JP2017076910A - Method of manufacturing piezoelectric vibration piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a piezoelectric vibration piece capable of preventing reduction in manufacturing efficiency.SOLUTION: Provided is a method of manufacturing a piezoelectric vibration piece 3 that comprises: a piezoelectric plate 30 having a pair of vibration arm parts 31; an excitation electrode formed on the pair of vibration arm parts 31 and that vibrates the vibration arm parts 31 by being applied with a voltage; and a weight metal film 50 for frequency adjustment formed on the pair of vibration arm parts 31. The method includes a trimming step of removing the weight metal film 50 through an opening 73a by using a first mask 71 that has the opening 73a at a part corresponding to a formation region of the weight metal film 50, of the piezoelectric plate 30. The first mask 71 has: a first sub mask 72 formed of an insulation material, and arranged on the piezoelectric plate 30; and a first main mask 73 arranged on the first sub mask 72, at an opposite side to the piezoelectric plate 30.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a method for manufacturing a piezoelectric vibrating piece.

  For example, a piezoelectric vibrator using a crystal or the like is used in an electronic device such as a mobile phone or a personal digital assistant device as a device used for a timing source such as a time source or a control signal, a reference signal source, or the like. As this type of piezoelectric vibrator, a piezoelectric vibrator in which a piezoelectric vibrating piece is hermetically sealed in a package in which a cavity is formed is known.

  The piezoelectric vibrating piece described above includes a base portion and a pair of vibrating arm portions extending in parallel with each other from the base portion. The piezoelectric vibrating piece vibrates at a predetermined resonance frequency in a direction in which each vibrating arm portion approaches and separates from each other starting from a base end portion (a connecting portion with the base portion).

  Here, as a method of adjusting the frequency of the piezoelectric vibrating piece (vibrating arm portion), a weight metal film is formed in advance on the tip of the vibrating arm portion, and the weight metal film is partially removed (trimmed) to obtain the vibrating arm portion. There is a method for adjusting the frequency of the vibrating arm so that the frequency of the vibrating arm portion becomes a target value. For example, in Patent Document 1 below, a weight metal film is irradiated with a laser beam, the weight metal film is partially removed and the resonance frequency is roughly adjusted, and then the weight metal film is irradiated with an ion beam. Thus, a configuration for finely adjusting the resonance frequency is disclosed.

  The ion beam is applied to the weight metal film through a mask in order to prevent the ion beam from being applied to a portion other than the weight metal film. This mask is formed of a metal material in consideration of processing accuracy and heat resistance.

JP 2013-118652 A

  By the way, when measuring the frequency of the piezoelectric vibrating piece, a voltage is applied between a pair of excitation electrodes formed on the surface of the vibrating arm portion to vibrate the piezoelectric vibrating piece. In order to adjust the frequency with higher accuracy, it is desirable to measure the frequency during or before trimming. However, since the mask used for trimming is made of a metal material, when the frequency is measured with the mask placed, the mask contacts the excitation electrode and the excitation electrode is short-circuited by the mask, and the frequency is accurately measured. You may not be able to. For this reason, in the conventional method of manufacturing a piezoelectric vibrating piece, it is necessary to measure the frequency in a state where the mask is retracted from the piezoelectric vibrating piece, and there is a problem that manufacturing efficiency is lowered.

  Therefore, the present invention provides a method for manufacturing a piezoelectric vibrating piece capable of adjusting the frequency with high accuracy while improving the manufacturing efficiency.

  A method of manufacturing a piezoelectric vibrating piece according to the present invention includes a piezoelectric plate having a pair of vibrating arms, an excitation electrode formed on the pair of vibrating arms and vibrating the vibrating arms by applying a voltage, and A method of manufacturing a piezoelectric vibrating piece including a frequency-adjusting weight metal film formed on the pair of vibrating arms, wherein an opening is formed in a portion of the piezoelectric plate corresponding to the weight metal film formation region. A trimming step of removing the weight metal film through the opening, and the first mask is formed of an insulating material and is disposed on the piezoelectric plate; and the submask And a main mask disposed on the opposite side of the piezoelectric plate.

  According to the present invention, the main mask can be disposed on the piezoelectric plate through the submask formed of an insulating material in the trimming process. For this reason, when the main mask is formed of a metal material, the main mask can be prevented from coming into contact with the excitation electrode formed on the vibrating arm portion of the piezoelectric plate and the excitation electrode being short-circuited. Accordingly, even when the first mask is disposed on the piezoelectric plate in order to remove the weight metal film, it is possible to apply a voltage to the excitation electrode to vibrate the vibrating arm portion, Can be measured. Accordingly, when the frequency of the piezoelectric vibrating piece is measured, it is not necessary to retract the first mask from the piezoelectric plate, the manufacturing efficiency can be improved, the frequency can be adjusted with high accuracy, and the vibration characteristics are excellent. A piezoelectric vibrating piece can be manufactured.

In the method for manufacturing the piezoelectric vibrating piece, in the trimming step, ion milling is performed on the weight metal film in a state where the second mask is disposed on the side opposite to the first mask side with the piezoelectric plate interposed therebetween. Preferably, the second mask has an avoiding portion that exposes an electrode film connected to the excitation electrode.
According to the present invention, since the second mask is disposed on the opposite side of the first mask with the piezoelectric plate interposed therebetween, the particles of the weight metal film bounced off by ion milling have the first mask sandwiched between the piezoelectric plate. It is possible to prevent re-adhering to the piezoelectric plate around the opposite side.
Furthermore, since the second mask is provided with an avoiding portion that exposes the electrode film connected to the excitation electrode, the probe of the measuring instrument is placed in a state where the first mask and the second mask are arranged on the piezoelectric plate. Etc. can be brought into contact with the excitation electrode by contacting the electrode film. This eliminates the need for the first mask and the second mask to be retracted from the piezoelectric plate when measuring the frequency of the piezoelectric vibrating piece, thereby preventing a reduction in manufacturing efficiency.
Further, by providing the avoidance portion in the second mask, the reattachment of the metal film particles to the piezoelectric plate through the avoidance portion can be suppressed as compared with the case where the avoidance portion is provided in the first mask. Layout can be improved.

In the above-described method for manufacturing a piezoelectric vibrating piece, it is preferable that the trimming step includes a measuring step of measuring the vibration frequency of the pair of vibrating arm portions.
According to the present invention, the frequency of the piezoelectric vibrating piece after the trimming process can be measured while the first mask is disposed in the measuring process. For this reason, according to the measurement result in the measurement process, the frequency of the piezoelectric vibrating piece can be adjusted with higher accuracy while improving the manufacturing efficiency, for example, by performing the trimming process again with the first mask disposed. it can.

In the above-described method for manufacturing a piezoelectric vibrating piece, it is preferable that the trimming step is performed while measuring the frequency of the pair of vibrating arms.
According to the present invention, since the weight metal film can be removed while measuring the frequency of the piezoelectric vibrating piece, the frequency of the piezoelectric vibrating piece can be adjusted with higher accuracy.

  According to the present invention, the main mask can be disposed on the piezoelectric plate through the submask formed of an insulating material in the trimming process. For this reason, when the main mask is formed of a metal material, the main mask can be prevented from coming into contact with the excitation electrode formed on the vibrating arm portion of the piezoelectric plate and the excitation electrode being short-circuited. Accordingly, even when the first mask is disposed on the piezoelectric plate in order to remove the weight metal film, it is possible to apply a voltage to the excitation electrode to vibrate the vibrating arm portion, Can be measured. Accordingly, when the frequency of the piezoelectric vibrating piece is measured, it is not necessary to retract the first mask from the piezoelectric plate, the manufacturing efficiency can be improved, the frequency can be adjusted with high accuracy, and the vibration characteristics are excellent. A piezoelectric vibrating piece can be manufactured.

1 is an external perspective view of a piezoelectric vibrator according to an embodiment of the present invention. It is a top view of the piezoelectric vibrator which shows the state which removed the sealing board. It is sectional drawing in the part corresponded to the III-III line of FIG. 1 is an exploded perspective view of a piezoelectric vibrator according to an embodiment. It is a top view of a piezoelectric vibrating piece. It is a bottom view of a piezoelectric vibrating piece. It is sectional drawing which follows the VII-VII line of FIG. It is process drawing for demonstrating a frequency rough adjustment process, Comprising: It is a fragmentary top view of the wafer in which the piezoelectric vibrating piece was formed. It is process drawing for demonstrating a frequency rough adjustment process, Comprising: It is a partial bottom view of the wafer in which the piezoelectric vibrating piece was formed. It is process drawing for demonstrating a frequency rough adjustment process, Comprising: It is sectional drawing in the part corresponded to the XX line of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Piezoelectric vibrator)
FIG. 1 is an external perspective view of a piezoelectric vibrator according to an embodiment of the present invention. FIG. 2 is a plan view of the piezoelectric vibrator showing a state where the sealing plate is removed. FIG. 3 is a cross-sectional view taken along a line III-III in FIG. FIG. 4 is an exploded perspective view of the piezoelectric vibrator according to the embodiment.
As shown in FIGS. 1 to 4, the piezoelectric vibrator 1 is a so-called ceramic package type surface mount vibrator, and is housed in the cavity C and the package 2 having the cavity C hermetically sealed therein. The piezoelectric vibrating piece 3 is provided. The piezoelectric vibrator 1 has a rectangular parallelepiped shape. Therefore, in the present embodiment, the longitudinal direction of the piezoelectric vibrator 1 in the plan view is referred to as the longitudinal direction L, the short direction is referred to as the width direction W, and the direction perpendicular to the longitudinal direction L and the width direction W is the thickness. It is called direction T.

The package 2 includes a package body 5 and a sealing plate 6 that is bonded to the package body 5 and that forms a cavity C between the package body 5 and the package body 5.
The package main body 5 includes a first base substrate 10 and a second base substrate 11 which are joined in a state of being overlapped with each other, and a seal ring 12 which is joined on the second base substrate 11.

  The first base substrate 10 is a ceramic substrate having a rectangular shape in plan view as viewed from the thickness direction T. A pair of external electrodes 21 </ b> A and 21 </ b> B are formed on the lower surface of the first base substrate 10 at intervals in the longitudinal direction L. The external electrodes 21A and 21B are configured by a single-layer film made of a single metal formed by, for example, vapor deposition or sputtering, or a stacked film in which different metals are stacked.

The second base substrate 11 is a ceramic substrate having the same shape as that of the first base substrate 10 in plan view, and is integrally joined by sintering or the like while being superimposed on the first base substrate 10. ing.
In addition, as a ceramic material used for each base substrate 10 and 11, for example, HTCC (High Temperature Co-Fired Ceramic) made of alumina, LTCC (Low Temperature Co-Fired Ceramic) made of glass ceramics, or the like can be used. It is. The upper surface of the second base substrate 11 is a mounting surface on which the piezoelectric vibrating reed 3 is mounted.

  As shown in FIGS. 2 to 4, the second base substrate 11 is formed with a through portion 11 a that penetrates the second base substrate 11 in the thickness direction T. The penetration part 11a has a rectangular shape in plan view, and its four corners are rounded.

  On the upper surface of the second base substrate 11, a pair of electrode pads 20 </ b> A and 20 </ b> B that are connection electrodes with the piezoelectric vibrating piece 3 are formed. Similarly to the external electrodes 21A and 21B described above, the electrode pads 20A and 20B are configured by a single-layer film made of a single metal formed by, for example, vapor deposition or sputtering, or a stacked film in which different metals are stacked. The electrode pads 20A and 20B and the external electrodes 21A and 21B are electrically connected to each other through through wirings 22A and 22B that penetrate the base substrates 10 and 11 in the thickness direction T, respectively.

  At the four corners of each base substrate 10, 11, cut-out portions 15 having a ¼ arc shape in plan view are formed over the entire thickness direction T of both base substrates 10, 11. Each of the base substrates 10 and 11 is formed, for example, by stacking and joining two wafer-shaped ceramic substrates, and then forming a plurality of through holes penetrating both ceramic substrates in a matrix, and using both ceramic substrates as a reference. It is produced by cutting into a lattice shape. At that time, the through-hole is divided into four, so that the above-described notch portion 15 is configured.

  The seal ring 12 is a conductive frame member that is slightly smaller than the outer shape of each of the base substrates 10 and 11, and is bonded to the upper surface of the second base substrate 11. Specifically, the seal ring 12 is bonded to the second base substrate 11 by baking with a brazing material such as silver brazing or a solder material, or by welding to a metal bonding layer formed on the second base substrate 11. Has been. The seal ring 12 constitutes the side wall of the cavity C together with the inner side surface of the penetrating portion 11 a of the second base substrate 11.

Examples of the material of the seal ring 12 include a nickel-based alloy, and specifically, it may be selected from Kovar, Elinvar, Invar, 42-alloy, and the like. In particular, as the material of the seal ring 12, it is preferable to select a material having a thermal expansion coefficient close to that of the base substrates 10 and 11 made of ceramics. For example, when alumina having a thermal expansion coefficient of 6.8 × 10 ⁻⁶ / ° C. is used as the base substrates 10 and 11, Kovar having a thermal expansion coefficient of 5.2 × 10 ⁻⁶ / ° C. or thermal expansion is used as the seal ring 12. It is preferable to use 42-alloy having a coefficient of 4.5 to 6.5 × 10 ⁻⁶ / ° C.

  The sealing plate 6 is made of a conductive substrate, and is joined onto the seal ring 12 to hermetically seal the inside of the package body 5. The space defined by the seal ring 12, the sealing plate 6, and the base substrates 10 and 11 constitutes a hermetically sealed cavity C.

(Piezoelectric vibrating piece)
FIG. 5 is a plan view of the piezoelectric vibrating piece. FIG. 6 is a bottom view of the piezoelectric vibrating piece.
As shown in FIGS. 5 and 6, the piezoelectric vibrating piece 3 includes a piezoelectric plate 30, excitation electrodes 41 and 42 formed on the piezoelectric plate 30, mount electrodes 43 and 44, extraction electrodes 45 and 46, and a weight metal film. 50. The longitudinal direction L, the width direction W, and the thickness direction T of the piezoelectric vibrator 1 coincide with the longitudinal direction, the width direction, and the thickness direction of the piezoelectric vibrating piece 3, respectively.

The piezoelectric plate 30 is made of a piezoelectric material such as quartz, lithium tantalate, or lithium niobate. The piezoelectric plate 30 has a pair of vibrating arm portions 31 and 32 arranged in parallel, and a base portion 33 that integrally fixes the base end portions of the pair of vibrating arm portions 31 and 32.
The vibrating arm portions 31 and 32 extend from the base portion 33 along the longitudinal direction L and are arranged side by side in the width direction W. On both main surfaces of the pair of vibrating arm portions 31 and 32, groove portions 37 that are recessed in the thickness direction T and that extend along the longitudinal direction L are formed. These groove portions 37 are formed in the longitudinal direction L from the base end portions of the vibrating arm portions 31 and 32 to the vicinity of the middle.

The excitation electrodes 41 and 42 are electrodes that vibrate the pair of vibrating arm portions 31 and 32 at a predetermined frequency in a direction approaching and separating from each other when a voltage is applied. Each excitation electrode 41 and 42 is formed by patterning on the outer surface of the pair of vibrating arm portions 31 and 32 while being electrically separated from each other.
Specifically, the first excitation electrode 41 is mainly formed on the groove portion 37 of one vibrating arm portion 31 and on both side surfaces of the other vibrating arm portion 32. Further, second excitation electrodes 42 are mainly formed on both side surfaces of one vibrating arm portion 31 and on a groove portion 37 of the other vibrating arm portion 32.

  Further, the first excitation electrode 41 and the second excitation electrode 42 are mounted on both main surfaces of the base portion 33 via lead electrodes 45 and 46, respectively, on the main surfaces of the base portion 33. Is electrically connected. The piezoelectric vibrating reed 3 is applied with a voltage via the mount electrodes 43 and 44.

  As shown in FIG. 5, a weight metal film 50 for adjusting the frequency of the vibrating arm portions 31, 32 is formed on the distal ends of the pair of vibrating arm portions 31, 32. The weight metal film 50 is formed on the first main surface of the piezoelectric plate 30. The weight metal film 50 increases the mass at the distal end portion of each vibrating arm portion 31, 32, and suppresses an increase in frequency due to the shortening of the length of each vibrating arm portion 31, 32. The weight metal film 50 is made of, for example, Au or Ag, and has a thickness of about 1 to 10 μm.

7 is a cross-sectional view taken along line VII-VII in FIG.
Here, a concave portion 51 that is recessed in the thickness direction T is formed at the tip of each weight metal film 50. The concave portion 51 is formed by partially removing (trimming) the weight metal film 50 by ion milling in a frequency coarse adjustment step described later. The concave portion 51 of the present embodiment opens the weight metal film 50 toward both sides in the width direction W and the tip side in the longitudinal direction L, but does not penetrate in the thickness direction T. In the example shown in FIG. 7, in the longitudinal sectional view along the longitudinal direction L, the recess 51 has a linear shape with the distal end extending along the longitudinal direction L, and the base end is the base of the vibrating arm portions 31 and 32. It has a curved shape whose depth becomes shallower toward the end side.

  As shown in FIGS. 2 to 4, the piezoelectric vibrating reed 3 described above is accommodated in a cavity C of a hermetically sealed package 2. Specifically, the piezoelectric vibrating reed 3 includes a conductive adhesive on the electrode pads 20A and 20B in which the mount electrodes 43 and 44 (see FIGS. 5 and 6) are formed in the package 2 in the cavity C, respectively. Has been implemented through. Thereby, in the cavity C, the piezoelectric vibrating reed 3 is supported in a state of floating from the base substrates 10 and 11, and the mount electrodes 43 and 44 and the electrode pads 20A and 20B are connected via the conductive adhesive. Is done. In addition, it is also possible to use a metal bump instead of the conductive adhesive as the conductive bonding material described above. The common point between the conductive adhesive and the metal bump is that the conductive bonding material has fluidity in the initial stage of bonding and solidifies in the latter stage of bonding to exhibit bonding strength.

  In order to operate the piezoelectric vibrator 1 configured as described above, a predetermined voltage is applied to the external electrodes 21A and 21B. Then, a current flows through the excitation electrodes 41 and 42 shown in FIGS. 5 and 6, and an electric field is generated between the excitation electrodes 41 and 42. The vibrating arm portions 31 and 32 vibrate at a predetermined resonance frequency, for example, in a direction (width direction W) approaching or separating from each other by an inverse piezoelectric effect caused by an electric field generated between the excitation electrodes 41 and 42. The vibrations of the vibrating arm portions 31 and 32 are used as a time source, a control signal timing source, a reference signal source, and the like.

(Piezoelectric vibrator manufacturing method)
Next, a method for manufacturing the piezoelectric vibrator 1 of this embodiment will be described. In addition, refer to FIGS. 1 to 7 for the reference numerals of the respective components in the following description.
First, the piezoelectric vibrating piece 3 is created. Specifically, an external pattern (not shown) of the piezoelectric vibrating piece 3 (piezoelectric plate 30) is formed on both surfaces of the wafer 60 (see FIG. 8) by photolithography. At this time, a plurality of outer shape patterns are formed on the wafer 60 (outer shape forming step). Next, both surfaces of the wafer 60 are etched using the external pattern as a mask. Thereby, the region not masked by the outer pattern is selectively removed, and the outer shape of the piezoelectric plate 30 is formed. In this state, each piezoelectric plate 30 is connected to the wafer 60 via the connecting portion 61 (see FIG. 8).

Next, the respective vibrating arm portions 31 and 32 are etched to form groove portions 37 on both main surfaces of the respective vibrating arm portions 31 and 32 (groove portion forming step).
Subsequently, the electrode films are patterned on the outer surfaces of the plurality of piezoelectric vibrating reeds 3 to form excitation electrodes 41 and 42, mount electrodes 43 and 44, and extraction electrodes 45 and 46, respectively (electrode formation step). Specifically, an electrode film is formed on the outer surface of the plurality of piezoelectric vibrating reeds 3 by vapor deposition, sputtering, or the like, and then the electrode film is etched.
Then, a weight metal film 50 for adjusting the frequency is formed on the surface of the tip of the vibrating arms 31 and 32 (weight metal film forming step). In addition, you may perform an electrode formation process and a weight metal film formation process collectively.

8 to 10 are process diagrams for explaining the frequency coarse adjustment process. FIG. 8 is a partial plan view of the wafer on which the piezoelectric vibrating piece is formed, and FIG. 9 is a view on which the piezoelectric vibrating piece is formed. FIG. 10 is a partial bottom view of the wafer, and FIG. 10 is a cross-sectional view of a portion corresponding to line XX in FIG.
Next, as shown in FIGS. 8 to 10, a frequency coarse adjustment process is performed to coarsely adjust the resonance frequency for each piezoelectric vibrating piece 3 formed on the wafer 60. In the coarse frequency adjustment process of the present embodiment, the weight metal film 50 is partially removed (trimmed) by ion milling. The rough frequency adjustment step includes a mask placement step and a trimming step.

  In the mask arrangement step, the first mask 71 is arranged on the first main surface of the wafer 60, and the second mask 76 is arranged on the second main surface opposite to the first main surface of the wafer 60. The first mask 71 includes a first submask 72 (submask) and a first main mask 73 (main mask). The second mask 76 includes a second submask 77 and a second main mask 78. The mask placement process includes a submask placement process for placing the submasks 72 and 77 and a main mask placement process for placing the main masks 73 and 78.

In the submask placement step, the submasks 72 and 77 are placed on the piezoelectric plate 30 by patterning a photoresist film (not shown) by photolithography. Each photoresist film is formed of a resin material such as photosensitive polyimide. Each of the submasks 72 and 77 is disposed in a region that avoids at least the surfaces of the vibrating arm portions 31 and 32. In the present embodiment, the submasks 72 and 77 are arranged by being patterned so as to cover the surface of the base portion 33. In the thickness direction T, the outer surface of the first submask 72 is formed so as to be located outside the outer end surface of the weight metal film 50. In the second submask 77, an opening 77a (avoidance portion) for exposing the mount electrodes 43 and 44 (electrode film) is formed.
Each of the submasks 72 and 77 may be disposed only on each main surface of the base portion 33, or may be disposed on the entire surface including the side surface of the base portion 33 as a single unit. Good. Further, each of the submasks 72 and 77 may be arranged from the base portion 33 to the connecting portion 61.

  In the main mask arrangement process, the main masks 73 and 78 formed of, for example, SUS or titanium are arranged on the piezoelectric plate 30. Specifically, in the main mask placement step, first, the wafer 60 on which the submasks 72 and 77 are placed is set on a jig in a chamber (not shown). Subsequently, the first main mask 73 is disposed on the opposite side of the piezoelectric plate 30 with respect to the first submask 72 on the wafer 60. At this time, the first main mask 73 may be disposed so as to overlap the first submask 72 or may be disposed with a gap with respect to the first submask 72. The first main mask 73 covers the wafer 60 from the first main surface side. In the first main mask 73, an opening 73a is formed in a portion of the weight metal film 50 corresponding to a region to be trimmed (hereinafter referred to as trimming region R). The opening 73 a collectively exposes portions corresponding to the trimming region R of the weight metal film 50 among the piezoelectric vibrating reeds 3 arranged in the width direction W on the wafer 60. In the present embodiment, the base end portion of the weight metal film 50 is covered with the first main mask 73 and the tip end portion is exposed as a trimming region R through the opening 73a.

  The second main mask 78 is disposed on the opposite side of the piezoelectric plate 30 with respect to the second submask 77 on the wafer 60. At this time, the second main mask 78 may be disposed so as to overlap the second submask 77, or may be disposed with a gap with respect to the second submask 77. The second main mask 78 covers the wafer 60 from the second main surface side. An opening 78 a (avoidance portion) is formed in the second main mask 78 at a position corresponding to the opening 77 a of the second submask 77. Therefore, the second mask 76 (the second submask 77 and the second main mask 78) exposes the mount electrodes 43 and 44 through the openings 77a and 78a.

  Subsequently, ion milling is performed on the wafer 60 set in the chamber (trimming process). Specifically, the pressure in the chamber is reduced and a process gas such as argon is introduced into the chamber. When an acceleration voltage is applied in this state, the ionized process gas collides with the trimming region R of the weight metal film 50 through the opening 73a of the first main mask 73. As a result, the weight metal film 50 in the trimming region R is blown off from the surface layer portion, and the above-described recess 51 is formed in the weight metal film 50. Then, the weight metal film 50 is trimmed, and the mass of the vibrating arm portions 31 and 32 changes, whereby the frequency of the vibrating arm portions 31 and 32 (the frequency of the piezoelectric vibrating piece 3) changes. The trimming amount in the trimming step is determined according to the difference between the measured frequency and a predetermined target frequency by measuring the frequencies of all the piezoelectric vibrating reeds 3 formed on the wafer 60 in advance. In this case, the trimming amount is set to a depth at which the weight metal film 50 does not penetrate in the thickness direction T. Further, the particles of the weight metal film 50 blown off from the trimming region R are detached from the wafer 60 mainly through the opening 73 a of the first main mask 73.

  Subsequently, the frequency of vibration of the vibrating arm portions 31 and 32 is measured again using a measuring instrument that measures the frequency of vibration of the vibrating arm portions 31 and 32 (measurement step). Specifically, a pair of probes of the measuring instrument is inserted into the openings 77 a and 78 a of the second mask 76 and pressed against the mount electrodes 43 and 44. Accordingly, the probe of the measuring instrument and the mount electrodes 43 and 44 can be electrically connected in a state where the first mask 71 and the second mask 76 are arranged on the wafer 60. In this state, a voltage is applied to the excitation electrodes 41 and 42 via the mount electrodes 43 and 44 to vibrate the vibrating arm portions 31 and 32, and the vibration frequency is measured.

  After the measurement process, a singulation process is performed in which the connecting portion 61 of the wafer 60 is cut to separate the piezoelectric vibrating reeds 3 from the wafer 60. Thereby, a plurality of piezoelectric vibrating reeds 3 can be manufactured at one time from one wafer 60.

  Next, after applying a conductive adhesive on the electrode pads 20A and 20B of the package body 5, the base 33 of the piezoelectric vibrating piece 3 is placed on each conductive adhesive. Thereafter, the package body 5 on which the piezoelectric vibrating piece 3 is placed is baked, and the conductive adhesive is dried. Thereby, the piezoelectric vibrating piece 3 is mounted on the package body 5.

  Subsequently, a frequency fine adjustment process for finely adjusting the resonance frequency is performed on the piezoelectric vibrating reed 3 mounted on the package body 5. In the frequency fine adjustment process of the present embodiment, the weight metal film 50 is trimmed by ion milling or laser beam irradiation. At this time, in the fine frequency adjustment step, for example, the trimming amount of the weight metal film 50 per unit time is set smaller than in the rough frequency adjustment step. Thereby, the frequency of the piezoelectric vibrating piece 3 can be finely adjusted so as to be within a predetermined range of the nominal frequency. The trimming amount in the frequency fine adjustment process is determined according to the difference between the frequency measured in the measurement process and a predetermined target frequency. In this case, the trimming amount is set to a depth at which the weight metal film 50 does not penetrate in the thickness direction T.

Thereafter, the sealing plate 6 is joined to the seal ring 12 of the package body 5, and the package body 5 is sealed to obtain the package 2. In addition, as a joining method of the sealing board 6, seam welding by making a roller electrode contact, laser welding, ultrasonic welding, etc. are mentioned, for example. Moreover, in order to make the welding of the sealing plate 6 and the seal ring 12 more reliable, a bonding layer such as nickel or gold that is familiar to each other is provided at least on the lower surface of the sealing plate 6 and the upper surface of the seal ring 12. It is preferable to form.
Thus, the piezoelectric vibrator 1 according to this embodiment is completed.

  Thus, according to the present embodiment, the first main mask 73 can be disposed on the piezoelectric plate 30 via the first submask 72 formed of an insulating material in the trimming process. For this reason, when the first main mask 73 is formed of a metal material, the first main mask 73 comes into contact with the excitation electrodes 41 and 42 formed on the vibrating arm portions 31 and 32 of the piezoelectric plate 30 and the excitation electrode. 41 and 42 can be prevented from short-circuiting. As a result, even when the first mask 71 is disposed on the piezoelectric plate 30 in order to remove the weight metal film 50, the vibration arms 31 and 32 are vibrated by applying a voltage to the excitation electrodes 41 and 42. Thus, the frequency of the piezoelectric vibrating piece 3 can be measured. Therefore, when the frequency of the piezoelectric vibrating piece 3 is measured, it is not necessary to retract the first mask 71 from the piezoelectric plate 30, so that the manufacturing efficiency can be improved, the frequency can be adjusted with high accuracy, and the vibration characteristics can be adjusted. Can be manufactured.

In the trimming step, the second mask 76 is disposed on the opposite side of the first mask 71 with the piezoelectric plate 30 interposed therebetween, so that the particles of the weight metal film 50 blown off by the ion milling cause the piezoelectric plate 30 to move. It is possible to prevent re-adhering to the piezoelectric plate 30 around the opposite side of the first mask 71 by sandwiching the first mask 71.
Further, since the second mask 76 is provided with openings 77a and 78a that expose the mount electrodes 43 and 44 connected to the excitation electrodes 41 and 42, the first mask 71 and the second mask 76 are piezoelectric plates. The probe of the measuring instrument or the like can be brought into contact with the excitation electrodes 41 and 42 by being brought into contact with the mount electrodes 43 and 44 in a state of being disposed on the electrode 30. This eliminates the need to retract the first mask 71 and the second mask 76 from the piezoelectric plate 30 when measuring the frequency of the piezoelectric vibrating piece 3, thereby preventing a reduction in manufacturing efficiency.

Further, by providing the openings 77a and 78a in the second mask 76, reattachment of the metal film particles to the piezoelectric plate 30 through the openings can be suppressed as compared with the case where the openings are provided in the first mask. In addition, the layout of the opening can be improved.
In addition, since each of the sub masks 72 and 77 is disposed in a region avoiding the surface of the vibrating arm portions 31 and 32, the vibrating arm portions 31 and 32 come into contact with each of the sub masks 72 and 77 in contact with the vibrating arm portions 31 and 32. It is possible to prevent obstructing the vibrations.

  Note that the trimming step may be performed again after the measurement step and before the frequency fine adjustment step. In this case, in this embodiment, since the measurement process can be performed with the first mask 71 disposed, the trimming process is performed again with the first mask 71 disposed, for example, according to the measurement result in the measurement process. Thus, it is possible to adjust the frequency of the piezoelectric vibrating reed 3 with higher accuracy while preventing a decrease in manufacturing efficiency.

  In the above embodiment, the trimming amount of the weight metal film 50 in the trimming step is determined after measuring the frequency of the piezoelectric vibrating piece 3 in advance. However, the present invention is not limited to this, and the trimming step may be performed while measuring the frequency of the piezoelectric vibrating piece 3. According to this method, since the weight metal film 50 can be removed while measuring the frequency of the piezoelectric vibrating piece 3, the frequency of the piezoelectric vibrating piece 3 can be adjusted with high accuracy with respect to a desired frequency.

The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, in the above embodiment, the openings 77a and 78a of the second mask 76 expose the mount electrodes 43 and 44, but the present invention is not limited to this, and the extraction electrodes 45 and 46 may be exposed. In addition, an electrode electrically connected to the mount electrodes 43 and 44 may be formed on the connecting portion 61 and the electrode may be exposed through the openings 77 a and 78 a of the second mask 76.

  Moreover, in the said embodiment, although the 1st submask 72 and the 1st main mask 73 are formed in the different body, it is not limited to this, The 1st submask and the 1st main mask are formed integrally. May be. In this case, the first submask is formed on the first main mask by a photolithography technique or the like, and the first mask in which the first submask and the first main mask are integrated is arranged on the wafer 60 in the mask arranging step. . The same applies to the second mask 76.

In the above embodiment, the weight metal film 50 is removed by ion milling in the frequency coarse adjustment step. However, the present invention is not limited to this, and the weight metal film 50 may be removed by a laser beam or the like.
In the fine frequency adjustment process of the above embodiment, the weight metal film 50 may be removed using the first mask 71 as in the rough frequency adjustment process. In this case, since the piezoelectric vibrating piece 3 is mounted on the package body 5, it is desirable to use the first mask in which the first submask and the first main mask are integrated as described above.
Further, the second mask may be formed of a thin plate made of a resin material.

  In the above embodiment, a so-called tuning fork type vibration piece is described as an example of the piezoelectric vibration piece. However, the present invention is not limited to this. The piezoelectric vibrating piece includes a pair of supporting arm portions extending from the base portion on both sides in the width direction W of the pair of vibrating arm portions, a so-called side arm type vibrating piece, and a pair of supporting arm portions extending from the base portion. A so-called center arm type vibration piece arranged between the vibrating arm portions may be used.

  In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 3 ... Piezoelectric vibrating piece 30 ... Piezoelectric plate 31, 32 ... Vibrating arm part 41, 42 ... Excitation electrode 43, 44 ... Mount electrode (electrode film) 50 ... Weight metal film 71 ... 1st mask 72 ... 1st submask (submask) 73 ... 1st main mask (main mask) 73a ... Opening part 76 ... 2nd mask 77a, 78a ... Opening part (avoidance part)

Claims (4)

A piezoelectric plate having a pair of vibrating arms, formed on the pair of vibrating arms, an excitation electrode that vibrates the vibrating arms when a voltage is applied, and formed on the pair of vibrating arms A method of manufacturing a piezoelectric vibrating piece provided with a weight metal film for frequency adjustment,
A trimming step of removing the weight metal film through the opening using a first mask having an opening in a portion corresponding to the weight metal film forming region of the piezoelectric plate;
The first mask is
A submask formed of an insulating material and disposed on the piezoelectric plate;
A main mask disposed on the opposite side of the piezoelectric plate from the sub mask;
Having
A method of manufacturing a piezoelectric vibrating piece. In the trimming step, ion milling is performed on the weight metal film in a state where the second mask is disposed on the side opposite to the first mask side with the piezoelectric plate interposed therebetween,
The second mask has an avoiding portion that exposes an electrode film connected to the excitation electrode.
The method of manufacturing a piezoelectric vibrating piece according to claim 1. After the trimming step, the measuring step of measuring the frequency of vibration of the pair of vibrating arms,
The method for manufacturing a piezoelectric vibrating piece according to claim 1, wherein: The trimming step is performed while measuring the frequency of the pair of vibrating arms.
The method for manufacturing a piezoelectric vibrating piece according to any one of claims 1 to 3, wherein

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