JP2016144091A - Method for manufacturing vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibrator manufacturing method capable of reducing dispersion of frequencies.SOLUTION: The vibrator manufacturing method according to the invention includes: a step S1 for mounting a vibration piece on a substrate by a joint material; a step S4 for performing heat treatment of the joint material and the vibration piece at a first temperature; a step S5 for adjusting a frequency of the vibration piece after the step S4 for the heat treatment at the first temperature; and a step S6 for performing heat treatment of the joint material and the vibration piece at a second temperature after the step S5 for adjusting the frequency, where the second temperature is lower than the first temperature and a difference between the first temperature and the second temperature is 15°C or more.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a method for manufacturing a vibrator.

  2. Description of the Related Art Conventionally, vibrators manufactured by housing a resonator element using quartz in a package are known. Such a vibrator is widely used, for example, as a reference frequency source or an oscillation source for various electronic devices. In particular, a vibrator including a resonator element using a quartz crystal substrate cut at a cut angle called AT cut is widely used in mobile communication devices such as mobile phones.

  As a method for manufacturing such a vibrator, for example, Patent Document 1 discloses a first annealing step for curing a conductive adhesive and an outgas of a conductive adhesive that could not be sufficiently removed in the first annealing step. A second annealing step for discharging the components and eliminating the stress distortion of the vibrating piece; a frequency adjusting step for adjusting the frequency of the vibrator; and discharging the outgas component of the conductive adhesive and eliminating the stress distortion of the vibrating piece. A vibrator manufacturing method including a third annealing step is disclosed.

  According to the method for manufacturing a vibrator disclosed in Patent Document 1, by increasing the number of times of annealing as described above, the outgas component generated from the conductive adhesive adheres to the resonator element and inhibits frequency stability. In addition, the problem that the stress strain inherent in the resonator element is not sufficiently eliminated and the aging characteristic is destabilized is solved, and various characteristics of the vibrator are improved.

JP 2007-336320 A

  However, in the method for manufacturing the vibrator disclosed in Patent Document 1, in the third annealing step performed after the frequency adjustment step of the vibrator, chromium or the like constituting the base electrode layer of the excitation electrode of the vibrator element is heated. And may be deposited on the surface of gold constituting the main electrode layer. For example, when chromium is deposited on the surface of gold, there is a problem that the frequency of the vibrator fluctuates because the mass changes due to oxidation or hydroxylation of the deposited chromium.

  FIG. 17 is a cross-sectional view schematically showing the state of the excitation electrode in each manufacturing process of the conventional vibrator. FIG. 17A shows the excitation electrode in the initial state. FIG. 17B shows the state of the excitation electrode in the second annealing step. FIG. 17C shows the state of the excitation electrode in the frequency adjustment process. FIG. 17D shows the state of the excitation electrode in the third annealing step. Below, the excitation electrode demonstrates the case where the base layer (base electrode layer) 2 is comprised with chromium, and the upper layer (main electrode layer) 4 is comprised with gold | metal | money.

  As shown in FIG. 17A, the excitation electrode is formed by laminating the base layer 2 and the upper layer 4 in this order from the quartz substrate side.

  As shown in FIG. 17B, in the second annealing step, chromium in the underlayer 2 is diffused into the upper layer 4 by heat, and a chromium oxide layer 6 is formed on the surface of the upper layer 4. Therefore, the mass of the vibrating piece increases by the amount of oxygen.

  As shown in FIG. 17C, in the frequency adjusting step, the chromium oxide layer 6 and a part of the upper layer 4 are removed by ion milling that irradiates an ion laser or the like, and the mass of the resonator element is changed. Is adjusted.

  As shown in FIG. 17D, when heat at the same temperature as or higher than that in the second annealing step is applied in the third annealing step, chromium in the underlayer 2 diffuses again into the upper layer 4 and the upper layer A chromium oxide layer 6 is formed on the surface of 4. As a result, in the third annealing step, the mass of the resonator element increases by the amount of oxygen, and the frequency of the vibrator changes.

  As described above, in the conventional method for manufacturing a vibrator, the mass of the resonator element increases in the third annealing step after the frequency adjustment step and the frequency of the vibrator fluctuates. There was a problem that the dispersion of the large.

  One of the objects according to some aspects of the present invention is to provide a method for manufacturing a vibrator that can reduce variation in frequency.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
The method for manufacturing the vibrator according to this application example is as follows:
Mounting the resonator element on the substrate using a bonding material;
Heat-treating the bonding material and the resonator element at a first temperature;
Adjusting the frequency of the resonator element after the heat treatment at the first temperature;
After the step of adjusting the frequency, the step of heat-treating the bonding material and the resonator element at a second temperature;
Including
The second temperature is lower than the first temperature;
The difference between the first temperature and the second temperature is 15 ° C. or more.

  In such a vibrator manufacturing method, the second temperature is lower than the first temperature, and the difference between the first temperature and the second temperature is 15 ° C. or higher. The fluctuation of the frequency of the vibrator in the step of performing can be reduced. Therefore, according to such a method for manufacturing a vibrator, frequency variations can be reduced.

[Application Example 2]
In the method for manufacturing a vibrator according to this application example,
The first temperature is 215 ° C. or more and 320 ° C. or less,
The second temperature may be 200 ° C. or higher.

  In such a method for manufacturing a vibrator, as will be described later, it is possible to reduce a variation in frequency and obtain a vibrator having excellent aging characteristics.

[Application Example 3]
In the method for manufacturing a vibrator according to this application example,
The difference between the first temperature and the second temperature may be 30 ° C. or more.

In such a method for manufacturing a vibrator, as will be described later, frequency variations can be further reduced.

[Application Example 4]
In the method for manufacturing a vibrator according to this application example,
The second temperature may be 230 ° C. or higher.

  With such a method for manufacturing a vibrator, a vibrator having better aging characteristics can be obtained.

[Application Example 5]
In the method for manufacturing a vibrator according to this application example,
Before the step of heat-treating at the first temperature, a step of heat-treating the bonding material and curing the bonding material may be included.

  In such a method for manufacturing a vibrator, variation in frequency can be reduced.

[Application Example 6]
In the method for manufacturing a vibrator according to this application example,
The vibrating piece includes a quartz substrate and an excitation electrode,
The excitation electrode has a first layer formed on the quartz substrate, and a second layer formed on the first layer;
The first layer may be titanium, vanadium, chromium, niobium, tantalum, hafnium, molybdenum, nickel, zirconium, silver, aluminum, or an alloy containing these as a main component.

  In such a vibrator manufacturing method, in the step of performing the heat treatment at the second temperature, the diffusion of the material constituting the first layer of the excitation electrode can be reduced, and the material constituting the first layer can be oxidized or water. A change in mass due to oxidation or the like can be reduced. Therefore, fluctuations in the frequency of the vibrator in the process of heat treatment at the second temperature can be reduced. Therefore, according to such a method for manufacturing a vibrator, frequency variations can be reduced.

[Application Example 7]
In the method for manufacturing a vibrator according to this application example,
The second layer may be gold, platinum, or an alloy containing these as a main component.

  In such a method for manufacturing a vibrator, variation in frequency can be reduced.

[Application Example 8]
In the method for manufacturing a vibrator according to this application example,
The bonding material may be a silicone-based conductive adhesive.

  In such a vibrator manufacturing method, it is possible to suppress a change in the state of the conductive adhesive in the step of performing the heat treatment at the first temperature.

FIG. 1A is a cross-sectional view schematically showing the vibrator according to this embodiment, and FIG. 1B is a plan view schematically showing the vibrator according to this embodiment. FIG. 6 is a perspective view schematically showing a resonator element of the vibrator according to the embodiment. FIG. 3 is a plan view schematically showing a resonator element of the vibrator according to the embodiment. FIG. 3 is a cross-sectional view schematically showing a resonator element of the vibrator according to the embodiment. FIG. 3 is a cross-sectional view schematically showing a resonator element of the vibrator according to the embodiment. The perspective view which shows an AT cut quartz substrate typically. FIG. 3 is a cross-sectional view schematically showing a resonator element of the vibrator according to the embodiment. FIG. 3 is a cross-sectional view schematically showing an excitation electrode of the vibrator according to the embodiment. 5 is a flowchart showing an example of a method for manufacturing a vibrator according to the embodiment. Sectional drawing which shows typically the manufacturing process of the vibrator | oscillator which concerns on this embodiment. The graph which shows an example of the temperature change in the annealing furnace in an annealing process. Sectional drawing which shows typically the excitation electrode in each manufacturing process of a vibrator | oscillator. The graph which shows the relationship between annealing temperature and the time-dependent change of the frequency of a vibrator. The graph which shows the relationship between the difference of the annealing temperature of a 2nd annealing process and the annealing temperature of a 3rd annealing process, and the amount of frequency fluctuations before and behind a 3rd annealing process. The graph which shows the result of the thermogravimetric analysis of a silicone type conductive adhesive. The table | surface which put together the result of the 1st experiment example, the 2nd experiment example, and the 3rd experiment example. Sectional drawing which shows typically the excitation electrode in each manufacturing process of the conventional vibrator | oscillator.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are essential constituent requirements of the present invention.

1. First, a vibrator that is a target of the vibrator manufacturing method according to the present embodiment will be described with reference to the drawings. FIG. 1A is a cross-sectional view schematically showing a vibrator 100 according to this embodiment. FIG. 1B is a plan view schematically showing the vibrator 100 according to the present embodiment. Note that FIG. 1A is a cross-sectional view taken along line AA in FIG.

  As shown in FIGS. 1A and 1B, the vibrator 100 includes a vibrating piece 102 and a package 110. Hereinafter, the resonator element 102 and the package 110 will be described in detail.

(1) Vibrating Piece FIG. 2 is a perspective view schematically showing the vibrating piece 102. FIG. 3 is a plan view schematically showing the resonator element 102. 4 is a cross-sectional view taken along the line IV-IV in FIG. FIG. 5 is a cross-sectional view taken along the line VV in FIG. 3 schematically showing the resonator element 102.

  As shown in FIGS. 2 to 5, the vibrating piece 102 includes a quartz crystal substrate 10 and excitation electrodes 20 a and 20 b.

  The quartz substrate 10 is made of an AT cut quartz substrate. Here, FIG. 6 is a perspective view schematically showing the AT-cut quartz crystal substrate 101.

Piezoelectric materials such as quartz are generally trigonal and have crystal axes (X, Y, Z) as shown in FIG. The X axis is an electrical axis, the Y axis is a mechanical axis, and the Z axis is an optical axis. The quartz substrate 101 is a so-called rotated Y cut out from a piezoelectric material (for example, artificial quartz crystal) along a plane obtained by rotating an XZ plane (a plane including the X axis and the Z axis) by an angle θ around the X axis. It is a flat plate of a cut quartz substrate. Note that the Y axis and the Z axis are also rotated by θ around the X axis to be the Y ′ axis and the Z ′ axis, respectively. The quartz substrate 101 is a substrate having a plane including the X axis and the Z ′ axis as a main surface and a thickness along the direction along the Y ′ axis. Here, when θ = 35 ° 15 ′, the quartz substrate 101 is an AT-cut quartz substrate. Therefore, the AT-cut quartz substrate 101 is Y ′
The XZ ′ plane (surface including the X axis and Z ′ axis) orthogonal to the axis becomes the main surface (main surface of the vibration part), and thickness shear vibration can be vibrated as the main vibration. The AT-cut quartz substrate 101 can be processed to obtain the quartz substrate 10.

  As shown in FIG. 6, the quartz substrate 10 is a crystal axis of quartz, which is an X axis of an orthogonal coordinate system comprising an X axis as an electric axis, a Y axis as a mechanical axis, and a Z axis as an optical axis. Is the rotation axis, the Z axis is tilted so that the + Z side rotates in the −Y direction, the Z ′ axis, and the Y axis is tilted so that the + Y side rotates in the + Z direction of the Z axis, and the Y ′ axis. And an AT-cut quartz substrate having a plane including the X-axis and the Z′-axis as a main surface and a thickness along the direction along the Y′-axis. 2 to 5 and FIG. 7 described below, an X axis, a Y ′ axis, and a Z ′ axis that are orthogonal to each other are illustrated.

  The quartz substrate 10 is not limited to the AT-cut quartz substrate 101, but may be another piezoelectric substrate such as an SC-cut quartz substrate or a BT-cut quartz substrate that excites thickness shear vibration.

  The quartz substrate 10 has, for example, a Y′-axis direction as a thickness direction, a plan view from the Y′-axis direction (hereinafter, also simply referred to as “plan view”), an X-axis direction as a long side, and a Z′-axis It has a rectangular shape with a short side in the direction. The quartz substrate 10 has a peripheral portion 12 and a vibrating portion 14.

  The peripheral portion 12 is provided around the vibrating portion 14. The peripheral portion 12 is provided along the outer edge of the vibration portion 14. The peripheral portion 12 is thinner than the vibrating portion 14.

  The vibration part 14 is surrounded by the peripheral part 12 in plan view and is thicker than the peripheral part 12. The vibration part 14 has a side along the X axis and a side along the Z ′ axis. Specifically, the vibration unit 14 has a rectangular shape with a long side in the X-axis direction and a short side in the Z′-axis direction in plan view. The vibration unit 14 includes a first portion 15 and a second portion 16.

  The first portion 15 of the vibrating portion 14 is thicker than the second portion 16. In the illustrated example, the first portion 15 is a portion having a thickness t1. The first portion 15 has a quadrangular shape in plan view.

  The second portion 16 of the vibrating portion 14 is smaller in thickness than the first portion 15. In the illustrated example, the second portion 16 is a portion having a thickness t2. The second portion 16 is provided in the + X axis direction and the −X axis direction of the first portion 15. That is, the first portion 15 is sandwiched between the second portions 16 in the X-axis direction. As described above, the vibrating portion 14 includes the two types of portions 15 and 16 having different thicknesses, and the vibrating piece 102 has a two-stage mesa structure.

  The vibration unit 14 can vibrate with thickness shear vibration as the main vibration. Since the vibrating unit 14 has a two-stage mesa structure, the vibrating piece 102 can have an energy confinement effect. “Thickness shear vibration” means that the displacement direction of the quartz substrate is parallel to the main surface of the quartz substrate (in the example shown, the displacement direction of the quartz substrate is the X-axis direction), and the wave propagation direction is the thickness direction of the plate. It is the vibration of the.

  The vibration part 14 includes a first convex part 17 projecting in the + Y′-axis direction from the peripheral part 12, and a second convex part 18 projecting in the −Y′-axis direction from the peripheral part 12. Yes. For example, the convex portions 17 and 18 have the same shape, and the convex portions 17 and 18 have the same size. The convex portions 17 and 18 include the first portion 15 and the second portion 16.

The side surface 17a in the + X-axis direction and the side surface 17b in the −X-axis direction of the first convex portion 17 and the side surface 18a in the + X-axis direction and the side surface 18b in the −X-axis direction of the second convex portion 18 are illustrated in FIG. As shown, two steps are provided depending on the difference between the thickness of the first portion 15 and the thickness of the second portion 16 and the difference between the thickness of the second portion 16 and the thickness of the peripheral portion 12.

  For example, as illustrated in FIG. 4, the side surface 17 c of the first convex portion 17 in the + Z′-axis direction is a surface perpendicular to the surface including the X-axis and the Z′-axis. The side surface 17d in the −Z′-axis direction of the first convex portion 17 is a surface that is inclined with respect to a plane including the X-axis and the Z′-axis, for example.

  For example, as illustrated in FIG. 4, the side surface 18 c of the second convex portion 18 in the + Z′-axis direction is a surface that is inclined with respect to a plane including the X-axis and the Z′-axis. A side surface 18d in the −Z′-axis direction of the second convex portion 18 is a surface perpendicular to the surface including the X-axis and the Z′-axis.

  The side surface 17d of the first convex portion 17 and the side surface 18c of the second convex portion 18 are such that, for example, when an AT-cut quartz substrate is etched using a solution containing hydrofluoric acid as an etching solution, the m-plane of the quartz crystal is exposed. Thus, the surface is inclined with respect to the plane including the X axis and the Z ′ axis. In addition, although not shown in figure, also about the side surface of -Z 'direction other than the side surfaces 17d and 18c of the quartz substrate 10, the m-plane of the quartz crystal is exposed, so that the plane including the X axis and the Z' axis is exposed. The surface may be inclined.

  Further, as shown in FIG. 7, the side surfaces 17d and 18c may be surfaces that are perpendicular to the plane including the X axis and the Z ′ axis. For example, by processing the AT cut quartz substrate by laser or etching the AT cut quartz substrate by dry etching, the side surface 17d and the side surface 18c are perpendicular to the plane including the X axis and the Z ′ axis. It can be a good surface. For convenience, FIG. 2 illustrates the case where the side surfaces 17d and 18c are surfaces perpendicular to the plane including the X axis and the Z ′ axis.

  The 1st excitation electrode 20a and the 2nd excitation electrode 20b are provided so that it may overlap with the vibration part 14 by planar view. In the illustrated example, the excitation electrodes 20 a and 20 b are further provided in the peripheral portion 12. The planar shape (shape seen from the Y′-axis direction) of the excitation electrodes 20a and 20b is, for example, a rectangle. The vibration part 14 is provided inside the outer edges of the excitation electrodes 20a and 20b in plan view. That is, the area of the excitation electrodes 20 a and 20 b is larger than the area of the vibration part 14 in plan view. The excitation electrodes 20 a and 20 b are electrodes for applying a voltage to the vibration unit 14.

  The first excitation electrode 20a is connected to the first electrode pad 24a via the first extraction electrode 22a. The second excitation electrode 20b is connected to the second electrode pad 24b through the second extraction electrode 22b. The electrode pads 24 a and 24 b are provided on the + X axis direction side of the peripheral portion 12.

  FIG. 8 is a cross-sectional view schematically showing the first excitation electrode 20a. As shown in FIG. 8, the first excitation electrode 20a includes a base layer (first layer) 21a and an upper layer (second layer) 21b.

  The foundation layer 21 a is formed on the quartz substrate 10. The underlayer 21a is formed of, for example, a material having adhesion to the quartz substrate 10. The material of the underlayer 21a is, for example, Ti (titanium), V (vanadium), Cr (chromium), Nb (niobium), Ta (tantalum), Hf (hafnium), Mo (molybdenum), Ni (nickel), Zr (Zirconium), Ag (silver), Al (aluminum) and the like. Further, the material of the base layer 21a may be, for example, an alloy whose main component is any one of these metals. When the material of the foundation layer 21a is an alloy containing these metals as main components, the subcomponents include, for example, metals other than the main components, non-metals (for example, Si (silicon), C (carbon), B (boron). ) Etc.). The thickness of the foundation layer 21a is, for example, not less than 3 nm and not more than 300 nm.

  The upper layer 21b is formed on the base layer 21a. The upper layer 21b is made of, for example, a material having high electrical conductivity. Specifically, the material of the upper layer 21b is a noble metal element such as Au (gold) or Pt (platinum). Moreover, the material of the upper layer 21b may be, for example, an alloy containing any one of these metals as a main component. When the material of the upper layer 21b is an alloy containing these metals as a main component, the subcomponent is, for example, a metal other than the main component, a nonmetal (for example, Si (silicon), C (carbon), B (boron)) Etc.). The thickness of the upper layer 21b is, for example, not less than 10 nm and not more than 1000 nm.

  The second excitation electrode 20b, the extraction electrodes 22a and 22b, and the electrode pads 24a and 24b have the same structure as the first excitation electrode 20a described above. That is, the second excitation electrode 20b, the extraction electrodes 22a and 22b, and the electrode pads 24a and 24b have a base layer 21a and an upper layer 21b.

  In the above description, the example in which the area of the excitation electrodes 20a and 20b is larger than the area of the vibration part 14 in plan view has been described. However, the area of the excitation electrodes 20a and 20b in plan view is larger than the area of the vibration part 14. May be small. In this case, the excitation electrodes 20a and 20b are provided inside the outer edge of the vibration unit 14 in plan view.

  In the above description, the two-stage mesa structure in which the vibration unit 14 has two types of portions 15 and 16 having different thicknesses has been described. However, the number of steps of the mesa structure of the resonator element 102 is not particularly limited. For example, the resonator element 102 may have a three-stage mesa structure in which the vibration part has three types of parts having different thicknesses, or a single-stage type mesa in which the vibration part does not have parts having different thicknesses. It may be a structure. The vibrating piece 102 is not limited to a mesa type, and for example, the quartz substrate 10 may have a uniform thickness, a bevel structure, or a convex structure.

  In the above description, the side surfaces 17c and 17d of the first convex portion 17 and the side surfaces 18c and 18d of the second convex portion 18 are provided with a step due to the difference between the thickness of the first portion 15 and the thickness of the second portion 16. Although an example in which the vibration piece 102 is not described has been described, the resonator element 102 may be provided with steps on the side surfaces 17c, 17d, 18c, and 18d.

  Moreover, in the above, it has the 1st convex part 17 which protrudes in the + Y'-axis direction from the peripheral part 12, and the 2nd convex part 18 which protrudes in the -Y'-axis direction rather than the peripheral part 12. However, the resonator element 102 may have only one of the convex portions.

(2) Package As shown in FIGS. 1 (A) and 1 (B), the package 110 covers a box-shaped base (substrate) 112 having a recess 111 opened on the upper surface and an opening of the recess 111. And a plate-like lid 114 joined to the base 112. In FIG. 1B, the lid 114 and the seal ring 113 are not shown for convenience.

  Such a package 110 has a storage space formed by closing the recess 111 with a lid 114, and the vibrating piece 102 is stored and installed in the storage space in an airtight manner. That is, the resonator element 102 is accommodated in the package 110.

  The storage space (recess 111) in which the resonator element 102 is stored may be in a reduced pressure state (vacuum state), or may be filled with an inert gas such as nitrogen, helium, or argon. Good. Thereby, the vibration characteristics of the resonator element 102 are improved.

The material of the base 112 is, for example, various ceramics such as aluminum oxide. The material of the lid 114 is, for example, a material whose linear expansion coefficient approximates that of the base 112. Specifically, when the material of the base 112 is ceramics, the material of the lid 114 is an alloy such as Kovar.

  A first connection terminal 130 and a second connection terminal 132 are provided on the bottom surface of the recess 111 of the package 110. The first connection terminal 130 is provided to face the first electrode pad 24 a of the resonator element 102. The second connection terminal 132 is provided to face the second electrode pad 24 b of the vibrating piece 102. The connection terminals 130 and 132 are electrically connected to the electrode pads 24a and 24b via conductive fixing members (bonding materials) 134, respectively.

  A first external terminal 140 and a second external terminal 142 are provided on the bottom surface of the package 110. The first external terminal 140 is provided at a position overlapping the first connection terminal 130 in a plan view, for example. The second external terminal 142 is provided, for example, at a position overlapping the second connection terminal 132 in plan view. The first external terminal 140 is electrically connected to the first connection terminal 130 through a via (not shown). The second external terminal 142 is electrically connected to the second connection terminal 132 through a via (not shown).

  As the connection terminals 130 and 132 and the external terminals 140 and 142, for example, Ni (nickel), Au (gold), Ag (silver), metallization layer (underlayer) such as Cr (chrome), W (tungsten), etc. A metal film in which respective films such as Cu (copper) are laminated is used. As the conductive fixing member 134, for example, solder, silver paste, a conductive adhesive (an adhesive in which a conductive filler such as metal particles (for example, Ag particles) is dispersed in a resin material) or the like is used. As the conductive adhesive used as the conductive fixing member 134, for example, a silicone-based conductive adhesive can be used.

2. Next, a method for manufacturing a vibrator according to the present embodiment will be described. FIG. 9 is a flowchart illustrating an example of a method for manufacturing a vibrator according to the present embodiment. FIG. 10 is a cross-sectional view schematically showing the manufacturing process of the vibrator according to this embodiment.

  First, as shown in FIG. 10, the vibrating piece 102 is mounted on the base 112 (vibrating piece mounting step S <b> 1).

  Specifically, the vibrating piece 102 is fixed on the connection terminals 130 and 132 provided on the base 112 using a conductive adhesive (bonding material) 134 a.

  Then, the solvent of the conductive adhesive 134a is vaporized by drying the conductive adhesive 134a in a temperature atmosphere of a predetermined temperature (about 180 ° C.).

  Next, the conductive adhesive 134a is heat-treated (first annealing step S2).

  For example, the base 112 on which the resonator element 102 is mounted is introduced into an annealing furnace (not shown), and the conductive adhesive 134a is annealed at a peak heating temperature of about 200 ° C. to 300 ° C. In the first annealing step S2, for example, annealing for 4 hours including heating for 2 hours at the peak heating temperature is performed. In the first annealing step S2, the conductive fixing member 134 can be formed by curing the conductive adhesive 134a.

  Here, in the first annealing step S2, annealing may be performed in a vacuum atmosphere. By performing annealing in a vacuum atmosphere, the degree of oxidation of the excitation electrodes 20a and 20b can be reduced. Thereby, deterioration of an aging characteristic can be suppressed. The same applies to the second annealing step S4 and the third annealing step S6 described later.

  Next, the vibrating piece 102 and the conductive fixing member 134 are cooled to a predetermined temperature, and the annealing furnace is opened and ventilated (ventilation step S3).

  Next, the conductive fixing member 134 and the vibrating piece 102 are heated (second annealing step S4).

  For example, the base 112 on which the vibrating piece 102 is mounted is introduced into an annealing furnace, and the vibrating piece 102 and the conductive fixing member 134 are heated. In the second annealing step S4, the outgas component in the conductive fixing member 134 that could not be sufficiently removed in the first annealing step S2 is removed, and the outgas component adhering to the vibrating piece 102 is removed. It is possible to reduce the stress distortion of the resonator element 102 that could not be completely eliminated in the annealing step S2. The annealing conditions in the second annealing step S4 will be described later.

  Next, the frequency of the resonator element 102 (vibrator 100) is adjusted (frequency adjustment step S5).

  For example, although not shown, the vibrating element 102 is brought into contact with the external terminals 140 and 142 electrically connected to the excitation electrodes 20a and 20b, monitor electrodes (not shown), etc. Excited and measured output frequency. If there is a frequency difference between the measured frequency and a desired frequency, the mass is reduced by irradiating an ion laser or the like to etch part of the excitation electrodes 20a and 20b (ion milling). To adjust the frequency.

  Next, the conductive fixing member 134 and the vibrating piece 102 are heated (third annealing step S6).

  For example, the base 112 on which the vibrating piece 102 is mounted is introduced into an annealing furnace, and the vibrating piece 102 and the conductive fixing member 134 are heated. By the third annealing step S6, the discharge of the outgas component in the conductive fixing member 134 that could not be sufficiently removed by the first annealing step S2 and the second annealing step S4, and the removal of the outgas component attached to the vibrating piece 102, In addition, in the first annealing step S2 and the second annealing step S4, the stress strain of the resonator element 102 that could not be completely eliminated can be reduced. Furthermore, the stress distortion of the resonator element 102 newly added in the frequency adjustment step S5 can be reduced. The annealing conditions in the third annealing step S6 will be described later.

  Next, as shown in FIG. 1A, a lid 114 is joined to the base 112 to seal the recess 111 of the base 112 (sealing step S7). Thereby, the resonator element 102 can be accommodated in the accommodation space (recess 111) of the package 110. The base 112 and the lid 114 are joined by providing the seal ring 113 on the base 112, placing the lid 114 on the seal ring 113, and welding the seal ring 113 to the base 112 using, for example, a resistance welding machine. Is done by. The joining of the base 112 and the lid 114 is not particularly limited, and may be performed using an adhesive or may be performed by seam welding.

  Next, the characteristics of the vibrator 100 are inspected (inspection step S8).

  For example, although not shown, the probe of the measuring device is brought into contact with the external terminals 140 and 142 electrically connected to the excitation electrodes 20a and 20b, the monitor electrode (not shown), etc. Characteristics (DLD (Drive Level Dependence) characteristics, etc.) are measured.

  Through the above steps, the vibrator 100 can be manufactured.

  Next, the annealing conditions of the second annealing step S4 and the third annealing step S6 will be described.

  The annealing temperature in the third annealing step S6 (hereinafter also referred to as “third annealing temperature”) is lower than the annealing temperature in the second annealing step S4 (hereinafter also referred to as “second annealing temperature”). The difference between the second annealing temperature and the third annealing temperature is 15 ° C. or higher, and more desirably 30 ° C. or higher.

  The second annealing temperature is, for example, 320 ° C. or lower. The third annealing temperature is, for example, 200 ° C. or higher, and more desirably 230 ° C. or higher.

  That is, for example, when the difference between the second annealing temperature and the third annealing temperature is 15 ° C. or more and the third annealing temperature is 200 ° C. or more, the second annealing temperature that satisfies the above condition is 215 ° C. or more and 320 ° C. The range is as follows.

  Further, for example, when the difference between the second annealing temperature and the third annealing temperature is 15 ° C. or higher and the third annealing temperature is 230 ° C. or higher, the second annealing temperature satisfying the above condition is 245 ° C. or higher and 320 ° C. The range is as follows. For example, when the difference between the second annealing temperature and the third annealing temperature is 30 ° C. or higher and the third annealing temperature is 200 ° C. or higher, the second annealing temperature satisfying the above condition is 230 ° C. or higher and 320 ° C. The range is as follows. For example, when the difference between the second annealing temperature and the third annealing temperature is 30 ° C. or more and the third annealing temperature is 230 ° C. or more, the second annealing temperature satisfying the above condition is 260 ° C. or more and 320 ° C. The range is as follows.

The annealing time in the second annealing step S4 and the third annealing step S6 is, for example, 1 hour or more and 10 hours or less. The annealing time in the second annealing step S4 and the third annealing step S6 is, for example, 2 hours. The annealing time in the second annealing step S4 and the annealing time in the third annealing step S6 may be the same or different. The degree of vacuum in the second annealing step S4 and the degree of vacuum in the third annealing step S6 are, for example, 10 ⁻⁵ Pa or more and 10 ⁻¹ Pa or less.

  FIG. 11 is a graph showing an example of a temperature change in the annealing furnace in the annealing steps S4 and S6. As shown in FIG. 11, in annealing steps S4 and S6, first, the temperature in the annealing furnace is raised to a temperature higher than the set temperature (annealing temperature), and then the temperature in the annealing furnace is kept constant for a predetermined time. Keep on. Thereafter, the inside of the annealing furnace is cooled to a predetermined temperature (for example, room temperature). Here, the temperature at which the temperature in the annealing furnace is kept constant is referred to as annealing temperature, and the time during which the temperature is maintained at annealing temperature is referred to as annealing time.

  The method for manufacturing the vibrator 100 according to the present embodiment has the following features, for example.

  In the method for manufacturing the vibrator 100 according to the present embodiment, the annealing temperature in the third annealing step S6 is lower than the annealing temperature in the second annealing step S4. Thereby, in 3rd annealing process S6, the spreading | diffusion of the material which comprises the base layer 21a of the excitation electrodes 20a and 20b can be reduced, and the change of the mass by the oxidation of this material, hydroxylation, etc. can be reduced. . Therefore, the variation in the frequency of the vibrator 100 in the third annealing step S6 can be reduced. Hereinafter, this effect will be described in detail.

  FIG. 12 is a cross-sectional view schematically showing the state of the first excitation electrode 20a in each manufacturing process of the vibrator 100 according to the present embodiment. FIG. 12A shows the state of the first excitation electrode 20a in the initial state. FIG. 12B shows the state of the first excitation electrode 20a in the second annealing step S4. FIG. 12C shows the state of the first excitation electrode 20a in the frequency adjustment step S5. FIG. 12D shows the state of the first excitation electrode 20a in the third annealing step S6. In the following, a case will be described in which the first excitation electrode 20a has the base layer 21a made of chromium and the upper layer 21b made of gold.

  As shown in FIG. 12A, the first excitation electrode 20a is formed by laminating the base layer 21a and the upper layer 21b in this order from the quartz substrate 10 side.

  As shown in FIG. 12B, in the second annealing step S4, chromium constituting the underlayer 21a is diffused in the upper layer 21b by heat, and a chromium oxide layer 21c is formed on the surface of the upper layer 21b. Therefore, the mass of the vibrating piece increases by the amount of oxygen.

  As shown in FIG. 12C, in the frequency adjustment step S5, the chromium oxide layer 21c and a part of the upper layer 21b are removed by ion milling that irradiates an ion laser or the like, and the frequency of the vibrator is adjusted. .

  Here, since the annealing temperature in the third annealing step S6 is lower than the annealing temperature in the second annealing step S4, as shown in FIG. 12D, in the third annealing step S6, chromium constituting the underlayer 21a is formed. Diffusion can be reduced, and changes in mass due to chromium oxidation or hydroxylation can be reduced. Therefore, fluctuations in the frequency of the vibrator in the third annealing step S6 can be reduced.

  As described above, in the method for manufacturing the vibrator 100 according to the present embodiment, it is possible to reduce the change in the frequency of the vibrator 100 by reducing the change in mass due to oxidation or water oxidation of the material constituting the base layer 21a. it can. Therefore, the method for manufacturing the vibrator 100 according to the present embodiment is particularly effective for a vibrator having a high frequency of 30 MHz or more, which is highly sensitive to a change in mass.

  In the method for manufacturing the vibrator 100 according to the present embodiment, the difference between the annealing temperature in the second annealing step S4 and the annealing temperature in the third annealing step S6 is 15 ° C. or more. Thereby, the fluctuation | variation of the frequency of the vibrator | oscillator 100 before and after frequency adjustment process S5 can be reduced. Further, the difference between the annealing temperature in the second annealing step S4 and the annealing temperature in the third annealing step S6 may be 30 ° C. or higher. Thereby, the fluctuation | variation of the frequency of the vibrator | oscillator 100 before and behind frequency adjustment process S5 can be reduced more (refer "3.2. 2nd experiment example" mentioned later).

  In the method for manufacturing the vibrator 100 according to the present embodiment, the annealing temperature in the second annealing step S4 is 320 ° C. or lower. Thereby, the state change of the conductive fixing member 134 can be suppressed (see “3.3. Third Experimental Example” described later).

  In the method for manufacturing the vibrator 100 according to the present embodiment, the annealing temperature in the third annealing step S6 is 200 ° C. or higher. Thereby, a vibrator having excellent aging characteristics can be obtained. Furthermore, the annealing temperature in the third annealing step S6 is 230 ° C. or higher. Thereby, a vibrator having better aging characteristics can be obtained (see “3.1. First Experimental Example” described later).

Therefore, according to the method for manufacturing the vibrator 100 according to the present embodiment, it is possible to reduce the frequency variation and manufacture a vibrator having excellent aging characteristics.

3. Experimental Example An experimental example is shown below to describe the present invention more specifically. The present invention is not limited by the following experimental examples.

3.1. First Experimental Example In the method for manufacturing the vibrator 100 described above, an experiment was conducted to examine the relationship between the annealing temperature in the third annealing step S6 and the aging characteristics.

  Specifically, in the method for manufacturing the vibrator 100 described above, the vibrator is respectively used in the third annealing step S6 when the annealing temperature is 170 ° C., 200 ° C., 230 ° C., and 260 ° C. Manufactured and measured for aging characteristics.

  The manufacturing conditions other than the annealing temperature in the third annealing step S6 were the same. Specifically, in the excitation electrodes 20a and 20b, the base layer 21a is made of chromium, and the upper layer 21b is made of gold. The annealing time in the third annealing step S6 was 2 hours. The vibrating piece was sealed in a nitrogen atmosphere. The vibrator was an AT cut type vibrator, and the oscillation frequency was 38.4 MHz.

  The frequency change after 1000 hours at 125 ° C. was measured for each vibrator manufactured in this manner.

  FIG. 13 is a graph showing the relationship between the annealing temperature in the third annealing step S6 and the amount of change in the frequency of the vibrator over time. Each point in the graph shown in FIG. 13 represents an average value of the frequency change amounts of 30 vibrators extracted from 300 vibrators manufactured under the same conditions.

  As shown in FIG. 13, it was found that when the annealing temperature in the third annealing step S6 was 200 ° C. or higher, the frequency change amount was −3.1 ppm or lower, and good aging characteristics were obtained. It was also found that when the annealing temperature in the third annealing step S6 was 230 ° C., the frequency change rate was −2.5 ppm or less, and better aging characteristics were obtained.

3.2. Second Experimental Example In the method of manufacturing the vibrator 100 described above, the difference between the annealing temperature in the second annealing step S4 and the annealing temperature in the third annealing step S6, the amount of frequency fluctuation before and after the third annealing step S6, An experiment was conducted to investigate the relationship.

  Specifically, when the annealing temperature in the second annealing step S4 is 290 ° C. and the annealing temperature in the third annealing step S6 is 260 ° C. (temperature difference −30 ° C.), it is 275 ° C. (temperature difference −15 ° C.). In this case, for each case where the temperature was 290 ° C. (temperature difference 0 ° C.), the respective vibrators were produced, and the amount of frequency fluctuation before and after the third annealing step S6 was measured.

  The manufacturing conditions other than the annealing temperature in the third annealing step S6 were the same. Specifically, in the excitation electrodes 20a and 20b, the base layer 21a is made of chromium, and the upper layer 21b is made of gold. The annealing time in the second annealing step S4 and the annealing time in the third annealing step S6 were each 2 hours. The vibrator was an AT cut type vibrator and the oscillation frequency was 48 MHz.

Similarly, when the annealing temperature in the second annealing step S4 is 275 ° C. and the annealing temperature in the third annealing step S6 is 260 ° C. (temperature difference −15 ° C.), it is 275 ° C. (temperature difference 0 ° C.). In the case where the temperature was set to 290 ° C. (temperature difference + 15 ° C.), the respective vibrators were produced, and the frequency fluctuation amount before and after the third annealing step S6 was measured.

  Similarly, when the annealing temperature in the second annealing step S4 is 260 ° C. and the annealing temperature in the third annealing step S6 is 260 ° C. (temperature difference 0 ° C.), the case is 275 ° C. (temperature difference + 15 ° C.). In the case of 290 ° C. (temperature difference + 30 ° C.), each vibrator was manufactured, and the amount of frequency fluctuation before and after the third annealing step S6 was measured.

  FIG. 14 is a graph showing the relationship between the difference between the annealing temperature in the second annealing step S4 and the annealing temperature in the third annealing step S6 and the amount of frequency fluctuation before and after the third annealing step S6. In addition, each point of the graph shown in FIG. 14 represents the average value of the frequency change amount of 100 vibrators manufactured under the same conditions. Further, the results shown in the graph of FIG. 14 show that the influence of the sealing stress and the surface moisture desorption in the third annealing step S6 are excluded, and only the influence of the mass change due to the diffusion and oxidation of chromium. It is taken out.

  As shown in FIG. 14, the annealing temperature in the third annealing step S6 is lower than the annealing temperature in the second annealing step S4, and the difference between the annealing temperature in the second annealing step S4 and the annealing temperature in the third annealing step S6. When the temperature was 15 ° C. or higher, the frequency fluctuation rate before and after the third annealing step S6 was −10 ppm or less, and it was found that the influence of diffusion and oxidation of chromium was reduced.

  Furthermore, the annealing temperature in the third annealing step S6 is lower than the annealing temperature in the second annealing step S4, and the difference between the annealing temperature in the second annealing step S4 and the annealing temperature in the third annealing step S6 is 30 ° C. or more. In some cases, the frequency variation rate before and after the third annealing step S6 was −3 ppm or less, and it was found that the influence of chromium diffusion and oxidation was further reduced.

  In addition, although the result of the experiment when the annealing temperature in the second annealing step S4 is 290 ° C., 275 ° C., and 260 ° C. is shown here, the temperature of the second annealing step S4 is as shown in FIG. Regardless, the same trend is expected.

3.3. Third Experimental Example A thermal analysis of the conductive adhesive 134a used in the method for manufacturing the vibrator 100 described above was performed. Specifically, a thermogravimetric analysis (TGA) of the silicone-based conductive adhesive was performed by using a silicone-based conductive adhesive as the conductive adhesive 134a. As the silicone-based conductive adhesive, one using silicone as a binder and silver as a conductive filler was used.

  FIG. 15 is a graph showing the results of thermogravimetric analysis of a silicone-based conductive adhesive. As shown in FIG. 15, when it exceeded 320 degreeC, the weight change was seen and it turned out that a silicone type conductive adhesive raises a state change. That is, it was found that the state change of the conductive adhesive can be suppressed by setting the annealing temperature in the second annealing step S4 to 320 ° C. or lower.

3.4. Summary FIG. 16 is a table summarizing the results of the first experimental example, the second experimental example, and the third experimental example. Specifically, the table shown in FIG. 16 shows the conditions obtained in the first experimental example (the annealing temperature in the third annealing step S6 is set to 200 ° C. or higher) and the conditions obtained in the second experimental example (first 2) The difference between the annealing temperature in the second annealing step S4 and the annealing temperature in the third annealing step S6 is 15 ° C. or higher, and the conditions obtained in the third experimental example (the annealing temperature in the second annealing step S4 is 320 ° C. or lower). This is a summary of the results of the determination as to whether or not the condition is satisfied.

  From the table shown in FIG. 16, the annealing temperature in the second annealing step S4 that satisfies all the above conditions is 215 ° C. or higher and 320 ° C. or lower, and the annealing temperature in the third annealing step S6 is higher than the annealing temperature in the second annealing step S4. Was also 15 ° C. lower and 200 ° C. or higher.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 2 ... Base layer, 4 ... Upper layer, 6 ... Chromium oxide layer, 10 ... Quartz substrate, 12 ... Peripheral part, 14 ... Vibrating part, 15 ... 1st part, 16 ... 2nd part, 17 ... 1st convex part, 17a , 17b, 17c, 17d ... side face, 18 ... second convex part, 18a, 18b, 18c, 18d ... side face, 20a ... first excitation electrode, 20b ... second excitation electrode, 21a ... base layer, 21b ... upper layer, 21c Chrome oxide layer, 22a ... first extraction electrode, 22b ... second extraction electrode, 24a ... first electrode pad, 24b ... second electrode pad, 100 ... vibrator, 101 ... AT-cut quartz crystal substrate, 102 ... vibration piece, DESCRIPTION OF SYMBOLS 110 ... Package, 111 ... Recessed part, 112 ... Base, 113 ... Seal ring, 114 ... Lid, 130 ... First connection terminal, 132 ... Second connection terminal, 134 ... Conductive fixing member, 134a ... Conductive adhesive, 140 ... outside the first Terminal, 142 ... second external terminal

Claims (8)

Mounting the resonator element on the substrate using a bonding material;
Heat-treating the bonding material and the resonator element at a first temperature;
Adjusting the frequency of the resonator element after the heat treatment at the first temperature;
After the step of adjusting the frequency, the step of heat-treating the bonding material and the resonator element at a second temperature;
Including
The second temperature is lower than the first temperature;
The vibrator manufacturing method, wherein a difference between the first temperature and the second temperature is 15 ° C. or more. In claim 1,
The first temperature is 215 ° C. or more and 320 ° C. or less,
The method for manufacturing a vibrator, wherein the second temperature is 200 ° C. or higher. In claim 1 or 2,
The method for manufacturing a vibrator, wherein a difference between the first temperature and the second temperature is 30 ° C. or more. In any one of Claims 1 thru | or 3,
The method for manufacturing a vibrator, wherein the second temperature is 230 ° C. or higher. In any one of Claims 1 thru | or 4,
A method for manufacturing a vibrator including a step of heat-treating the bonding material and curing the bonding material before the step of heat-treating at the first temperature. In any one of Claims 1 thru | or 5,
The vibrating piece includes a quartz substrate and an excitation electrode,
The excitation electrode has a first layer formed on the quartz substrate, and a second layer formed on the first layer;
The method for manufacturing a vibrator, wherein the first layer is titanium, vanadium, chromium, niobium, tantalum, hafnium, molybdenum, nickel, zirconium, silver, aluminum, or an alloy containing these as a main component. In claim 6,
The method for manufacturing a vibrator, wherein the second layer is gold, platinum, or an alloy containing these as a main component. In any one of Claims 1 thru | or 7,
The method for manufacturing a vibrator, wherein the bonding material is a silicone-based conductive adhesive.

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