Method for manufacturing a micro-vibrator having a three-dimensional curved surface shape

Abstract

To provide a micro vibrator excellent in surface smoothness and capable of controlling a shape and thickness distribution of a three-dimensional curved surface portion.SOLUTION: A tabular reflow material 20 set on a die M having a recessed part M1 so as to cover the recessed part M1 is heated and softened by a heat source H2 arranged on a side opposite to the recessed part M1; the die M has a structure capable of performing at least one of heating and cooling a part of the die by at least one of a heat source H1 different from the heat source H2 and a cooling source; a micro vibrator capable of controlling a shape and thickness distribution of a three-dimensional curved surface portion by controlling temperature distribution of the reflow material 20 is obtained by performing at least one of heating and cooling the part of the die M when depressurizing the space of the recessed part M1 to deform the reflow material 20; and non-contact of the reflow material 20 to an inner wall and a bottom surface of the recessed part M1 when deforming the reflow material 20 can obtain the surface smoothness of the micro vibrator.SELECTED DRAWING: Figure 4C

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a microvibrator having a three-dimensional curved surface shape. body

Background Art

[0002] In recent years, the development of a microvibrator having a three-dimensional curved surface that can vibrate in a wine glass mode and a MEMS (Micro Electro Mechanical Systems) sensor including the same has been promoted. Examples of this type of MEMS sensor include a RIG (Rate Integrating Gyroscope) and a BRG (Bird-bath Resonator Gyroscope).

[0003] This microvibrator is formed by preparing a mold having a concave portion, setting a plate-shaped reflow material in the mold, heating and softening it, subjecting the concave portion to a pressure reduction treatment, and deforming the softened portion to form the shape of a three-dimensional curved surface (for example, Patent Document 1). Since the Q value representing the vibration state of this microvibrator reaches 10 6 or more, higher sensitivity than before is expected.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] ​The above-mentioned micro-vibrator heats one side of the reflow material from a heat source such as a blowtorch to soften the reflow material, and a three-dimensional curved surface shape is formed by controlling the pressure gradient using a mold. In a method like this, the micro-vibrator obtained through a process of deforming the softened reflow material along the concave portion of the mold while hardly contacting the concave surface of the mold has a very smooth surface and excellent surface smoothness.

[0006] In addition to the surface smoothness as described above, for this micro-vibrator to further improve the Q value, robustness, shock resistance, and vibration characteristics, it is desirable that the shape and thickness distribution of the three-dimensional curved surface portion be controlled.

[0007] However, in the above method, the temperature distribution of the reflow material during the formation of the three-dimensional shape cannot be controlled, and the three-dimensional curved surface portion cannot be controlled to have an arbitrary shape and thickness distribution.

[0008] In view of the above points, the present invention aims to provide a manufacturing method of a micro-vibrator with excellent surface smoothness and controlled shape and thickness distribution of the three-dimensional curved surface portion. body

Means for Solving the Problem

Means for Solving the Problem

[0009] To achieve the above object, the manufacturing method of the micro-vibrator described in claim 1 、2 is a manufacturing method of a micro-vibrator (2) having a three-dimensional curved surface, which includes preparing a mold (M) having a concave portion (M1), setting a plate-shaped reflow material (20) on the mold, covering the concave portion with the reflow material, reducing the pressure in the space of the concave portion closed by the reflow material, using the surface of the reflow material facing the concave portion as the lower surface (20b) and the surface opposite to the lower surface as the upper surface (20a), heating and softening the reflow material from the upper surface side, and deforming the reflow material by reducing the pressure in the space of the concave portion. When deforming the reflow material, at least one of heating or cooling is performed on a part of the mold. Moreover, in the method for manufacturing a micro-vibrator according to claim 1, heating or cooling of a part of the mold is performed in a region of the mold where the reflow material does not contact. In the method for manufacturing a micro-vibrator according to claim 2, a part of the mold is a different heat capacity portion (M3) composed of a material having a different heat capacity from other parts of the mold.

[0010] In this method for manufacturing a micro-vibrator, a reflow material is set in a mold having a recess, the reflow material is heated and softened, the reflow material is deformed by reducing the pressure in the recess space, and at least one of heating or cooling is performed on a part of the mold. By performing at least one of heating or cooling on a part of the mold during the molding of the reflow material, it becomes possible to control the temperature distribution in the reflow material, and the shape and thickness distribution of the three-dimensional curved surface can be controlled. Also, at this time, since the reflow material hardly contacts the surface of the recess of the mold, it is possible to manufacture a micro-vibrator in which the shape and thickness distribution of the three-dimensional curved surface part are controlled while ensuring surface smoothness.

[0011] Claim 5 The method for manufacturing a micro-vibrator according to claim [claim number not provided] is a method for manufacturing a micro-vibrator (2) having a three-dimensional curved surface, comprising preparing a mold (M) having a recess (M1), setting a plate-shaped reflow material (20) in the mold, covering the recess with the reflow material, reducing the pressure in the space of the recess closed by the reflow material, taking the surface of the reflow material facing the recess as the lower surface (20b) and the surface opposite to the lower surface as the upper surface (20a), heating and softening the reflow material from the upper surface side, and deforming the reflow material by reducing the pressure in the recess space. In deforming the reflow material, a mold having a different heat capacity part (M3) in which a part is made of a material having a different heat capacity from other parts of the mold is used to generate a temperature gradient in the mold.

[0012] In this method for manufacturing a micro-vibrator, a reflow material is set in a mold having a recess, the reflow material is heated and softened, and the reflow material is deformed by reducing the pressure in the recess space. Also, as the mold, a mold having a different heat capacity part in which a part is made of a material having a different heat capacity from other parts of the mold is prepared, and a temperature gradient in the mold is generated when deforming the reflow material. Thereby, it becomes possible to control the temperature distribution in the reflow material, the shape and thickness distribution of the three-dimensional curved surface are controlled, and since the reflow material hardly contacts the surface of the recess of the mold, it is possible to manufacture a micro-vibrator in which surface smoothness is ensured.

[0015] Note that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 5A

Figure 5B

Figure 5C

Figure 5D

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are identical or equivalent to each other will be described with the same reference numerals.

[0018] (First Embodiment) The first embodiment will be described with reference to the drawings. The micro-vibrator 2 according to this embodiment has, for example, a site of a substantially hemispherical three-dimensional curved surface and is a thin film member that can vibrate in a wine glass mode. The micro-vibrator 2 can be used in various MEMS devices that utilize vibration characteristics such as gyro sensors. Hereinafter, the case where the micro-vibrator 2 according to the embodiment is used in the inertial sensor 1 will be described as a representative example, but the structure and application of the micro-vibrator 2 are not limited.

[0019] 〔Inertial Sensor〕 An example of the inertial sensor 1 having the micro-vibrator 2 will be briefly described with reference to FIGS. 1 to 3.

[0020] Hereinafter, for convenience of explanation, as shown in FIG. 1, the direction along the left-right direction on the paper surface will be referred to as the "x direction", the direction orthogonal to the x direction on the same paper surface will be referred to as the "y direction", and the normal direction to the xy plane will be referred to as the "z direction", respectively. The x, y, and z directions in the figures after FIG. 2 respectively correspond to the x, y, and z directions in FIG. 1. Also, in this specification, "up" means the direction along the z direction in the figure and means the arrow side, and "down" means the opposite side of up. Further, in this specification, for example, as shown in FIG. 1, the state of viewing the inertial sensor 1 from the upper side in the z direction may be referred to as "top view".

[0021] The inertial sensor 1 has, for example, as shown in FIG. 1, a micro-vibrator 2 and a mounting substrate 3, and the micro-vibrator 2 is joined to the mounting substrate 3. The inertial sensor 1 is, for example, a gyro sensor, and is configured to detect the angular velocity applied to the inertial sensor 1 based on the change in capacitance between the thin micro-vibrator 2 and a plurality of electrode portions 53 described later in the mounting substrate 3.

[0022] The micro-vibrator 2 has, for example, as shown in FIGS. 1 and 2, a curved surface portion 21 having an outer shape of a substantially hemispherical three-dimensional curved surface, and a concave portion 22 recessed from the apex portion of the substantially hemispherical curved surface portion 21 toward the center side of the virtual hemisphere forming the outer surface of the curved surface portion 21. The micro-vibrator 2 has, for example, a bowl-shaped three-dimensional curved surface for the curved surface portion 21, and the Q value of its vibration is 10 6 or more. For the micro-vibrator 2, for example, a rim 211, which is an end portion of the curved surface portion 21 opposite to the concave portion 22, has a substantially cylindrical shape. When the micro-vibrator 2 is mounted on the mounting substrate 3, for example, the surface 2a side faces a plurality of electrode portions 53 (to be described later) on the mounting substrate 3, and the intervals between the plurality of electrode portions 53 are equally spaced. As shown in FIGS. 2 and 3, for the micro-vibrator 2, the curved surface portion 21 including the rim 211 is in a hollow state where it does not contact other members, and is in a state where it can vibrate in a wine glass mode.

[0023] For the micro-vibrator 2, as shown in FIG. 3, for example, the surface with the larger outer diameter is the front surface 2a, and the opposite surface is the back surface 2b. The bottom surface of the concave portion 22 in the Z direction on the back surface 2b side is the mounting surface 22b joined to the mounting substrate 3. For the micro-vibrator 2, for example, the bottom surface of the concave portion 22 in the Z direction on the front surface 2a side is the suction surface 22a used for conveyance when mounting on the mounting substrate 3. When the micro-vibrator 2 is mounted on the mounting substrate 3, the curved surface portion 21 including the rim 211 is in a hollow state where it does not contact other members, and the hollow rim 211 has a structure that vibrates in a wine glass mode. The conductive layer 23 is composed of, for example, but not limited to, a laminated film of Cr (chromium) or Ti (titanium) from the base side and an arbitrary conductive material such as Au (gold) or Pt (platinum), and functions as an electrode film. The conductive layer 23 is formed on the front surface 2a and the back surface 2b of the micro-vibrator 2 by an arbitrary vacuum film forming method such as sputtering or vapor deposition.

[0024] The micro-vibrator 2 is made of a reflow material such as quartz, glass, or Si (silicon) that softens when heated. For example, the micro-vibrator 2 is formed by processing a plate-shaped reflow material into a three-dimensional curved surface shape and is a thin member on the order of micrometers with a thickness of 100 μm or less. For example, with the direction along the thickness direction of the mounting substrate 3 taken as the height direction, the micro-vibrator 2 has a millimeter-sized shape with a height direction dimension of 2.5 mm and an outer diameter on the surface 2a side of the rim 211 of 5 mm. Further, the micro-vibrator 2 is formed using a reflow material, and the surface 2a of the curved surface portion 21 that does not contact the mold described later is smooth (for example, the surface roughness Ra is 1 nm or less). Note that the manufacturing method of the micro-vibrator 2 will be described later.

[0025] As shown in FIG. 1 for example, the mounting substrate 3 includes a lower substrate 4 and an upper substrate 5, and these are joined together. For example, the mounting substrate 3 is obtained by anodic bonding an upper substrate 5 made of Si, a semiconductor material, to a lower substrate 4 made of borosilicate glass, an insulating material.

[0026] The lower substrate 4 includes, for example, an annular etching groove 41 and a bridge wiring 42 that is arranged to straddle the etching groove 41 and is made of a conductive material such as Al (aluminum). The etching groove 41 is formed, for example, by wet etching using buffered hydrofluoric acid. The bridge wiring 42 is formed, for example, by a lift-off method using film formation by sputtering of Al. The bridge wiring 42 is arranged to pass between a plurality of electrode portions 53 and is electrically independent of the plurality of electrode portions 53. As shown in FIG. 2 for example, one end of the bridge wiring 42 is covered by the outer frame portion 54, and the other end on the opposite side is covered by the inner frame portion 51, and these serve to electrically connect them to the same potential.

[0027] The upper substrate 5 includes, for example, a frame-shaped inner frame portion 51, a plurality of electrode portions 53 that are arranged separately from each other so as to surround the inner frame portion 51, and a frame-shaped outer frame portion 54 that is arranged so as to surround the electrode portions 53. The portion of the mounting substrate 3 surrounded by the inner frame portion 51 is a bonding region with the micro-vibrator 2, and the bonding member 52 is arranged therein. The bonding member 52 is, for example, a conductive material made of a conductive material such as AuSn (gold-tin), Ag (silver), or Au. The upper substrate 5 is, for example, a Si substrate, and after being anodically bonded to the lower substrate 4 having the etching groove 41 and the bridge wiring 42, it has a configuration partitioned into regions of the inner frame portion 51, the plurality of electrode portions 53, and the outer frame portion 54 by trench etching such as DRIE. Note that DRIE is an abbreviation for Deep Reactive Ion Etching.

[0028] The inner frame portion 51 has, for example, an annular shape in a top view. As shown in, for example, FIGS. 2 and 3, the outer diameter and the inner diameter of the inner frame portion 51 are sized so as not to contact the micro-vibrator 2.

[0029] The plurality of electrode portions 53 are arranged separately from each other so as to surround the inner frame portion 51 at positions on the outer peripheral side of the etching groove 41. For example, as shown in FIG. 1, the plurality of electrode portions 53 have a configuration in which an annulus surrounding the inner frame portion 51 is evenly divided at predetermined intervals in a top view. As shown in, for example, FIG. 3, electrode films 531 are formed on the upper surfaces of the plurality of electrode portions 53, and wires (not shown) are connected to the electrode films 531. Thereby, the plurality of electrode portions 53 are electrically connected to an external circuit board or the like (not shown), and the potential can be controlled. As shown in FIGS. 1 and 3, when the micro-vibrator 2 is mounted, all of the plurality of electrode portions 53 are spaced apart from the rim 211 of the micro-vibrator 2 by a predetermined distance, and each forms a capacitor with the micro-vibrator 2. That is, the mounting substrate 3 can detect the capacitance between the mounting substrate 3 and the micro-vibrator 2, generate an electrostatic attraction between the mounting substrate 3 and the micro-vibrator 2, and vibrate the micro-vibrator 2 in a wine glass mode via the plurality of electrode portions 53.

[0030] The outer frame portion 54 has a frame shape that surrounds the inner frame portion 51 in a top view. For example, as shown in FIG. 2, it is provided with an electrode film 541 made of Al or the like on the top surface. A wire (not shown) is connected to the electrode film 541 of the outer frame portion 54, and by being electrically connected to an external circuit board or the like (not shown), the potential of the outer frame portion 54 can be controlled by an external power source or the like (not shown). The outer frame portion 54 is electrically connected to the micro-vibrator 2 via the bridge wiring 42, the inner frame portion 51, and the joining member 52. In other words, the mounting substrate 3 can adjust the potential of the micro-vibrator 2 by adjusting the potential of the outer frame portion 54.

[0031] Note that the configuration, shape, etc. of the micro-vibrator 2 and the mounting substrate 3 are not limited to the examples shown in FIGS. 1 to 3 and can be appropriately changed. Further, the mounting substrate 3 is, for example, mounted in a vacuum environment with a vacuum degree of a predetermined value or less so that a cap member (not shown) does not contact the micro-vibrator 2, and the micro-vibrator 2 is hermetically sealed in a vacuum.

[0032] The above is the basic configuration of the inertial sensor 1.

[0033] 〔Manufacturing method of micro-vibrator〕 Next, the manufacturing method of the micro-vibrator 2 of the present embodiment will be described with reference to FIGS. 4A to 4D.

[0034] First, as shown in FIG. 4A for example, a plate-shaped reflow material 20 and a mold M for forming a three-dimensional curved surface shape are prepared. Examples of the plate-shaped reflow material 20 include a quartz plate, etc., and it is arranged so as to cover the entire concave portion M1 of the mold M described later.

[0035] The mold M is made of any material or composite material that has higher heat resistance than the reflow material 20, for example. The mold M includes, for example, a recess M1 that serves as a space when forming a three-dimensional curved surface shape in the reflow material 20. Further, the mold M includes, for example, at the center of the recess M1, a columnar support portion M2 that protrudes along the depth direction of the recess M1 toward the upper end of the recess M1 and supports a part of the reflow material 20 during processing. The mold M has a through hole M11 formed in the bottom surface of the recess M1, and by being attached to a vacuum mechanism (not shown), it is configured to be able to decompress the space of the recess M1 blocked by the reflow material 20 through the through hole M11. Further, the mold M incorporates a first heat source H1, and it is possible to heat a part of the mold M when the reflow material 20 is softened / molded by an external second heat source H2 described later. The first heat source H1 is, for example, an electric heater or a Peltier element, etc., and is disposed at the upper end of the recess M1 in the mold M at a position that contacts the reflow material 20.

[0036] Note that the "upper end of the recess M1" mentioned above means the end portion of the inner wall of the recess M1 on the side opposite to the through hole M11. Further, hereinafter, for convenience of explanation, the surface of the outer surface of the reflow material 20 on the side opposite to the recess M1 is referred to as the "upper surface 20a", and the surface facing the recess M1 is referred to as the "lower surface 20b".

[0037] And a second heat source H2 is disposed on the upper surface 20a side of the reflow material 20, and the reflow material 20 is heated and softened by the second heat source H2. For example, as shown in FIG. 4B, the reflow material 20 is heated and softened by the second heat source H2. The second heat source H2 is, for example, a flame from a torch, but is not limited to this, and any heating method such as radiation, radiation, heat conduction, convection, or induction heating may be adopted as long as it can heat and soften the reflow material 20. When the reflow material 20 is a quartz plate, for example, the reflow material 20 is heated to a temperature of 1600°C to 1800°C by the second heat source H2. This heating temperature is appropriately changed according to the softening point, thickness, dimensions, etc. of the reflow material 20.

[0038] When heating and softening the reflow material 20, evacuation is performed on the space formed by the concave portion M1 of the mold M and the reflow material 20 through the through hole M11 by a vacuum mechanism (not shown). For the evacuation, for example, it is performed so that the degree of vacuum in the concave portion M1 becomes about 0.25 atm (about 253 hPa). However, the decompression conditions are appropriately changed according to the shape of the final micro vibrator 2 and the like. As a result, the softened portion of the reflow material 20 has its lower surface 20b side stretched toward the bottom surface of the concave portion M1, and its central peripheral region is supported by the support portion M2. As a result, the reflow material 20 is formed with a curved surface portion 201 having a substantially hemispherical three-dimensional curved surface shape and a concave portion 202 recessed near the center of the curved surface portion 201 by being supported by the support portion M2. Further, in the reflow material 20, the portion located outside the concave portion M1 is located at the outer peripheral end of the curved surface portion 201 and becomes a flat end portion 203.

[0039] Also, at this time, the first heat source H1 of the mold M is operated to heat a part of the mold M (for example, the part in contact with the reflow material 20) to generate a temperature gradient in the mold M. This is to control the temperature distribution during the molding of the reflow material 20 and to control the thickness and shape of the curved surface portion 201 and the concave portion 202.

[0040] If the first heat source H1 is not operated, for example, as shown in FIG. 4B, the reflow material 20 may become an overhang portion 204 in which the boundary portion between the curved surface portion 201 and the end portion 203 protrudes toward the center of the concave portion M1. This is because the portion of the reflow material 20 in contact with the mold M and the portion adjacent thereto have a lower temperature than the portion that becomes a hollow state away from the mold M, and the fluidity is lower than that of the portion with a higher temperature.

[0041] Here, in the above heat forming, although the portion of the reflow material 20 that does not contact the mold M (the curved surface portion 201) has excellent surface smoothness (for example, the surface roughness Ra is 1 nm or less), it cannot reflect the shape of the inner wall and the bottom surface of the concave portion M1 of the mold M. As a result of the intensive studies by the present inventors, it has been found that by controlling the temperature distribution of the reflow material 20 during the heat forming of the reflow material 20, the shape and thickness of the curved surface portion 201 of the reflow material 20 can be controlled. Regarding the portion of the reflow material 20 with a high temperature, the thickness tends to be relatively thin, and regarding the portion with a low temperature, the thickness tends to be relatively thick. And the present inventors have found that temperature control of the mold M during the heat forming is effective as a method for controlling the temperature distribution during the heat forming of the reflow material 20.

[0042] Specifically, for example, using a mold M incorporating a first heating source H1, during the heat forming of the reflow material 20, a part of the mold M is heated by the first heating source H1 to generate a temperature gradient in the mold M. More specifically, for example, as shown in FIG. 4C, a part of the mold M is heated by the first heating source H1 disposed at the position of the upper end of the concave portion M1 of the mold M and in the region where it contacts the reflow material 20. Thereby, the temperature drop of the portion of the reflow material 20 located at the boundary between the curved surface portion 201 and the end portion 203 is suppressed, and a shape without an overhang portion 204 is obtained.

[0043] Note that the heating by the first heating source H1 is performed, for example, such that the first heating source H1 is 1600°C to 1800°C when the first heating source H1 is a heater and the reflow material 20 is a quartz plate, but it can be appropriately changed according to the thickness, material, etc. of the reflow material 20. Also, in the above, for the sake of convenience of explanation, an example in which the first heating source H1 is operated during the heat forming of the reflow material 20 to heat a part of the mold M has been described, but it is not limited thereto. For example, the first heating source H1 may be operated simultaneously with or before the second heating source H2 before the overhang portion 204 as shown in FIG. 4B occurs.

[0044] Subsequently, the concave portion M1 of the mold M is returned to normal pressure, the processed reflow material 20 is removed, and the reflow material 20 is sealed with a sealing material E made of an arbitrary curable resin material, for example, as shown in FIG. 4D. Then, for example, polishing and CMP are performed on the surface of the sealing material E close to the end portion 203, and the end portion 203 together with the sealing material E is removed. As a result, the reflow material 20 has a shape having a curved surface portion 21 of an annular curved surface and a concave portion 22 recessed from the curved surface portion 21. Note that CMP is an abbreviation for Chemical Mechanical Polishing.

[0045] Then, the sealing material E is completely removed by any method such as heating or dissolution using a chemical solution, and the reflow material 20 is taken out. Finally, for example, a conductive layer 23 is formed on the front and back surfaces of the processed reflow material 20 by any film forming process such as sputtering, evaporation, atomic layer deposition (ALD), or chemical vapor deposition (CVD).

[0046] Note that the micro-vibrator 2 is manufactured by, for example, the above-described manufacturing process, and has a substantially half-toroidal shape that is rotationally symmetric about the Z direction as the rotation axis. However, any shape that can vibrate in the wine glass mode may be used, and the shape is not limited to the illustrated shape. In addition, a gyro sensor in which the micro-vibrator 2 having the illustrated shape is mounted on the mounting substrate 3 is also referred to as a BRG (abbreviation for Bird-bath Resonator Gyroscope).

[0047] According to the present embodiment, by setting the reflow material 20 in the mold M having the concave portion M1, heating and softening the reflow material 20, reducing the pressure in the space of the concave portion M1, and deforming the reflow material 20 without bringing it into contact with the inner wall and bottom surface of the concave portion M1, the surface smoothness of the curved surface portion 201 can be ensured. Further, by heating a part of the mold M with the first heat source H1, it becomes possible to control the temperature distribution in the reflow material 20 during the thermoforming of the reflow material 20, and the shape and thickness distribution of the three-dimensional curved surface can be controlled. As a result, a micro-vibrator 2 in which the shape and thickness distribution of the three-dimensional curved surface portion are controlled while ensuring the surface smoothness can be obtained.

[0048] This micro-vibrator 2 can be configured such that, for example, the temperature variation of the reflow material 20 in the molding process is smaller than that in a method (hereinafter referred to as "comparative example") where a part of the mold M is not heated, and the thickness variation is suppressed. For example, in the comparative example, when the thickness of the thinnest part of the curved surface portion 201 is about 10 μm, the thickness of the thickest part is about 100 μm. In contrast, in the method of this embodiment, a micro-vibrator 2 with a thickness of about 20 to 50 μm can be obtained for both the thinnest part and the thickest part. For example, the micro-vibrator 2 can be made more uniform than the comparative example in such a way that, by heating a part of the mold M, taking the thickness of the thickest part of the curved surface portion 21 as t1 and the thickness of the thinnest part as t2, t1 is 100 μm or less, and t2 / t1 is 0.4 or more. Such a micro-vibrator 2 with controlled thickness distribution can be controlled so that the resonance frequency becomes a desired value, and by making the thickness closer to being uniform than in the comparative example, an improvement in impact resistance, vibration resistance, and robustness can also be expected.

[0049] (Second Embodiment) The second embodiment will be described with reference to FIGS. 5A to 5D.

[0050] The micro-vibrator 2 of this embodiment is formed, for example, as shown in FIGS. 5A to 5D, by heating or cooling at least a part of the mold M by at least one of the first heating source H1 or the cooling source C1 built into the mold M, and has a configuration without the recess 22. The micro-vibrator 2 of this embodiment is different from the first embodiment in the above points. In this embodiment, this difference will be mainly described.

[0051] In this embodiment, the mold M for manufacturing the micro-vibrator 2 has no support column M2 as shown in, for example, FIG. 5A, and the built-in first heat source H1 is arranged on the bottom surface side of the recess M1. That is, the mold M is configured such that, during the thermoforming of the reflow material 20, a part of the mold M that does not contact the reflow material 20 can be heated and does not support the softened portion of the reflow material 20. In this case, as shown in, for example, FIG. 5B, the reflow material 20 has an overhang portion 204 formed, and a portion of the curved surface portion 201 close to the first heat source H1 bulges more than the upper end side of the recess M1, so-called "bottom swelling" shape. This is presumably because the temperature of the portion of the reflow material 20 close to the first heat source H1 is less likely to decrease, ensuring fluidity during thermoforming. Such a shape of the reflow material 20 can be obtained, for example, when the reflow material 20 is a quartz plate, by controlling the temperature of the first heat source H1 to about 800°C while heating the reflow material 20 to about 1600°C by the second heat source H2. Then, by removing the end portion 203 by CMP or the like as in the first embodiment, the micro-vibrator 2 has a configuration in which the curved surface portion 201 with a bottom swelling shape becomes the curved surface portion 21 and does not have a portion corresponding to the recess 22.

[0052] The mold M may have a configuration in which a cooling source C1 is built in instead of the first heat source H1, as shown in, for example, FIG. 5C. The cooling source C1 is, for example, a cooling mechanism having a cooling pipe (not shown) capable of flowing a refrigerant such as water, or a Peltier element. In this case, the reflow material 20 has an overhang portion 204 formed, and a portion of the curved surface portion 201 close to the cooling source C1 shrinks more than the upper end side of the recess M1, so-called "bottom shrinkage" shape. This is presumably because the temperature of the portion of the reflow material 20 close to the cooling source C1 decreases more, suppressing fluidity during thermoforming. Such a shape of the reflow material 20 can be obtained, for example, when the reflow material 20 is a quartz plate, by controlling the temperature of the cooling source C1 to about 100°C while heating the reflow material 20 to about 1600°C by the second heat source H2.

[0053] As shown in, for example, FIG. 5D, the mold M may be configured to incorporate both a first heating source H1 and a cooling source C1, and to be able to heat a part of the mold M while cooling a part different from the said part. For example, in the mold M, the first heating source H1 is arranged on the upper end side of the inner wall of the concave portion M1, and the cooling source C1 is arranged on the bottom surface side. In this case, the formation of the overhang portion 204 of the reflow material 20 is suppressed by the heating of the first heating source H1, and the portion of the curved surface portion 201 close to the cooling source C1 becomes a shape of "bottom shrinkage" in which it is shrunk more than other portions. This is presumably because, during thermoforming, the fluidity of the portion of the reflow material 20 close to the first heating source H1 is ensured, while the fluidity of the portion close to the cooling source C1 is suppressed. Such a shape of the reflow material 20 can be obtained, for example, when the reflow material 20 is a quartz plate, by heating the reflow material 20 to about 1600° C. with the second heating source H2, and controlling the temperature of the first heating source H1 to about 800° C. and the temperature of the cooling source C1 to about 100° C.

[0054] Note that the microvibrator 2 may be configured to have a joint portion (for example, a columnar quartz member) for joining to other members such as the mounting substrate 3 after the process shown in FIG. 5B, FIG. 5C or FIG. 5D, by joining the joint portion to the inner wall side of the curved surface portion 201. Also, the arrangement relationship of the first heating source H1 and the cooling source C1 in the mold M can be appropriately changed according to the thickness, shape, etc. of the microvibrator 2 that is finally desired to be obtained.

[0055] Also according to the present embodiment, the microvibrator 2 that obtains the same effects as those of the above-described first embodiment is obtained. Further, in the present embodiment, the following effects are also obtained.

[0056] (1) In the comparative example where only the reflow material 20 is heated by the second heat source H2, it is possible to manufacture the micro-vibrator 2 having a configuration with a partially different shape such as the above-described bottom bulge or bottom depression. Further, for this micro-vibrator 2, with the direction along the depth direction of the concave portion M1 in the curved surface portion 21 (the portion that was the curved surface portion 201) as the height direction, it becomes possible to control the thickness distribution in the height direction to a desired one. For example, in the manufacturing method of the comparative example, the portion of the reflow material 20 close to the through-hole M11 of the mold M becomes thinner than other portions, but when the shape of the bottom depression is formed by the manufacturing method according to the present embodiment, the thickness of the depressed portion can be increased. In this way, by intentionally changing the thickness in the height direction of the micro-vibrator 2, that is, the thickness between the portion mainly vibrated in the wine glass mode and the other portion, it becomes possible to control the main resonance frequency.

[0057] (Third Embodiment) The third embodiment will be described with reference to FIGS. 6 and 7.

[0058] The micro-vibrator 2 of the present embodiment uses, for example, as shown in FIG. 6, a mold M in which a part of the mold M is a different heat capacity portion M3 having a different heat capacity from other portions of the mold M, and is formed in a state where a temperature gradient is generated in the mold M during thermoforming, and has a configuration without the concave portion 22. The micro-vibrator 2 of the present embodiment is different from the first embodiment in the above points. In the present embodiment, this difference will be mainly described.

[0059] In this embodiment, the mold M for manufacturing the micro-vibrator 2 has no support column portion M2, for example, as shown in FIG. 6, and a part thereof is a different heat capacity portion M3 whose heat capacity is different from other parts. That is, when the reflow material 20 is heated and formed, a temperature gradient is generated in the mold M because the different heat capacity portion M3 of the mold M becomes a region where the temperature rises more easily or less easily than other parts of the mold M. And the mold M is configured not to support the softened part of the reflow material 20. For example, the mold M is configured such that a frame-shaped different heat capacity portion M3 along the opening of the recess M1 is disposed at the upper end of the recess M1 and in a region in contact with the reflow material 20.

[0060] For example, the main part of the mold M is a sintered body mainly composed of carbon, and the different heat capacity portion M3 is made of a metal material having higher thermal conductivity than the main part or a ceramic having lower thermal conductivity than the main part. In this embodiment, the mold M may be configured, for example, by a method of integrally forming the main part and the different heat capacity portion M3 after separately forming them, or may be integrally configured by a method of simultaneously sintering and forming the different heat capacity portion M3 during sintering of the main part. Also, the constituent materials of the main part and the different heat capacity portion M3, the arrangement of the different heat capacity portion M3, etc. are not limited to the above examples.

[0061] When the different heat capacity portion M3 is arranged at the upper end of the recess M1 and in a region in contact with the reflow material 20, and the different heat capacity portion M3 has a larger heat capacity than the main part, the reflow material 20 has, for example, the shape shown in FIG. 6. Specifically, as a result of the different heat capacity portion M3 having a higher temperature than other parts of the mold M, the temperature drop at the boundary between the curved surface portion 201 and the end portion 203 is suppressed, and the generation of the overhang portion 204 is suppressed.

[0062] Also, for example, as shown in FIG. 7, the mold M may be configured to incorporate a cooling source C1 in addition to the different heat capacity portion M3. In this case, the reflow material 20 has no overhang portion 204, and the curved surface portion 201 has a shape of bottom shrinkage.

[0063] Note that, after the process shown in FIG. 6 or FIG. 7, the micro-vibrator 2 may be configured to have a joint portion by joining the joint portion to the inner wall side of the curved surface portion 201 in the same manner as in the second embodiment. Further, the mold M may be configured to have the first heating source H1 in addition to the different heat capacity portion M3, or may be configured to have both the first heating source H1 and the cooling source C1. In this case, the arrangement relationship of the different heat capacity portion M3, the first heating source H1, and the cooling source C1 in the mold M can be appropriately changed according to the thickness, shape, etc. of the micro-vibrator 2 that is finally desired to be obtained.

[0064] Also according to this embodiment, a micro-vibrator 2 that can obtain the same effects as those of the first embodiment and the second embodiment can be manufactured.

[0065] (Other embodiments) Although the present disclosure has been described based on examples, it is understood that the present disclosure is not limited to such examples and structures. The present disclosure also includes various modifications and modifications within an equivalent range. In addition, various combinations and forms, and further other combinations and forms including only one, more, or less of those elements are also within the scope and spirit of the present disclosure.

[0066] (1) For example, in each of the above embodiments, the first heating source H1 may be arranged outside the mold M as shown in FIG. 8. In this case, the first heating source H1 is, for example, a torch, a heater, a lamp, a hot air generator, etc., and heats a part of the mold M from the outside. Similarly, the cooling source C1 may also be arranged outside the mold M. In this case, the cooling source C1 is, for example, a cold air generator, and cools a part of the mold M from the outside. Also, the arrangements of the first heating source H1 and the cooling source C1 when arranged outside can be appropriately changed.

[0067] (2) In each of the above embodiments, when the mold M has at least one of the first heat source H1 and the cooling source C1, an example where only one of them is built into the mold M or arranged outside the mold M has been described, but there may be two or more. In this case, a plurality of frame-shaped first heat sources H1 or cooling sources C1 may be arranged, or a plurality of piece-shaped first heat sources H1 or cooling sources C1 may be arranged so as to be scattered at multiple points.

[0068] (3) In the above third embodiment, an example where the mold M has one different heat capacity portion M3 has been described, but the mold M may have a configuration having a plurality of different heat capacity portions M3.

[0069] (4) In the above first embodiment, the case where the mold M has a configuration with the built-in first heat source H1 has been described as a representative example, but it is not limited thereto. For example, the mold M having the support portion M2 may have a configuration with a built-in cooling source C1 instead of the first heat source H1, or may have a configuration with both the first heat source H1 and the cooling source C1 built in.

[0070] (5) In the above second and third embodiments, an example where the mold M does not have the support portion M2 has been described, but the mold M may have a configuration with the support portion M2.

Explanation of reference numerals

[0071] 2 ··· Micro-vibrator, 2a ··· Surface, 2b ··· Back surface, 20 ··· Reflow material, 20a ··· Upper surface, 20b ··· Lower surface, 21 ··· Curved surface portion, 22 ··· (Recess of the micro-vibrator), M ··· Mold, M1 ··· (Recess of the mold), M2 ··· Support portion, M3 ··· Different heat capacity portion, C2 ··· Cooling source, H1 ··· Heat source

Claims

1. A method for manufacturing a micro-vibrator (2) having a three-dimensional curved surface, comprising: preparing a mold (M) having a recess (M1), setting a plate-shaped reflow material (20) in the mold, and covering the recess with the reflow material; reducing the pressure in the space of the recess closed by the reflow material; using the surface of the reflow material facing the recess as the lower surface (20b) and the surface opposite to the lower surface as the upper surface (20a), heating the reflow material from the upper surface side to soften it, and deforming the reflow material by reducing the pressure in the space of the recess; in deforming the reflow material, performing at least one of heating or cooling on a part of the mold; A method for manufacturing a micro-vibrator, wherein the heating or cooling of a part of the mold is performed in a region of the mold where the reflow material is not in contact.

2. A method for manufacturing a micro-vibrator (2) having a three-dimensional curved surface, comprising: preparing a mold (M) having a recess (M1), setting a plate-shaped reflow material (20) in the mold, and covering the recess with the reflow material; reducing the pressure in the space of the recess closed by the reflow material; using the surface of the reflow material facing the recess as the lower surface (20b) and the surface opposite to the lower surface as the upper surface (20a), heating the reflow material from the upper surface side to soften it, and deforming the reflow material by reducing the pressure in the space of the recess; in deforming the reflow material, performing at least one of heating or cooling on a part of the mold; A method for manufacturing a micro-vibrator, wherein a part of the mold is a different heat capacity part (M3) made of a material having a different heat capacity from other parts of the mold.

3. The method for manufacturing a micro-vibrator according to claim 1 or 2, wherein the heating or cooling of a part of the mold is performed by a heating source (H1) or a cooling source (C1) built in the mold.

4. The method for manufacturing a micro-vibrator according to claim 1 or 2, wherein the heating or cooling of a part of the mold is performed by a heating source (H1) or a cooling source (C1) disposed outside the mold.

5. A method for manufacturing a micro-vibrator (2) having a three-dimensional curved surface, comprising: preparing a mold (M) having a recess (M1), setting a plate-shaped reflow material (20) in the mold, and covering the recess with the reflow material; Reducing the pressure in the space of the recess blocked by the reflow material; Regarding the reflow material, the surface facing the recess is defined as the lower surface (20b), and the surface opposite to the lower surface is defined as the upper surface (20a). The reflow material is heated from the upper surface side to be softened, and the reflow material is deformed by reducing the pressure in the space of the recess, including: In deforming the reflow material, a mold having a different heat capacity portion (M3) in which a part of the mold is made of a material having a different heat capacity from other parts of the mold is used to generate a temperature gradient in the mold. A method for manufacturing a micro-vibrator.

6. The method for manufacturing a micro-vibrator according to any one of claims 1 to 5, wherein the mold has a support portion (M2) that protrudes from the bottom surface of the recess toward the opening and contacts a part of the softened reflow material.

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