that mimics the shape of the opening 54r in the fixture 54, as part of the main surface 10a on the upper surface of the upper wafer 10WA. Thus, in Figure 27 In the example shown, the portion of the main surface 10b located below the opening 54r of the fixture 54 on the opposite side of the main surface 10a ( Figure 27 The part represented by the dashed circle Sb1 is curved.

[0159] By using a fixture with holes including rounded openings, angular shapes can be avoided on the main surface 10b supporting the first electrode pattern PA. Therefore, sharp bending of the wafer 10WA at, for example, the inner edge of the dome 14A edge 140 can be prevented, thus avoiding excessive stretching of the first electrode pattern PA. In other words, problems such as broken lines in the first electrode pattern PA caused by deformation of the upper wafer 10WA are suppressed, thereby enabling the formation of more reliable wiring on the resonator 10A.

[0160] Thus, the manufacturing method of curved surface support structures, such as Figure 28 For example, between step S2 of obtaining the laminate and step S3 of deforming the wafer constituting the laminate, a step S25 may be included, in which a fixture having a hole with rounded corner openings is disposed on the laminate. By using the fixture, in step S3 of deforming the wafer constituting the laminate, a portion of one side of the main surface of the wafer constituting the laminate can be deformed into a shape that conforms to the shape of the fixture opening.

[0161] exist Figure 27 In the illustrated structure, jig 54 and Figure 18 Similar to the fixture 53 shown, it has a protrusion 54cp located in the center of the hole 54h. Because the fixture 54 has the protrusion 54cp, the expansion of the central part of the upper wafer 10WA can be pressed by the protrusion 54cp, so that the first electrode pattern PA can be more reliably connected to the second electrode pattern PB.

[0162] Furthermore, in this example, such as Figure 27 As shown under magnification, the front end of protrusion 54cp has a rounded shape (e.g., hemispherical). (As seen from...) Figure 27 and Figure 16 It can be seen that the angular shape on the surface supporting the first electrode pattern PA may appear not only in the portion corresponding to the inner edge of the edge 140, but also near the columnar portion 12. Figure 16 and Figure 27 (The portion shown by the dashed circle Sb2). (As shown in the example). Figure 27 As shown in the fixture 54, the front end of the protrusion 54cp has a rounded shape, and the portion of the main surface 10b of the upper wafer 10WA that bends near the columnar portion 12 can also be made into a curved surface that mimics the shape of the front end of the protrusion 54cp. In other words, it is possible to avoid the formation of an angular shape in the portion of the main surface 10b near the columnar portion 12, thereby suppressing the occurrence of wire breaks and the like in the first electrode pattern PA near the columnar portion 12.

[0163] Furthermore, the hole 54h of the fixture 54 is not limited to having a bottom hole; it can be any structure capable of holding the protrusion 54cp in a predetermined position. For example, the protrusion 54cp can be supported at the center of the hole 54h by multiple beams extending radially from the center of the hole 54h toward the side 54c.

[0164] Figure 29 Another example of a fixture shape with holes is shown. Figure 29 The hole 56h of the fixture 56 shown is the same as the reference hole 56h. Figure 19 The example illustrated is a toroidal shape with a bottom hole, and similar to... Figure 27 The hole 54h shown also has a rounded opening 56r. Furthermore, in this example, a protrusion 56cp with a curved front end 56t is formed in the center of the hole 56h. As in this example, the shape of the fixture hole can be used to control the shape of the resonant ring of the resonator while avoiding angular shapes on the main surface of the supporting electrode pattern (here, the main surface 10b).

[0165] <5. Other embodiments of the manufacturing method>

[0166] In the examples described above, electrode patterns are formed on a three-dimensional structure by deforming the wafer after forming the electrode pattern on the flat wafer. However, the present invention is not limited to this. As will be explained below, electrode patterns can also be formed on a surface-processed wafer before performing the heat deformation step.

[0167] (5-1. Step S1 for preparing the first wafer)

[0168] Figure 30 An example of an additional step that can be included in step S1 of preparing the first wafer is shown. For example... Figure 30For example, step S1 of preparing the first wafer may include: step S11 of forming a ring-shaped recess on the bare wafer; and step S12 of forming a conductive layer as a bottom layer or as a first electrode pattern by sputtering.

[0169] Here, as Figure 31 As shown, a recess 10g is first formed on one main surface 10b of the bare wafer 10. As described later, by pre-setting the recess 10g on the bare wafer 10, selective deformation of the pre-thinned portion of the wafer occurs during the wafer deformation step by heating. Compared to deforming a flat wafer, this avoids abrupt deformation of the wafer surface. Due to the reduction in wafer deformation, the stress applied to the electrode pattern on the wafer by wafer deformation is reduced, mitigating damage to the conductive layer constituting the electrode pattern.

[0170] From the top view viewed perpendicular to the main surface 10b, the shape of the recess 10g is similar to... Figure 6 The recess 20g of the bare wafer 20 shown is also ring-shaped. In this example, an island-shaped portion 10h surrounded by the recess 10g is formed on the bare wafer 10. The diameter of the island-shaped portion 10h, which is also the inner diameter of the recess 10g, can be approximately the same as that of the island-shaped portion 20h on the bare wafer 20. However, the outer diameter of the recess 10g, which corresponds to the inner diameter of the edge of the resonant ring, is smaller than the outer diameter of the recess 20g formed on the bare wafer 20.

[0171] Next, as in reference Figures 2-4 As in the illustrated example, a first electrode pattern PA is formed on the main surface 10b of the bare wafer 10. The first electrode pattern PA may also have a stacked structure of two or more layers, including a second layer PA2 formed by sputtering and a first layer PA1 on the second layer PA2.

[0172] Figure 32 and Figure 33 Other examples of a first wafer obtained by forming a first electrode pattern PA on a bare wafer 10 are shown. Figure 32 It's equivalent to cutting off near the center. Figure 33 The image shows a vertical cross-sectional view of the first wafer. Figure 33 As shown, the shape of the first electrode pattern PA formed on the main surface 10b of the bare wafer 10 can be compared with a reference. Figure 3 The examples used are the same. Regarding... Figure 3 In the example shown, the first electrode pattern PA is formed on a flat surface, and here the first electrode pattern PA extends all the way to the outside of the recess 10g. That is, here, the first electrode pattern PA crosses the outer edge of the recess 10g and extends from the inside of the recess 10g to the outside of the recess 10g.

[0173] By forming a recess 10g on the bare wafer 10, and subsequently forming the first electrode pattern PA, as shown, was obtained. Figure 32 and Figure 33 The upper wafer 10WB shown is the first wafer. In this example, the metal layer 11x surrounding the first electrode pattern PA is also formed on the main surface 10b.

[0174] (5-2. Step S2 to obtain a laminate with an internal cavity)

[0175] After obtaining the upper wafer 10WB as the first wafer, according to Figure 1 and Figure 28 The steps shown can be used to complete a curved surface support structure. That is, firstly, as... Figure 34 As shown, an upper wafer 10WB is stacked on a lower wafer 20WA with the first electrode pattern PA facing the second electrode pattern PB, and the upper wafer 10WB and the lower wafer 20WA are bonded together. By bonding the upper wafer 10WB and the lower wafer 20WA, a stack 30B composed of these wafers is obtained.

[0176] At this point, the metal layer 11x of the upper wafer 10WB and the metal layer 12x of the lower wafer 20WA are bonded, and the portion of the first electrode pattern PA located on the island portion 10h is bonded to the portion of the second electrode pattern PB located on the island portion 20h. As a result, as... Figure 34 As shown, a roughly annular cavity 30cb is formed by the recess 10g on the upper wafer 10WB side and the recess 20g on the lower wafer 20WA side. As mentioned above, the bonding of the upper wafer 10WB and the lower wafer 20WA can be performed at a pressure below atmospheric pressure.

[0177] (5-3. Step S3: Deformation of the first wafer and / or the second wafer by heating)

[0178] Next, by heating, the pressure difference between the inside of cavity 30cb and the outside of the laminate 30B is used to deform one or both of the upper wafer 10WB and the lower wafer 20WA. For example, a fixture with holes is placed on the upper wafer 10WB, and the laminate 30B is heated while a vacuum is being created. Figure 35 In the example shown, a fixture 50 is disposed on another main surface 10a opposite the main surface 10b on which the first electrode pattern PA is formed. Figure 35 It can be seen that the opening of the hole 50h of the fixture 50 is located on the outer side of the recess 10g of the upper wafer 10WB.

[0179] It goes without saying that any of the aforementioned jigs 51, 53, 54, and 56 can be used instead of jig 50. The holes provided on the jig are not limited to cylindrical shapes; they can also be annular, like the holes 53h in jig 53 and 54h in jig 54.

[0180] Here, in the upper wafer 10WB and the lower wafer 20WA constituting the laminate 30B, a portion of the upper wafer 10WB is selectively deformed. Figure 36 The laminate 30B after deformation of the upper wafer 10WB is shown. By deforming the upper wafer 10WB to make the external pressure of the laminate 30B lower than the internal pressure of the cavity 30cb, the portion inside the hole 50h of the fixture 50 bulges upward, thereby obtaining the cavity 30t from the cavity 30cb. For example, by making the internal pressure of the cavity 30cb lower than atmospheric pressure and keeping the pressure difference between the inside of the cavity 30cb and the outside of the laminate 30B within a predetermined range, the probability of the first electrode pattern PA being broken due to deformation of the upper wafer 10WB can be advantageously reduced, as in the examples described so far.

[0181] exist Figure 36 In the example shown, as referenced Figure 16 As illustrated in the example, angular shapes also appeared on the main surface 10b of the upper wafer 10WB. Figure 36 (Sb1 and Sb2 are indicated by dashed circles). However, since these angular shapes were generated during the deformation of the flat wafer 10WA in the examples described so far, in this example, these corners are formed by creating recesses 10g on the bare wafer 10, existing before the formation of the first electrode pattern PA. That is, in this example, the extreme stretching and near-right-angle bending of the conductive layer of the first electrode pattern PA due to the deformation of the upper wafer 10WB can be avoided, thus reducing the probability of faults such as wire breaks in the first electrode pattern PA. This effect can also be expected in applications such as... Figure 37 As shown in the example, instead of using a fixture with holes, a metal film 52 is formed on the laminate 30B to obtain a hemispherical shape such as a dome 14A.

[0182] (5-4. Step S4 in forming the harmonic oscillator)

[0183] After obtaining the shape of the dome 14A, the jig 50 is removed from the stack 30B. Using laser ablation or etching, a portion of the upper wafer 10WB is removed in a ring-like pattern, centered on the columnar portion 12 (see reference). Figure 22 Based on this, a resonator 10A can be formed from the upper wafer 10WB. Then, by removing the unwanted portions from the lower wafer 20WA, a resonator 10A can be obtained. Figure 23The example shown is the same gyroscope 1A.

[0184] According to embodiments of the present invention, electrode patterns can be reliably formed on three-dimensional structures such as the housing of a hemispherical resonator gyroscope using existing, uncomplicated, and inexpensive processing steps. Embodiments of the present invention are particularly advantageous for manufacturing processes where electrode patterns are formed on two-dimensional structures such as quartz wafers, and then curved support structures are obtained through wafer deformation. Since the subsequent process of forming electrodes on the three-dimensional structure can be eliminated, the manufacturing method of the present invention offers advantages not only in manufacturing cost but also in mass production. For example, in addition to forming curved support structures one wafer at a time, multiple (e.g., dozens to hundreds) curved support structures can be formed simultaneously on a single wafer.

Claims

1. A method for manufacturing a curved surface support structure, characterized in that, include: Step (a) of preparing a first wafer having a first electrode pattern including a first electrode; Step (b) is to obtain a laminate having an annular cavity inside by bonding the first wafer to a second wafer having a second electrode pattern containing a plurality of second electrodes. Step (c) involves heating the cavity and using the pressure difference between the cavity and the outside of the laminate to deform the surface of at least one of the first wafer and the second wafer into a curved shape, thereby increasing or decreasing the cavity volume. as well as Step (d) involves removing a portion of the first wafer along a circumference concentric with the annular band, thereby forming a resonator whose central portion is supported by the second wafer from the first wafer. Step (a) includes step (a1) of obtaining the first wafer by forming the first electrode pattern on one main face side of the bare wafer. In step (b), the first electrode and the second electrode in the laminate are positioned opposite each other with a spacing between them. Step (b) includes electrically connecting the first electrode to the second electrode pattern of the second wafer.

2. The manufacturing method as described in claim 1, wherein, The step (a1) includes forming either a bottom layer as the first electrode pattern or a conductive layer as the first electrode pattern by sputtering.

3. The manufacturing method as described in claim 1 or claim 2, wherein, Step (a) further includes step (a2) of forming an annular recess on the main surface of the bare wafer prior to step (a1). In step (a1), the first electrode pattern extends beyond the outer edge of the recess from the interior of the recess to the exterior of the recess.

4. The manufacturing method as described in claim 1 or claim 2, wherein, In step (c), the pressure inside the cavity is above 0.1 atmospheres and below 0.5 atmospheres.

5. The manufacturing method as described in claim 4, wherein, Step (b) includes bonding the first wafer and the second wafer under reduced pressure.

6. The manufacturing method as described in claim 1 or claim 2, wherein, Between step (b) and step (c), there is also a step (e) of placing a fixture with a hole having rounded corners on another main surface of the first wafer. Step (c) includes deforming a portion of the other main facet of the first wafer into a shape that mimics the opening shape of the fixture.

7. The manufacturing method as described in claim 6, wherein, The fixture has a protrusion located at the center of the hole, the protrusion having a front end with rounded corners.

8. The manufacturing method as described in claim 1 or claim 2, wherein, The harmonic oscillator includes: The columnar portion extending upward from the second wafer; and The edge portion is arranged in a ring around the columnar portion.

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