JP2009147849A - Piezoelectric vibrator manufacturing method, piezoelectric substrate wafer, and piezoelectric vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for collectively and directly bonding all bonding regions between wafers constituting a piezoelectric vibrator wafer. <P>SOLUTION: Each frame part 16 of a crystal substrate wafer 210 has a first recessed groove 18 on one main face 16a side and a second recessed groove 19 on the other main face 16b side to connect between the inside and the outside of each frame part 16. A first electrode 14a led out from an excitation electrode 14 is formed on the first recessed groove 18 while a second electrode 15a led out from an excitation electrode 15 is formed on the second recessed groove 19. One faces 221, 231 of a first lid wafer 220 and a second lid wafer 230 and both main faces 16a, 16b of the crystal substrate wafer 210 are activated. One face 221 of the first lid wafer 220 is directly bonded to one main face 16a of the crystal substrate wafer 210 while one face 231 of the second lid wafer 230 is directly bonded to the other main face 16b of the crystal substrate wafer 210. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a piezoelectric vibrator, a piezoelectric substrate wafer, and a piezoelectric vibrator.

Piezoelectric vibrators used in various electronic devices such as information devices and mobile communication devices are required to be further reduced in size and thickness as electronic devices become smaller. In order to meet this demand, in the piezoelectric vibrator, for example, a manufacturing method that achieves a reduction in size and thickness by devising a joining method and a sealing method between members constituting the piezoelectric vibrator has been studied.
With respect to the above, a rectangular piezoelectric vibrator piece (hereinafter referred to as a piezoelectric substrate) in which a frame portion and a piezoelectric vibrator piece (hereinafter referred to as a vibrating piece section) disposed inside the frame portion are integrally formed, a first lid and a second In the piezoelectric vibrator configured to be bonded to the lid body, the following manufacturing method is known.
Each of the lead electrodes (hereinafter referred to as extraction electrodes) from the first electrode and the second electrode (hereinafter referred to as excitation electrodes) formed on the main surface of the vibrating piece portion of the piezoelectric substrate is connected to one main surface of the frame portion. The piezoelectric substrate is directly bonded to the first lid or the second lid provided with a notch at a location facing the extraction electrode, and the notch is sealed (for example, Patent Document 1).

JP 2006-211411 A

FIG. 7 is a configuration diagram showing a schematic configuration of a piezoelectric vibrator in a wafer state according to the prior art. FIG. 7A is a development view, and FIG. 7B is a perspective view of the first lid body from the bonding surface side with the piezoelectric substrate.
As shown in FIG. 7, in the piezoelectric vibrator 101, the first lid 120 is directly joined to one main surface 112 of the piezoelectric substrate 110, and the second lid 130 is directly joined to the other main surface 113. ing. A two-dot chain line 150 represents a dividing line when the piezoelectric vibrator 101 is divided into pieces.

  In the above manufacturing method, the lead electrodes 114 a and 115 a from the excitation electrodes 114 and 115 of the piezoelectric substrate 110 are respectively formed on the opposing side portions on the one main surface 112 side of the frame portion 116. For this reason, the first lid 120 is provided with the notches 122 at two locations facing the extraction electrodes 114a and 115a of the bonding surface 121, and the bonding surface to the extraction electrodes 114a and 115a at the time of direct bonding. 121 is avoided. Thereby, the joint surface 121 of the first lid 120 is divided into two island-shaped joint surfaces 121a and 121b.

By the way, the direct bonding by the surface activation of the bonding surface activates and bonds at least one of the bonding surfaces of one bonded material and the other bonded material. If the joining surfaces of one material to be joined and the other material to be joined are continuous planes, by joining the materials to be joined together and pressing any part, the joining spreads quickly and the entire area of the joining surface is joined. The
However, when the joining surface of at least one of the materials to be joined is a plane that is divided discontinuously (island-like), the joining range by pressing is one island-like shape having a pressed portion. Stay in the range.
Therefore, in the above case, it is necessary to press and join arbitrary portions for each island-shaped joint surface. Note that the above phenomenon related to the principle of direct bonding is based on the knowledge of the inventors of the present invention.

From this, when the piezoelectric substrate 110 and the first lid 120 are directly joined by surface activation of the one main surface 112 and the joining surfaces 121a and 121b, for example, first of all, the first lid 120 An arbitrary portion of the left half of the outer surface 123 is pressed to directly join the left half of the piezoelectric substrate 110 and the first lid 120. Next, an arbitrary portion of the right half of the outer surface 123 of the first lid 120 is pressed to directly join the right half of the piezoelectric substrate 110 and the first lid 120.
Thereby, the said manufacturing method is joining operation | work for every joined surface 121a, 121b divided | segmented in the case of direct joining because the joining surface 121 of the 1st cover body 120 is divided | segmented into two island shape. Have to do.

  Accordingly, in the above manufacturing method, when a large number of piezoelectric vibrators are formed in a wafer state in the wafer state, the number of pressed joints increases as the number of picks increases, so the number of pressing points increases and the joining work becomes complicated. There is a problem that productivity decreases.

  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 forms or application examples.

  Application Example 1 A method for manufacturing a piezoelectric vibrator according to this application example includes a vibrating piece portion having an excitation electrode formed on a main surface, and a frame portion that surrounds the vibrating piece portion and supports the vibrating piece portion. A piezoelectric substrate comprising: a first lid that covers one main surface side of the piezoelectric substrate; and a second lid that covers the other main surface side of the piezoelectric substrate; A method of manufacturing a piezoelectric vibrator in which a vibrating piece portion of the piezoelectric substrate is disposed in a space between a lid and the second lid, and each of the piezoelectric substrate wafers on which a plurality of the piezoelectric substrates are formed Forming a first concave groove on the one main surface side and a second concave groove on the other main surface side connecting the inner side and the outer side of the frame portion on the frame portion of the piezoelectric substrate; A first lead electrode drawn from the excitation electrode on one main surface side of the vibrating piece portion is formed in the first concave groove, and the other of the vibrating piece portion A frame processing step including a step of forming, in the second concave groove, a second extraction electrode extracted from the excitation electrode on the main surface side of the first surface, and a first in which a plurality of the first lids are formed An activation processing step of activating at least one surface of the lid wafer and the second lid wafer on which a plurality of the second lids are formed and both main surfaces of the piezoelectric substrate wafer; and the piezoelectric substrate The first surface of the first lid wafer is directly bonded to one main surface of the wafer, and the second main surface of the piezoelectric substrate wafer is bonded to the main surface of the second lid wafer. A bonding step of directly bonding one surface subjected to the activation treatment, a sealing step of sealing each of the first concave grooves and each of the second concave grooves of the piezoelectric substrate wafer, and after the sealing step , Piezoelectric vibrator wafers made by directly bonding each wafer are divided into individual piezoelectric vibrators And that dividing step, and having a.

According to this, the piezoelectric vibrator manufacturing method includes a first concave groove on one main surface side connecting the inner side and the outer side of the frame portion to the frame portion of each piezoelectric substrate of the piezoelectric substrate wafer, and the other. A second groove on the main surface side is formed. Then, one surface of the first lid wafer is directly bonded to one main surface of the piezoelectric substrate wafer, and one surface of the second lid wafer is directly bonded to the other main surface.
As a result, in the method for manufacturing a piezoelectric vibrator, the first concave groove of each piezoelectric substrate is formed on one main surface of the piezoelectric substrate wafer, and the second concave groove is formed on the other main surface. The one main surface and the other main surface of the piezoelectric substrate wafer are formed in a continuous state without being divided into a plurality of island shapes by the first concave grooves or the second concave grooves.

Therefore, in the piezoelectric vibrator manufacturing method, the direct bonding of the stacked wafers spreads quickly by pressing any part of one outer surface of the stacked wafers when directly bonding the wafers. Bonding regions can be bonded together.
As a result, the piezoelectric vibrator manufacturing method facilitates the joining work because a large number of piezoelectric vibrators are formed in a lattice shape in the wafer state, and each joining surface is formed in a continuous state even if the number of picks is increased. And productivity is improved.

  In the method for manufacturing a piezoelectric vibrator, the first concave groove of each piezoelectric substrate is formed on one main surface of the piezoelectric substrate wafer, and the second concave groove is formed on the other main surface. From this, the method of manufacturing the piezoelectric vibrator has one main surface side of the piezoelectric substrate wafer at the time of direct bonding as compared with the case where two concave grooves are formed only on one of the main surfaces. It is easy to balance the bonding strength between the main surface and the other main surface. Thereby, the manufacturing method of a piezoelectric vibrator can suppress variation in impact resistance performance depending on the direction in which the impact of the piezoelectric vibrator is applied.

  Application Example 2 In the piezoelectric vibrator manufacturing method according to the application example described above, the first lid wafer has a first concave groove of one frame portion formed on the piezoelectric substrate wafer in a plan view. A plurality of first through holes that overlap with second concave grooves of other frame portions formed adjacent to the one frame portion, and the piezoelectric substrate wafer is adjacent to the one of the first through holes. A plurality of second through holes that cut out the first groove in the frame portion and the second groove in the other frame portion; and the first lid wafer and the piezoelectric substrate wafer in the joining step. Are directly joined so that the first through holes and the second through holes overlap, and after the joining step, in the sealing step, the first through holes and the second through holes are joined. A sealing member is filled in each overlapping portion with the through hole of the first through-hole, and the first concave groove and the second concave groove are formed by the sealing member. It is preferable to stop.

According to this, in the method for manufacturing a piezoelectric vibrator, the first lid wafer is formed adjacent to the first concave groove of the one frame portion formed on the piezoelectric substrate wafer and the one frame portion. A plurality of first through holes that overlap with the second concave grooves of the other frame portions. The piezoelectric substrate wafer includes a plurality of second through holes that cut out the first concave groove of one frame portion and the second concave groove of the other frame portion. Then, the first lid wafer and the piezoelectric substrate wafer are directly bonded so that the first through holes and the second through holes overlap each other. Then, a sealing member is filled in each overlapping portion between each first through hole and each second through hole, and each first groove and each second groove are sealed.
From this, the piezoelectric vibrator manufacturing method fills each overlapping portion of each first through hole and each second through hole with a sealing member, and each adjacent first concave groove and each second By sealing the concave grooves, the adjacent piezoelectric vibrators can be sealed together.

  [Application Example 3] In the piezoelectric vibrator manufacturing method according to the application example described above, the first concave groove and the second concave groove are formed in the corner portion of each frame portion of the piezoelectric substrate wafer in the frame portion machining step. It is preferable to form in a part.

  According to this, in the method for manufacturing a piezoelectric vibrator, the first concave groove and the second concave groove are provided in the corner portion of the frame portion. Thereby, in the method for manufacturing a piezoelectric vibrator, the space for providing the sealing portion and the second through hole for sealing the first concave groove and the second concave groove is secured in the corner portion rather than the side portion. Compared to the case where the first concave groove and the second concave groove are provided in the side portion, it is not necessary to secure the space by protruding the frame portion to the inside. Can be bigger.

  Application Example 4 In the piezoelectric vibrator manufacturing method according to the application example described above, the first lid wafer is placed on the other surface of the first lid wafer and the side wall of each first through hole. In addition, an external connection terminal paired for each of the piezoelectric vibrators is provided, and in the sealing step, each overlapping portion between each of the first through holes and each of the second through holes is electrically conductive. It is preferable to fill the sealing member having properties.

According to this, in the piezoelectric vibrator manufacturing method, the first lid wafer is paired for each piezoelectric vibrator across the other surface and the side wall of each first through hole. A connection terminal is provided, and a conductive sealing member is filled in each overlapping portion of each first through hole and each second through hole.
Therefore, in the method for manufacturing a piezoelectric vibrator, the first sealing part is formed in one of the external connection terminals of the one piezoelectric vibrator and the first concave groove by filling each overlapping portion with the sealing member. And electrically connecting the other external connection terminal of another adjacent piezoelectric vibrator and the second lead electrode formed in the second concave groove, You can do it all at once.

  Application Example 5 In the piezoelectric vibrator manufacturing method according to the application example, the piezoelectric vibrator wafer is divided into the overlapping portions of the first through holes and the second through holes in the dividing step. It is preferable to divide the piezoelectric vibrator into individual pieces along a dividing line that divides.

According to this, a method for manufacturing a piezoelectric vibrator includes: a piezoelectric vibrator wafer having individual piezoelectric vibrations along a dividing line that divides each overlapping portion between each first through hole and each second through hole. Divide into children.
Therefore, in the piezoelectric vibrator manufacturing method, the sealing portion exposed on the side surface of the individual piezoelectric vibrator by dividing along the above dividing line is also used as, for example, a castellation for characteristic inspection or the like. can do.

  [Application Example 6] The piezoelectric vibrator manufacturing method according to the application example described above is a crystal plate in which the first lid wafer, the second lid wafer, and the piezoelectric substrate wafer are cut at the same cut angle. In the bonding step, it is preferable that the first lid wafer, the second lid wafer, and the piezoelectric substrate wafer are directly bonded in the same direction.

  According to this, the piezoelectric vibrator manufacturing method is a quartz plate in which each wafer is cut at the same cut angle, and in the bonding process, each wafer is directly bonded in the same direction. There is no generation of stress on the piezoelectric substrate wafer when the temperature changes due to the difference in coefficients. Therefore, the method for manufacturing a piezoelectric vibrator can provide a piezoelectric vibrator having excellent temperature characteristics with little change in oscillation frequency due to temperature change.

  Application Example 7 A piezoelectric substrate wafer according to this application example includes a vibrating piece portion having an excitation electrode formed on a main surface, and a frame portion surrounding the vibrating piece portion and supporting the vibrating piece portion. A plurality of piezoelectric substrates provided, a first lid wafer on which a plurality of first lids covering one main surface side of the piezoelectric substrate are formed, and a second lid covering the other main surface side of the piezoelectric substrate. A plurality of lids are directly bonded to the second lid wafer, and each piezoelectric substrate vibrating piece is disposed in a space between the first lid wafer and the second lid wafer. A piezoelectric substrate wafer on which the first main groove side is connected to the frame portion of each of the piezoelectric substrates, and the other main main surface side. A first lead electrode formed with a second concave groove on the surface side and drawn from the excitation electrode on one main surface side of the vibrating piece portion A second extraction electrode formed in the first concave groove and extracted from the excitation electrode on the other main surface side of the vibrating piece portion is formed in the second concave groove. .

According to this configuration, in the piezoelectric substrate wafer, the first concave groove on one main surface side connecting the inner side and the outer side of the frame portion to the frame portion of each piezoelectric substrate, and the second groove on the other main surface side. Are formed. Then, one surface of the first lid wafer is directly bonded to one main surface of the piezoelectric substrate wafer, and one surface of the second lid wafer is directly bonded to the other main surface.
As a result, the piezoelectric substrate wafer has the first concave groove of each piezoelectric substrate formed on one main surface of the piezoelectric substrate wafer and the second concave groove formed on the other main surface. The main surface and the other main surface are formed in a continuous state without being divided into island shapes by the first groove or the second groove.

  Therefore, the direct bonding of the piezoelectric substrate wafer to the stacked wafer can be performed quickly by pressing any part of the outer surface of the piezoelectric substrate wafer or the stacked wafer during direct bonding to each wafer. It is possible to spread and join all the joining regions together.

  In addition, the piezoelectric substrate wafer has a first concave groove of each piezoelectric substrate formed on one main surface of the piezoelectric substrate wafer, and a second concave groove formed on the other main surface. Therefore, in comparison with the case where two concave grooves are formed only on one of the main surfaces, the piezoelectric substrate wafer has one main surface of the piezoelectric substrate wafer when directly bonded to another wafer. It is easy to balance the bonding strength between the surface side and the other main surface side.

  Application Example 8 A piezoelectric vibrator according to this application example is manufactured by the manufacturing method described in the application example.

  According to this, since the piezoelectric vibrator is manufactured by the manufacturing method described in the above application example, one main surface and the other main surface of the piezoelectric substrate in a wafer state may be divided into island shapes. And formed in a continuous state. Therefore, in the piezoelectric vibrator, direct bonding between the piezoelectric substrate and each lid body in the wafer state spreads quickly, and all the bonding regions of each bonding surface can be bonded together.

  Hereinafter, embodiments of a piezoelectric vibrator manufacturing method, a piezoelectric substrate wafer, and a piezoelectric vibrator will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a configuration diagram illustrating a schematic configuration of a crystal resonator as an example of a piezoelectric resonator. FIG. 1A is an external perspective view, and FIG. 1B is a developed perspective view.
FIG. 2 is a cross-sectional view of the crystal unit shown in FIG. 2A is a cross-sectional view taken along line AA in FIG. 1A, and FIG. 2B is a cross-sectional view taken along line BB in FIG.

As shown in FIGS. 1 and 2, the crystal resonator 1 includes a crystal substrate 10 as a piezoelectric substrate, a first lid body 20, a second lid body 30, and the like. The quartz substrate 10, the first lid 20, and the second lid 30 are all quartz plates that are cut out from a quartz crystal with the same cut angle and are arranged in the same direction. In the present embodiment, both are formed from an AT-cut quartz plate cut at an AT-cut angle. The front and back surfaces of all three parts are finished in a mirror surface state with a predetermined surface roughness.
In addition, all three parts are formed in a rectangular wafer shape with a size of several hundred pieces, and after predetermined processing, the crystal substrate 10 is joined to the first lid 20 and the second lid 30 by direct joining. Is done. Then, predetermined processing is performed and it cuts out into a piece. The details of the manufacturing method of the crystal unit 1 will be described later.

The quartz substrate 10 includes a vibrating piece portion 11 and a substantially rectangular frame portion 16 that surrounds the vibrating piece portion 11 and supports the vibrating piece portion 11 via the arm portions 17a and 17b.
An excitation electrode 14 is formed on one main surface 12 of the resonator element 11 of the quartz substrate 10, and an excitation electrode 15 is formed on the other main surface 13.

The frame portion 16 of the quartz substrate 10 has a first groove 18 on one main surface 16a side and a second groove 19 on the other main surface 16b side that connects the inside and the outside of the frame portion 16 to each other. Is formed in the corner portion 16e. In addition, the inner side wall shape of the frame portion 16 is formed in a slope shape in which the thickness decreases as it goes inward on both sides of the front side (one main surface 16a side) and the back side (the other main surface 16b side), The cross section is wedge-shaped.
In the first concave groove 18 of the frame portion 16, a first extraction electrode 14a extracted from the excitation electrode 14 on the one main surface 12 of the vibration piece portion 11 is formed via the arm portion 17a. . In the second concave groove 19, the second lead electrode 15 a drawn from the excitation electrode 15 on the other main surface 13 of the vibrating piece portion 11 passes through the arm portion 17 b and the side wall 16 c inside the frame portion 16. Is formed.
In addition, a cutout portion 16d having a circular arc shape is formed at the corner portion 16e of the frame portion 16.

  The excitation electrodes 14 and 15 are subjected to gold sputtering or the like of chrome (others such as titanium or nichrome). Further, the side surfaces of the lead electrodes 14a and 15a and the cutout portion 16d are further subjected to nickel, gold plating, chromium, nickel, gold sputtering, or the like on a chromium sputter of chromium (others such as titanium or nichrome).

  In the quartz substrate 10, the thickness of the frame portion 16 is set to about 60 to 100 μm, and the thickness of the vibrating piece portion 11 is appropriately set in the range of several μm to several tens of μm according to a predetermined oscillation frequency.

The first lid 20 is a substantially rectangular flat plate having a thickness of about 100 to 200 μm, and the corner portion has a circular arc shape in the plane and has a small cut amount on one surface 21 side, and the other surface 23 side. A notch 22 having a large amount of cut is formed.
One surface 21 of the first lid 20 is a joint surface with one main surface 16 a of the quartz substrate 10. The first lid 20 is formed with a pair of external connection terminals 24 a and 24 b across the other surface 23 and the inclined side wall 22 a of the notch 22.

The external connection terminals 24a and 24b are formed by sputtering or the like using a metal such as chromium, nickel, gold, aluminum, titanium, or nichrome. The external connection terminals 24a and 24b are further plated with gold on a base plating such as nickel.
A metal such as chromium, nickel, or gold is formed on the side wall 22a by sputtering or vapor deposition, or a metal film such as nickel or gold is formed on the chromium and gold base film formed by sputtering.

  The second lid 30 is a rectangular flat plate having a thickness of about 100 to 200 μm, and one surface 31 is a joint surface with the other main surface 16 b of the quartz substrate 10.

The quartz resonator 1 includes a first lid 20 that covers the quartz substrate 10 on one main surface 16a side and a second lid 30 that covers the other principal surface 16b side of the quartz substrate 10. In the space between the first lid body 20 and the second lid body 30, the vibrating piece portion 11 of the crystal substrate 10 is disposed.
In the crystal resonator 1, one surface 21 of the first lid 20 and one main surface 16 a of the crystal substrate 10 are directly bonded, and one surface 31 of the second lid 30 and the other surface of the crystal substrate 10. The main surface 16b is directly joined.

After the joining, the crystal unit 1 is formed on one surface 31 of the second lid 30, the notch 16 d of the frame portion 16 of the quartz substrate 10, and the notch 22 of the first lid 20. The conductive sealing member 40 is filled over the first groove 18 and the second groove 19 are sealed.
At the same time, in the crystal resonator 1, the first lead electrode 14 a formed in the first concave groove 18 is electrically connected to one external connection terminal 24 a via the conductive sealing member 40. The second lead electrode 15a formed in the second concave groove 19 is electrically connected to the other external connection terminal 24b. The conductive sealing member 40 is made of a low melting point metal such as solder or an alloy of gold and germanium.
The inside of the crystal unit 1 is hermetically sealed by a conductive sealing member 40. Note that the inside of the crystal unit 1 is sealed with a vacuum or an inert gas such as nitrogen, helium, or argon.

  When the driving voltage is applied to the excitation electrodes 14 and 15 from the outside via the external connection terminals 24a and 24b, the crystal resonator 1 configured in this manner oscillates thickness shear vibration.

  As described above, in the crystal resonator 1 of the present embodiment, the first concave groove 18 of the crystal substrate 10 is formed on the one main surface 16 a of the frame portion 16, and the second concave groove 19 is formed on the frame portion 16. It is formed on the other main surface 16b. As a result, the crystal unit 1 has a bonding strength between one main surface 16 a of the crystal substrate 10 and one surface 21 of the first lid 20, and one of the other main surface 16 b and the second lid 30. It becomes easy to balance the bonding strength with the surface 31. From this, the crystal unit 1 can suppress variations in impact resistance depending on the direction in which the impact is applied.

The quartz resonator 1 is a quartz plate in which the first lid 20, the second lid 30 and the quartz substrate 10 are cut out at the same cut angle, and these components are directly joined in the same orientation. Has been.
For this reason, the crystal resonator 1 does not generate stress on the crystal substrate 10 at the time of temperature change due to the difference in the linear expansion coefficient of each component. Therefore, the crystal unit 1 has a small change in oscillation frequency due to a change in temperature and is excellent in temperature characteristics.

  Further, in the crystal resonator 1, the first concave groove 18, the second concave groove 19, the cutout portion 16d of the crystal substrate 10 and the cutout portion 22 of the first lid 20 are easily cornered. It is provided in the part 16e. As a result, the crystal resonator 1 does not have to secure the space by protruding the frame portion 16 inward as compared with the case where the above portions are provided on the side portion 16f. The piece 11 can be enlarged.

  In the quartz resonator 1, the first concave groove 18, the second concave groove 19, the cutout portion 16d, and the cutout portion 22 of the first lid 20 of the quartz substrate 10 are not the corner portion 16e. You may provide in the side part 16f. According to this, compared with the case where each part is provided in the corner portion 16e, the crystal resonator 1 is less likely to collide with the external member when dropped or the like, and the impact resistance is improved.

  Further, since the sealing member 40 is exposed on the side surface of the corner portion 16e, the crystal unit 1 also uses the sealing member 40 portion as a castellation for visual inspection when mounted on an external member. be able to.

Here, a manufacturing method of the crystal unit 1 will be described with reference to the following drawings and FIGS.
3 to 6 are explanatory views schematically showing a method for manufacturing a crystal resonator. FIG. 3 is a developed perspective view showing the main components of the crystal resonator wafer as a piezoelectric resonator wafer on which a plurality of crystal resonators are formed.
FIG. 4A is a perspective view showing a direct bonding state of a crystal resonator wafer, and FIG. 4B is a perspective view showing a formation state of external connection terminals.
FIG. 5A is a perspective view showing an insertion state of the sealing member, and FIG. 5B is a perspective view showing a filling state of the sealing member and a dividing line for dividing the crystal wafer into individual crystal vibrators. FIG.
6A is a cross-sectional view taken along the line C-C in FIG. 5B, and FIG. 6B is a diagram illustrating a state in which the shape of the component parts of the crystal resonator wafer is changed to another shape. It is sectional drawing in CC line of 5 (b).

  The outline of the manufacturing method of the crystal unit 1 is as follows: a first lid wafer 220 in which a plurality of first lids 20 are formed on a quartz substrate wafer 210 as a piezoelectric substrate wafer in which a plurality of quartz substrates 10 are formed; The second lid wafer 230 formed with a plurality of the two lid bodies 30 is directly joined. Then, the opening is sealed and divided into individual pieces. Hereinafter, the manufacturing method of the crystal unit 1 will be described in detail for each step.

  First, an AT-cut quartz plate cut out in a wafer shape from an original quartz crystal at an AT-cut angle is used as a quartz substrate wafer 210, a first lid wafer 220, and a second lid wafer 230, each with a prescribed thickness. Finish with a polishing machine to a mirror-finished surface roughness.

"Frame processing process"
Next, as shown in FIG. 3, in the quartz substrate wafer 210, after adjusting the parallelism of the front and back surfaces, the frame portion 16, the vibrating piece portion 11, and the arm portions 17a and 17b are formed by a method such as photolithography and etching. The range surrounded by the two-dot chain line in FIG. 3 is the range of one crystal substrate 10, and the two-dot chain line part is the outer shape of the frame portion 16. Formed on wafer 210. In addition, the vibration piece part 11 side in each frame part 16 is an inside, and the connection side with the other frame part 16 is an outside.
In FIG. 3, the quartz substrate 10 formed on the outer peripheral portion of the quartz substrate wafer 210 is omitted, and the range display of the other quartz substrate 10 (frame portion 16) by a two-dot chain line is also omitted so as not to be complicated. It is.

  Next, in the same manner as described above, the first concave groove 18 is formed on one main surface 16a of the corner portion 16e of the frame portion 16 so as to connect the inside and the outside of the frame portion 16, and the other main surface. A second concave groove 19 is formed in 16 b so as to connect the inner side and the outer side of the frame portion 16.

  Next, in the same manner as described above, the first concave groove 18 of one frame portion 16 and the second concave groove of another frame portion 16 formed adjacent to the one frame portion 16 in plan view. A circular second through hole 250 is formed in each corner portion 16e. The second through hole 250 serves as a notch 16d in the individual quartz substrate 10. Note that the order of the above forming operations may be changed. The shape of the second through hole 250 may be an ellipse, a rectangle, a polygon, or the like.

  Next, the excitation electrodes 14 and 15 are formed on the vibration piece portion 11 by a film formation method such as sputtering or plating, and the first extraction electrode 14a is formed in the first groove 18 via the arm portion 17a. The second lead electrode 15a is formed in the second concave groove 19 via the arm portion 17b and the side wall 16c inside the frame portion 16. In addition, a metal film is formed on the side wall of the second through hole 250 by the same method. This metal film is used for measuring the oscillation frequency of the resonator element 11.

After the frame processing step, the oscillation frequency of the resonator element 11 is adjusted by a small amount of etching of the excitation electrodes 14 and 15.
The first lid wafer 220 is formed adjacent to the first concave groove 18 of the one frame portion 16 formed in the quartz substrate wafer 210 and the one frame portion 16 in plan view. The required number of first through holes 260 that overlap with the second concave grooves 19 of the other frame portions 16 (overlap with the second through holes 250 of the quartz substrate wafer 210) are formed by a method such as sandblasting. The first through-hole 260 serves as the cutout portion 22 in the individual first lid body 20. The shape of the first through hole 260 may be an ellipse, a rectangle, a polygon, or the like.
In the second lid wafer 230, the process proceeds to the activation process at the stage where the mirror surface is finished with a predetermined thickness and a predetermined surface roughness.

"Activation process"
Next, an oxygen gas is supplied into the vacuum chamber using an irradiation apparatus (not shown), and a high frequency voltage is applied to generate oxygen plasma, so that one surface 221 of the first lid wafer 220 and the second lid body are generated. One surface 231 of the wafer 230 is irradiated with oxygen plasma. Next, nitrogen plasma is generated using a nitrogen gas in the same manner, nitrogen ions are removed and nitrogen radical irradiation is performed, and one surface 221 of the first lid wafer 220 and one of the second lid wafer 230 are irradiated. The surface 231 is activated.

  Next, both main surfaces 16a and 16b of the quartz substrate wafer 210 are activated by nitrogen radical irradiation. It should be noted that both the main surfaces 16a and 16b of the quartz substrate wafer 210 may be hydrophilized by immersing in sulfuric acid / hydrogen peroxide instead of nitrogen radical irradiation.

"Joining process"
Next, as shown in FIG. 3 and FIG. 4A, the second lid wafer 230 is placed on a work table or the like with the other surface 232 serving as a placement surface in a non-pressurized state at room temperature. Then, the other main surface 16 b of the quartz substrate wafer 210 is superimposed on one surface 231 of the second lid wafer 230.
Next, an arbitrary portion of one main surface 16a of the quartz substrate wafer 210 is pressed. At this time, the other main surface 16b of the quartz substrate wafer 210 is formed in a continuous state in the entire region without being divided into a plurality of island shapes.
Thereby, the direct bonding of the two surfaces 231 and 16b spreads quickly, and the one surface 231 of the second lid wafer 230 and the other main surface 16b of the quartz substrate wafer 210 are directly bonded over the entire bonding region. The

Then, one main surface 16a of the quartz substrate wafer 210 is provided with one surface 221 of the first lid wafer 220, the first through-hole 260 of the first lid wafer 220, and the second surface of the quartz substrate wafer 210. The through holes 250 are overlapped with each other.
Then, an arbitrary portion of the other surface 223 of the first lid wafer 220 is pressed as indicated by an arrow in FIG. At this time, one main surface 16a of the quartz substrate wafer 210 is formed in a continuous state in the entire region without being divided into a plurality of islands.
Thereby, the direct bonding of the two surfaces 221 and 16a spreads quickly, and the one main surface 16a of the quartz substrate wafer 210 and the one surface 221 of the first lid wafer 220 are directly bonded over the entire bonding region. The In addition, if the whole wafer is pressed uniformly with a press after bonding, the bondability is further improved.

After bonding, annealing is performed at 200 ° C. for 2 hours or more. As a result, a crystal resonator wafer 201 in which the respective wafers are directly bonded is obtained.
The superposition operation is preferably performed in the atmosphere, but can also be performed in a vacuum or in an inert gas.

After the bonding step, as shown in FIG. 4B, the other surface 223 of the first lid wafer 220 and the side wall 222 of each first through hole 260 are formed by a film forming method such as sputtering or plating. A pair of external connection terminals 24a and 24b is formed for each crystal resonator 1.
In FIG. 1, FIG. 2, and FIG. 6, when forming the external connection terminals 24a and 24b, the metal film attached to other portions is omitted.

"Sealing process"
Next, as shown in FIG. 5A, a metal that becomes a sealing member 40 having conductivity when divided into each crystal resonator 1 in each first through-hole 260 of the first lid wafer 220. Insert the ball 240. The metal ball 240 is made of a low melting point metal such as solder or an alloy of gold and germanium.

  Then, a metal ball 240 is melted by irradiating a YAG (Yttrium Aluminum Garnet) laser, a semiconductor laser, a halogen lamp, or the like (not shown), and filled into the quartz vibrator wafer 201 from each first through hole 260. At this time, as shown in FIG. 6A, the melted metal balls 240 are filled in the overlapping portions 270 of the first through holes 260 and the second through holes 250 of the quartz substrate wafer 210, Each first groove 18 and each second groove 19 are sealed.

  As a result, the external connection terminal 24a and the first lead electrode 14a formed in the first concave groove 18 are electrically connected to each other through the melted metal ball 240, The external connection terminal 24b and the second lead electrode 15a formed in the second concave groove 19 are electrically connected to another adjacent crystal unit.

"Division process"
Next, as shown in FIGS. 5B and 6A, the crystal resonator wafer 201 is divided so as to divide each overlapping portion 270 between each first through hole 260 and each second through hole 250. The crystal unit 1 shown in FIG. 1 is obtained by dividing the crystal unit 1 into individual crystal units 1 by dicing along the line L. After that, various reliability evaluations and inspections are performed.

  As described above, the method for manufacturing the crystal resonator 1 according to the present embodiment (hereinafter referred to as the present manufacturing method) connects each frame portion 16 of the quartz substrate wafer 210 to the inside and the outside of each frame portion 16. The first groove 18 on the main surface 16a side and the second groove 19 on the other main surface 16b side are formed. Then, one surface 221 of the first lid wafer 220 is directly bonded to one main surface 16a of the quartz substrate wafer 210, and one surface 231 of the second lid wafer 230 is bonded to the other main surface 16b. Are joined directly.

  Thus, in the present manufacturing method, each first concave groove 18 is formed on one main surface 16a of the quartz substrate wafer 210, and each second concave groove 19 is formed on the other main surface 16b. The main surface 16a and the other main surface 16b of the quartz substrate wafer 210 are formed in a continuous state without being divided into a plurality of island shapes by the first concave grooves 18 or the second concave grooves 19. ing.

Therefore, in the present manufacturing method, one main surface 16a of the quartz substrate wafer 210 is directly bonded to one surface 231 of the second lid wafer 230 and the other main surface 16b of the quartz substrate wafer 210. By directly pressing any part of the wafer, direct bonding between the one surface 231 of the second lid wafer 230 and the other main surface 16b of the quartz substrate wafer 210 spreads quickly, and all the bonding regions are bonded together. be able to.
In addition, the direct bonding of the first lid wafer 220 and the quartz substrate wafer 210 can be performed by pressing any part of the other surface 223 of the first lid wafer 220 in the same manner as described above. Can be joined together.

  As a result, in this manufacturing method, a large number of crystal resonators 1 are formed in a wafer state in a wafer state, and even if the number is increased, each bonding surface is formed in a continuous state. It becomes easy and productivity improves.

  Further, in this manufacturing method, each first groove 18 is formed on one main surface 16a of the quartz substrate wafer 210, and each second groove 19 is formed on the other main surface 16b. Therefore, in this manufacturing method, compared with the case where the two concave grooves 18 and 19 are formed only on one of the main surfaces 16a (16b), the quartz substrate wafer 210 is directly bonded. It is easy to balance the bonding strength between the one main surface 16a side and the other main surface 16b side. Thereby, this manufacturing method can suppress the dispersion | variation in the impact resistance performance by the direction where the impact of the crystal oscillator 1 is added.

  Further, in the present manufacturing method, the metal ball 240 is melted and filled in each overlapping portion 270 between each first through hole 260 and each second through hole 250, so that each first concave groove 18 and each each By sealing each second groove 19 adjacent to the first groove 18, the adjacent crystal units 1 can be sealed together.

  Further, in the present manufacturing method, the first ball formed in the external connection terminal 24a and the first concave groove 18 of one crystal resonator 1 is obtained by melting and filling the metal ball 240 in each overlapping portion 270. The lead electrode 14a is electrically connected, and the external connection terminal 24b of another adjacent crystal resonator 1 and the second lead electrode 15a formed in the second groove 19 are electrically connected. But you can do it all at once.

  Further, in the present manufacturing method, the crystal resonator wafer 201 is divided into the individual crystal resonators 1 along the dividing line L that divides each overlapping portion 270, so that it is exposed to the side surface of each crystal resonator 1. The sealed sealing member 40 can be used as a castellation for characteristic inspection or the like when mounted on an external member.

  In addition, this manufacturing method is a crystal plate in which each wafer is cut at the same cut angle, and each wafer is directly bonded in the same direction in the bonding process, which is caused by a difference in linear expansion coefficient of each wafer. There is no generation of stress in the quartz substrate wafer 210 when the temperature changes. Therefore, the present manufacturing method can provide the crystal resonator 1 having excellent temperature characteristics with little change in oscillation frequency due to temperature change.

In this manufacturing method, oxygen plasma irradiation and nitrogen radical irradiation were performed on one surface 221 of the first lid wafer 220 and one surface 231 of the second lid wafer 230 in the activation process. However, the present invention is not limited to this, and only oxygen plasma irradiation or nitrogen radical irradiation may be used. Moreover, you may irradiate oxygen radical after that.
Moreover, although nitrogen radical irradiation was performed to both main surface 16a, 16b of the quartz substrate wafer 210, it is not limited to this, Oxygen radical irradiation may be sufficient and both nitrogen radical irradiation and oxygen radical irradiation may be performed. . In either case, each bonding surface is activated by the attachment of oxygen or nitrogen ions or radicals.

In addition, the procedure of direct bonding of each wafer in the bonding process of this manufacturing method is not limited to the above procedure. For example, the quartz substrate wafer 210 is placed on a work table or the like so that one principal surface 16a becomes a placement surface, and one of the second lid wafers 230 is placed on the other principal surface 16b of the quartz substrate wafer 210. The surface 231 is overlapped. Then, an arbitrary portion of the other surface 232 of the second lid wafer 230 is pressed to directly bond one surface 231 of the second lid wafer 230 and the other main surface 16b of the quartz substrate wafer 210. May be.
Further, the quartz substrate wafer 210 and the first lid wafer 220 may be directly bonded first, or the respective wafers may be directly bonded together.

  In this manufacturing method, the external connection terminals 24a and 24b of the first lid wafer 220 are formed after the joining step, but the present invention is not limited to this, and may be formed before the joining step. At this time, as shown in FIG. 6B, the diameter D2 of each second through-hole 350 of the crystal substrate wafer 310 of the crystal resonator wafer 301 is set to each first through-hole of the first lid wafer 220. It is formed larger than the diameter D1 of 260.

  Thereby, this manufacturing method avoids the wraparound portion to the one surface 221 side of the external connection terminals 24a and 24b when the external connection terminals 24a and 24b are formed on the first lid wafer 220 before the bonding step. Thus, the one surface 221 of the first lid wafer 220 can be directly bonded to the one main surface 16 a of the quartz substrate wafer 310.

  As described in the above description of the manufacturing method, in the quartz substrate wafer 210 of the present embodiment, each first groove 18 is formed on one main surface 16a, and each second groove 19 is the other. The main surface 16b is formed. Thereby, the quartz substrate wafer 210 is in a state in which one main surface 16a and the other main surface 16b are not divided into a plurality of island shapes by the first groove 18 or the second groove 19 in a continuous state. It is formed.

  Therefore, when the quartz substrate wafer 210 is directly bonded to another wafer, the quartz substrate wafer 210 is pressed to any other part of the outer surface of the quartz substrate wafer 210 or the other wafer so as to overlap the other wafer. The direct bonding to and quickly spreads, and the entire bonding area can be bonded together.

  Further, in the quartz substrate wafer 210, each first concave groove 18 is formed on one main surface 16a, and each second concave groove 19 is formed on the other main surface 16b. Thereby, when the quartz substrate wafer 210 is directly bonded to another wafer as compared with the case where the two concave grooves 18 and 19 are formed only on one of the main surfaces 16a (16b), It is easy to balance the bonding strength between the one main surface 16a side and the other main surface 16b side of the quartz substrate wafer 210.

  In this embodiment, the quartz substrate wafer 210 as the piezoelectric substrate wafer is an AT-cut quartz plate. However, the present invention is not limited to this, and may be a lithium tantalate substrate, a lithium niobate substrate, or the like. Further, although the first lid wafer 220 and the second lid wafer 230 are AT-cut quartz plates, the present invention is not limited to this, and glass plates or the like may be used. When a glass plate is used, it is preferable to form a thin film such as TEOS (Tetraethoxysilane) or amorphous silicon on the bonding surface of the glass plate in order to assist direct bonding.

The block diagram which shows schematic structure of the crystal oscillator of this embodiment. Sectional drawing of the crystal oscillator of this embodiment. Explanatory drawing which showed typically about the manufacturing method of the crystal oscillator of this embodiment. Explanatory drawing which showed typically about the manufacturing method of the crystal oscillator of this embodiment. Explanatory drawing which showed typically about the manufacturing method of the crystal oscillator of this embodiment. Explanatory drawing which showed typically about the manufacturing method of the crystal oscillator of this embodiment. The block diagram which shows schematic structure of the piezoelectric vibrator in the wafer state of a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Vibrating piece part, 14, 15 ... Excitation electrode, 14a ... 1st extraction electrode, 15a ... 2nd extraction electrode, 16 ... Each frame part of quartz substrate wafer, 16a ... One main surface of quartz substrate wafer, 16b ... the other main surface of the quartz substrate wafer, 17a, 17b ... arms, 18 ... first concave groove, 19 ... second concave groove, 210 ... quartz substrate wafer as piezoelectric substrate wafer, 220 ... first Lid wafer, 221... One surface of the first lid wafer, 230... Second lid wafer, 231.

Claims (8)

A piezoelectric substrate comprising a vibrating piece portion having an excitation electrode formed on a main surface and a frame portion surrounding the vibrating piece portion and supporting the vibrating piece portion is provided on one main surface side of the piezoelectric substrate. A first lid that covers and a second lid that covers the other main surface side of the piezoelectric substrate are joined to each other, and the piezoelectric is placed in a space between the first lid and the second lid. A method of manufacturing a piezoelectric vibrator in which a vibrating piece portion of a substrate is disposed,
The first concave groove on the one main surface side connecting the inner side and the outer side of the frame portion to the frame portion of each piezoelectric substrate of the piezoelectric substrate wafer on which a plurality of the piezoelectric substrates are formed, and the other main substrate side A second lead groove on the surface side is formed, and a first lead electrode drawn from the excitation electrode on one main surface side of the vibrating piece portion is formed in the first groove, and the vibration A frame processing step including a step of forming, in the second concave groove, a second extraction electrode extracted from the excitation electrode on the other main surface side of the one portion;
At least one surface of a first lid wafer having a plurality of the first lids and a second lid wafer having a plurality of the second lids, and both main surfaces of the piezoelectric substrate wafer. An activation treatment step for activation treatment;
The first surface of the first lid wafer is directly bonded to one main surface of the piezoelectric substrate wafer, and the second lid is bonded to the other main surface of the piezoelectric substrate wafer. A bonding step of directly bonding the activated one side of the wafer;
A sealing step of sealing each of the first and second concave grooves of the piezoelectric substrate wafer;
A method of manufacturing a piezoelectric vibrator, comprising: a step of dividing a piezoelectric vibrator wafer formed by directly bonding the wafers into individual piezoelectric vibrators after the sealing step. 2. The method for manufacturing a piezoelectric vibrator according to claim 1, wherein the first lid wafer has a first concave groove of one frame portion formed on the piezoelectric substrate wafer in a plan view, and the first lid wafer. A plurality of first through holes that overlap with the second concave groove of another frame portion formed adjacent to the frame portion,
The piezoelectric substrate wafer includes a plurality of second through holes that cut out the first concave groove of the adjacent one frame portion and the second concave groove of the other frame portion in plan view,
In the bonding step, the first lid wafer and the piezoelectric substrate wafer are directly bonded so that the first through holes and the second through holes overlap with each other,
After the joining step, in the sealing step, a sealing member is filled in each overlapping portion of each first through hole and each second through hole, and each first recess is filled by the sealing member. A method for manufacturing a piezoelectric vibrator, wherein the groove and each of the second concave grooves are sealed.   3. The method for manufacturing a piezoelectric vibrator according to claim 1, wherein in the frame portion machining step, the first concave groove and the second concave groove are arranged at corners of the respective frame portions of the piezoelectric substrate wafer. A method for manufacturing a piezoelectric vibrator, characterized in that the piezoelectric vibrator is formed on a portion. 4. The method of manufacturing a piezoelectric vibrator according to claim 2, wherein the first lid wafer is formed on the other surface of the first lid wafer and a sidewall of each first through hole. In addition, each piezoelectric vibrator is provided with a pair of external connection terminals,
In the sealing step, the electrically conductive sealing member is filled in each overlapping portion between each of the first through holes and each of the second through holes. .   5. The method for manufacturing a piezoelectric vibrator according to claim 2, wherein the piezoelectric vibrator wafer is divided into the first through holes and the second through holes in the dividing step. A method of manufacturing a piezoelectric vibrator, comprising: dividing the piezoelectric vibrator into individual piezoelectric vibrators along a dividing line that divides each of the overlapping portions. 5. The method for manufacturing a piezoelectric vibrator according to claim 1, wherein the first lid wafer, the second lid wafer, and the piezoelectric substrate wafer are cut out at the same cut angle. A crystal plate,
In the bonding step, the first lid wafer, the second lid wafer, and the piezoelectric substrate wafer are directly bonded in the same direction. A plurality of piezoelectric substrates each including a vibrating piece portion having an excitation electrode formed on a main surface and a frame portion surrounding the vibrating piece portion and supporting the vibrating piece portion are formed. A first lid wafer formed with a plurality of first lid bodies covering the surface side, and a second lid wafer formed with a plurality of second lid bodies covering the other main surface side of the piezoelectric substrate. A piezoelectric substrate wafer that is bonded directly between the first lid wafer and the second lid wafer, and wherein the vibrating piece portion of each piezoelectric substrate is disposed in a space between the first lid wafer and the second lid wafer,
A first concave groove on the one main surface side and a second concave groove on the other main surface side that connect the inner side and the outer side of the frame portion are formed in the frame portion of each piezoelectric substrate. ,
A first extraction electrode extracted from the excitation electrode on one main surface side of the vibration piece is formed in the first concave groove;
A piezoelectric substrate wafer, wherein a second extraction electrode extracted from the excitation electrode on the other main surface side of the vibration piece is formed in the second concave groove.   A piezoelectric vibrator manufactured by the manufacturing method according to claim 1.

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