JP5152542B2 - Quartz wafer manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing a piezoelectric wafer, in particular a method for manufacturing a good piezoelectric wafer to take folding a piezoelectric substrate from the piezoelectric wafer body.

  Conventionally, a piezoelectric substrate is obtained as follows. FIG. 5 is an enlarged explanatory view of a part of a piezoelectric wafer according to the prior art. Here, the upper diagram of FIG. 5 is an enlarged plan view of one piezoelectric substrate formed on the piezoelectric wafer. Further, the figure shown in the circle on the lower side of FIG. 5 is an enlarged perspective view of the portion shown in the circle in the plan view.

  A plurality of piezoelectric substrates 102 are formed on one piezoelectric wafer 101 by etching. That is, a protective film corresponding to the shape of the piezoelectric substrate 102 or the like is formed on the upper surface and the lower surface of the piezoelectric wafer 101, and this is immersed in an etching solution to remove portions other than the portion where the piezoelectric substrate 102 or the like is formed. 102 is formed. Each piezoelectric substrate 102 is connected to the piezoelectric wafer body 112 by support portions 111 connected to both ends of a surface (base end surface) 104 provided on the base end 103 side. A groove 105 along the base end face 104 of the piezoelectric substrate 102 is formed in the support portion 111 at a location where it is connected to the piezoelectric substrate 102. The groove 105 does not penetrate from the upper surface to the lower surface of the piezoelectric wafer 101, and the support portion 111 and the piezoelectric substrate 102 are connected in the vicinity of the central portion in the thickness direction. The groove 105 is a cut when the piezoelectric substrate 102 is folded from the piezoelectric wafer body 112. If the groove 105 is not provided, the piezoelectric substrate 102 cannot be beautifully folded from the piezoelectric wafer body 112. That is, it may be broken at a place where the support portion 111 and the piezoelectric wafer body 112 are connected, or may be broken at a place inside the piezoelectric substrate 102.

  Patent Document 1 discloses a method of individually separating crystal pieces produced by photolithography by etching. In the invention disclosed in Patent Document 1, a groove for dynamically weakening at least a part of a quartz wafer is provided in the vicinity of the breakout edge of the quartz piece. By providing this groove, it can be cut cleanly when a bending force is applied to the crystal piece.

Japanese National Patent Publication No. 11-509052

FIG. 6 is an explanatory view of entering after etching. Here, FIG. 6A is a plan view of the piezoelectric substrate formed on the piezoelectric wafer, and FIG. 6B is a cross-sectional view taken along the line AA of FIG. When the piezoelectric wafer 101 is etched to form the piezoelectric substrate 102 shown in FIG. 5, the side surface 107 is etched along the −X direction from the corner portion 106 of the base end 103 of the piezoelectric substrate 102 shown in FIG. . That is, the intrusion 108 is caused by etching toward the inside of the piezoelectric substrate 102. In FIG. 6A, the hatched portion indicates the intrusion 108. When AT-cut quartz is used for the piezoelectric substrate 102, the intrusion 108 generated on the side surface 107 a provided in the + ZZ ′ direction of the piezoelectric substrate 102 is greatly generated on the lower surface 110 of the piezoelectric substrate 102. Further, the intrusion 108 generated on the side surface 107 b provided in the −ZZ ′ direction is greatly generated on the upper surface 109 of the piezoelectric substrate 102. Such an intrusion 108 occurs due to anisotropic etching due to the crystal axis of the piezoelectric substrate 102. If the piezoelectric vibrating piece is formed with the piezoelectric substrate 102 in which such an intrusion 108 has occurred, the vibration region of the piezoelectric vibrating piece cannot be secured to the maximum, and there is a problem that the vibration characteristics deteriorate.
In recent years, since the piezoelectric vibrating piece has been reduced in size, there is a problem that when the planar shape of the piezoelectric substrate 102 is reduced, the upper surface 109 and the lower surface 110 of the piezoelectric substrate 102 are almost filled with the entry 108.

  Further, the vibration characteristics and the like of the piezoelectric vibrating piece depend on the shape of the piezoelectric substrate 102. That is, when the side surface 107 of the piezoelectric vibrating piece is formed perpendicular to the upper surface 109 (lower surface 110), the vibration characteristics and the like of the piezoelectric vibrating piece are improved. In order to obtain a piezoelectric vibrating piece having such a shape, it is known that the etching time for forming the piezoelectric substrate 102 may be increased. However, since the intrusion 108 is generated by etching, there is a problem that the amount of the intrusion 108 increases as the etching time is increased.

An object of the present invention is to provide a method for manufacturing a piezoelectric wafer that maintains the shape of the piezoelectric substrate even when the piezoelectric wafer is etched to form the piezoelectric substrate, and that the piezoelectric substrate can be easily folded from the piezoelectric wafer body. To do.

In order to achieve the above object, a method for producing a quartz wafer according to the first embodiment of the present invention includes a crystal axis of quartz, an X axis as an electric axis, a Y axis as a mechanical axis, and an optical axis. and Z-axis, the X axis of the orthogonal coordinate system consisting of a rotating shaft of the shaft the Z axis was tilting the a to rotate the ZZ 'axis + Z side of the Z axis to the -Y side of the Y-axis , said shaft the Y-axis was tilting the a to rotate the + Y side of Y-axis to the + Z side of the Z-axis 'as an axis, the ZZ and the X-axis' YY is constituted by a plane parallel to the axis, said YY A crystal wafer manufacturing method for manufacturing a crystal wafer having a plurality of crystal pieces that can be folded from a crystal wafer body, the crystal wafer having a thickness parallel to an axis, and formed by etching. A protective film that forms a protective film on the front and back main surfaces of the quartz substrate according to the shape of the quartz wafer A step of forming, an etching step of removing a region of the quartz substrate that is not covered with the protective film by etching, and a step of removing the protective film from the quartz substrate, the protective film forming step comprising: In the etching step, a first pair of sides of the crystal piece is along the X axis, a second side of the crystal piece is along the ZZ ′ axis, and a pair of support portions extending in parallel from the crystal wafer body are provided. , Connected to the second side and connected to the crystal piece on the side surfaces adjacent to each other of the pair of support portions, over the entire length of the support portion along the YY ′ axis. The first groove is formed, and the side surfaces opposite to the side surfaces adjacent to each other of the pair of support portions of the crystal piece are formed on the same plane as the first pair of sides, respectively. A protective film is formed on the quartz substrate.
The crystal wafer manufacturing method according to the second aspect of the present invention is the crystal wafer manufacturing method according to the first aspect, wherein the protective film forming step is the etching step, and the pair of support portions of the crystal piece is formed. A second groove is formed over the entire length of the support portion along the YY ′ axis on the side of the connection portion with the crystal piece on each side surface opposite to the side surfaces adjacent to each other. The protective film is formed on the quartz substrate.
The crystal wafer manufacturing method according to a third aspect of the present invention is the crystal wafer manufacturing method according to the second embodiment, wherein the length of the second groove in the direction along the ZZ ′ axis is the first length. One groove is shorter than the length in the direction along the ZZ ′ axis.
According to a fourth aspect of the present invention, there is provided a method for manufacturing a crystal wafer, the method for forming an electrode pattern on the front and back main surfaces of the crystal piece in the method for manufacturing a crystal wafer according to any one of the first to third embodiments. It is characterized by providing.
A quartz wafer manufacturing method according to a fifth aspect of the present invention is the quartz wafer manufacturing method according to any one of the first to fourth embodiments, wherein the support portion of the portion where the groove is formed is folded. And a step of separating the crystal piece from the crystal wafer body.
A crystal wafer manufacturing method according to a sixth aspect of the present invention is the crystal wafer manufacturing method according to any one of the first to fifth aspects, wherein the crystal substrate is an AT cut crystal. .
[Application Example 1] The piezoelectric wafer according to Application Example 1 is characterized in that support portions connected to the piezoelectric wafer main body are provided at both ends of the surface provided on the base end side of the piezoelectric substrate. The outer surface of the support portion is provided continuously along the side surface of the piezoelectric substrate. Further, the inner surface of the support portion is provided with a first groove along the surface provided on the base end side of the piezoelectric substrate. The side surface of the piezoelectric substrate intersects the surface provided on the base end side of the piezoelectric substrate.

  Since the outer side surface of the support part and the side surface of the piezoelectric substrate are also continuous, there is no stagnation that causes penetration into the piezoelectric substrate by etching. Therefore, even if the piezoelectric wafer is immersed in the etching solution, the piezoelectric substrate does not enter and the shape of the piezoelectric substrate can be obtained as desired. Even if the etching time is extended or the shape of the piezoelectric substrate is reduced, the piezoelectric substrate does not enter, and the shape of the piezoelectric substrate is maintained even after etching. Can do. Further, since the support portion is provided with the first groove, the first groove becomes a base point when the piezoelectric substrate is separated from the support portion, and the piezoelectric substrate can be easily separated from the piezoelectric wafer body.

Application Example 2 The piezoelectric wafer according to Application Example 2 is the piezoelectric wafer according to Application Example 1, in which the outer surface of the support portion is along the surface provided on the base end side of the piezoelectric substrate. The second groove is provided.
Application Example 3 A piezoelectric wafer according to Application Example 3 is characterized in that in the piezoelectric wafer described in Application Example 2, the length of the second groove is shorter than the length of the first groove.

  Since the second groove having a shorter length than the first groove is provided between the side surface of the piezoelectric substrate and the outer side surface of the support portion, the amount of intrusion generated in the piezoelectric substrate by etching is extremely small. Can be. For this reason, even if the etching time is increased in order to adjust the shape of the piezoelectric substrate, the shape does not deteriorate because the intrusion generated in the piezoelectric substrate is slight, and the shape of the piezoelectric substrate can be maintained. Further, even when the etching time is increased, the piezoelectric substrate does not enter, and the shape of the piezoelectric substrate can be maintained even when the etching is performed. Further, since the first groove and the second groove are provided in the support portion, the first groove and the second groove serve as a base point when the piezoelectric substrate is separated from the support portion, and the piezoelectric wafer main body is separated from the piezoelectric wafer body. The substrate can be easily separated.

Application Example 4 A piezoelectric wafer according to Application Example 4 is characterized in that in the piezoelectric wafer according to any one of Application Examples 1 to 3, the piezoelectric substrate is an AT-cut crystal.
Accordingly, the side surface along the X axis of the piezoelectric substrate does not enter and a piezoelectric substrate having a desired shape can be obtained.

Application Example 5 In the piezoelectric device according to Application Example 5 , an electrode pattern is provided on the piezoelectric substrate provided on the piezoelectric wafer according to any one of Application Examples 1 to 4 , and the piezoelectric substrate is separated from the support portion. It is characterized by.
Since the side surface does not enter the inside of the piezoelectric substrate, if the piezoelectric device is formed using this piezoelectric substrate, the vibration region can be secured to the maximum. In such a piezoelectric device, various characteristics such as vibration characteristics can be improved and stabilization can be achieved.

Application Example 6 A piezoelectric device according to Application Example 6 is characterized in that in the piezoelectric device described in Application Example 5, the piezoelectric substrate provided with the electrode pattern is mounted on a package.
As a result, the piezoelectric device can improve various characteristics such as vibration characteristics and can be stabilized.

It is the top view to which a part of piezoelectric wafer concerning a 1st embodiment was expanded. It is a top view of the piezoelectric substrate in which the electrode pattern was formed. It is explanatory drawing which expanded a part of piezoelectric wafer concerning 2nd Embodiment. It is sectional drawing of a piezoelectric vibrator. It is explanatory drawing which expanded a part of piezoelectric wafer which concerns on a prior art. It is explanatory drawing of the penetration after an etching.

  The best embodiments of the piezoelectric wafer and the piezoelectric device according to the present invention will be described below. First, the first embodiment will be described. FIG. 1 is an enlarged plan view of a part of the piezoelectric wafer according to the first embodiment. FIG. 1 is an enlarged view of one piezoelectric substrate.

  A plurality of piezoelectric substrates 20 are formed on the piezoelectric wafer 10 by etching. Each piezoelectric substrate 20 is connected to the piezoelectric wafer body 12 via a support portion 40. The piezoelectric substrate 20 is connected to the support portion 40 at both ends of the surface (base end surface) 22 provided on the base end 26 side. When an AT-cut quartz crystal is used as the piezoelectric wafer 10, the side surface 24 of the piezoelectric substrate 20 is formed along the X axis and intersects the side surface 24 as shown in FIG. Is formed along the ZZ ′ axis. In FIG. 1, the direction from the base end 26 to the free end 28 of the piezoelectric substrate 20 is the −X direction, and the direction from the lower side to the upper side of the drawing is the + ZZ ′ direction.

  Each support portion 40 is provided with a first groove 44 on a surface (inner surface) 42 where the support portions 40 face each other. The first groove 44 is provided along the base end surface 22 of the piezoelectric substrate 20 and penetrates from the upper surface to the lower surface of the piezoelectric wafer 10. Further, the outer surface (outer surface) 46 of the support portion 40 is provided continuously to the side surface 24 of the piezoelectric substrate 20.

  Next, a method for separating the piezoelectric substrate 20 and a method for manufacturing a piezoelectric vibrating piece (piezoelectric device) will be described. First, protective films (not shown) for the etching solution are formed on the upper and lower surfaces of the piezoelectric wafer 10. The protective film is formed on a portion where these are provided according to the shape of the piezoelectric substrate 20, the support portion 40, and the piezoelectric wafer body 12. When the piezoelectric wafer 10 on which the protective film is formed is immersed in an etching solution, the portion not covered with the protective film is etched, and the upper surface and the lower surface of the piezoelectric wafer 10 penetrate. As a result, a first groove 44 is formed on the inner side surface 42 of the support portion 40. Further, the outer surface 46 of the support portion 40 is formed continuously with the side surface 24 of the piezoelectric substrate 20. For this reason, the piezoelectric substrate 20 does not have an indentation caused by etching, so that no entry occurs from the corner of the base end 26.

  Then, after an elapse of time for removing unnecessary portions of the piezoelectric wafer 10 and penetrating the upper and lower surfaces of the piezoelectric wafer 10, the piezoelectric wafer 10 is taken out of the etching solution. The etching time is appropriately set according to the etching environment such as the concentration and temperature of the etching solution. When the piezoelectric wafer 10 is taken out of the etching solution, the protective film formed on the upper surface and the lower surface is removed. As a result, the piezoelectric substrate 20 connected to the piezoelectric wafer body 12 via the support portion 40 is formed on the piezoelectric wafer 10.

  Thereafter, electrode patterns are formed on the upper and lower surfaces of the piezoelectric substrate 20 formed on the piezoelectric wafer 10. FIG. 2 is a plan view of a piezoelectric substrate on which an electrode pattern is formed. In FIG. 2, the description of the support portion 40 connected to the piezoelectric substrate 20 is omitted. Each electrode pattern 30 includes an excitation electrode 32, a connection electrode 34, and a lead electrode 36. The electrode pattern 30 is formed, for example, by covering the piezoelectric wafer 10 with a jig having an opening corresponding to the shape of the electrode pattern 30 and forming a metal film on the piezoelectric substrate 20 exposed in the opening. It only has to be done. The electrode pattern 30 can also be formed using a photolithography technique. The excitation electrode 32 is provided at the center of the piezoelectric substrate 20. The connection electrodes 34 are provided at both ends of one side of the piezoelectric substrate 20. The extraction electrode 36 connects the excitation electrode 32 and the connection electrode 34 on a one-to-one basis.

  Thereafter, the piezoelectric substrate 20 is separated from the piezoelectric wafer 10. As a specific example of this separation method, the piezoelectric wafer 10 is first mounted on a fixing jig, and the piezoelectric wafer body 12 is held by the fixing jig. Then, a pin is pressed against the piezoelectric substrate 20 from above the piezoelectric substrate 20 to fold the piezoelectric substrate 20. At this time, the first groove 44 provided in the support portion 40 becomes a part of the folding, and the piezoelectric substrate 20 is folded from the portion where the first groove 44 is provided. In addition, since the first groove 44 is provided in the support portion 40 along the base end surface 22 of the piezoelectric substrate 20, even when the piezoelectric substrate 20 is folded, the broken cut surface is the same as that of the piezoelectric substrate 20. Along the base end face 22. Thereby, the piezoelectric substrate 20 is formed, and at the same time, the piezoelectric vibrating piece 38 is formed. Note that the electrode pattern 30 may be formed on the upper surface and the lower surface of the piezoelectric substrate 20 after the piezoelectric substrate 20 is broken from the piezoelectric wafer 10.

  According to the piezoelectric wafer 10 and the piezoelectric vibrating piece 38 as described above, the side surface 24 along the X axis of the piezoelectric substrate 20 and the outer surface 46 of the support portion 40 are continuous. There is no. For this reason, even if the etching time is increased in order to adjust the shape of the piezoelectric substrate 20, the piezoelectric substrate 20 does not enter and the shape of the piezoelectric substrate 20 does not deteriorate. Therefore, the side surface shape of the piezoelectric substrate 20 can be uniformly finished on the outer periphery of the piezoelectric substrate 20.

  Since the side surface does not enter the inside of the piezoelectric substrate 20, the vibration region can be secured to the maximum when the piezoelectric vibrating piece 38 is formed by the piezoelectric substrate 20. Such a piezoelectric vibrating piece 38 can improve various characteristics such as vibration characteristics and can be stabilized.

  Further, since the first groove 44 is provided in the support portion 40 connecting the piezoelectric substrate 20 and the piezoelectric wafer body 12, the piezoelectric substrate 20 can be easily folded from the piezoelectric wafer body 12. Further, the first groove 44 does not necessarily have to penetrate. The piezoelectric wafer 10 may be not only AT-cut quartz but also cut out at other cut angles.

  Next, a second embodiment will be described. In the second embodiment, the same components as those of the piezoelectric wafer and the piezoelectric device described in the first embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted. FIG. 3 is an explanatory diagram enlarging a part of the piezoelectric wafer according to the second embodiment. 3A is an enlarged plan view of one piezoelectric substrate, and FIG. 3B is an enlarged plan view of a circled portion in FIG. 3A.

  A plurality of piezoelectric substrates 20 are formed on the piezoelectric wafer 10 by etching, and both ends of the base end surface 22 of the piezoelectric substrate 20 and the piezoelectric wafer main body 12 are connected by a support unit 40. When AT-cut quartz is used as the piezoelectric wafer 10, the side surface 24 of the piezoelectric substrate 20 is formed along the X axis as shown in FIG. 3, and the surface intersecting the side surface 24 is ZZ. 'It is formed along the axis.

Each support portion 40 is provided with a first groove 44 on the inner side surface 42. The first groove 44 is provided along the base end surface 22 of the piezoelectric substrate 20 and penetrates from the upper surface to the lower surface of the piezoelectric wafer 10. Each support portion 40 is provided with a second groove 48 on the outer surface 46. The second groove 48 is provided along the base end surface 22 of the piezoelectric substrate 20 and penetrates from the upper surface to the lower surface of the piezoelectric wafer 10. The length a of the first groove 44 and the length b of the second groove 48 satisfy the relationship 0 <b <a.
A method for separating the piezoelectric substrate 20 and a method for manufacturing a piezoelectric vibrating piece (piezoelectric device) obtained from the piezoelectric substrate 20 may be the same as those described in the first embodiment.

According to the piezoelectric wafer 10 and the piezoelectric vibrating piece as described above, the second shorter than the first groove 44 between the side surface 24 along the X axis of the piezoelectric substrate 20 and the outer surface 46 of the support portion 40. Since the groove 48 is provided, the amount of intrusion generated by etching can be made extremely small. For this reason, even if the etching time is increased in order to adjust the shape of the piezoelectric substrate 20, the shape does not deteriorate because the penetration that occurs in the piezoelectric substrate 20 is slight. If a piezoelectric vibrating piece is formed with the piezoelectric substrate 20, the vibration region can be secured to the maximum. In addition, the piezoelectric vibrating piece using the piezoelectric substrate 20 can improve various characteristics such as vibration characteristics and can be further stabilized.
Further, since the first groove 44 and the second groove 48 are provided in the support portion 40 that connects the piezoelectric substrate 20 and the piezoelectric wafer body 12, the piezoelectric substrate 20 can be more easily folded from the piezoelectric wafer body 12. Can be taken.

  The planar shape of the second groove 48 is rectangular in FIG. 3, but is not limited to this shape, and may be any shape such as a triangle or a semicircle. The first groove 44 and the second groove 48 do not necessarily have to penetrate. In addition, the piezoelectric wafer 10 may be not only AT-cut quartz but also one cut at another cut angle.

  Next, a third embodiment will be described. In the third embodiment, a piezoelectric vibrator will be described. In the third embodiment, the same reference numerals are given to the same components as those described in the first and second embodiments. FIG. 4 is a cross-sectional view of the piezoelectric vibrator.

  The piezoelectric vibrator 50 (piezoelectric device) has a configuration in which the piezoelectric vibrating piece 38 described in the first and second embodiments is mounted on a package 52. The package 52 includes a package base 54 and a lid 56. External terminals 58 are provided on the back surface of the package base 54. Further, the package base 54 includes a recessed portion 60 that opens upward. A mount electrode 62 is provided on the bottom surface of the recessed portion 60. The mount electrode 62 is electrically connected to the external terminal 58. A piezoelectric vibrating piece 38 is mounted on the mount electrode 62 via a conductive bonding material 64. As a result, the mount electrode 62 and the connection electrode 34 of the piezoelectric vibrating piece 38 are electrically connected via the conductive bonding material 64. A lid 56 is bonded onto the package base 54 on which the piezoelectric vibrating piece 38 is mounted, and the recessed portion 60 is hermetically sealed.

  In such a piezoelectric vibrator 50, since the piezoelectric substrate 20 which does not enter is used, it is possible to prevent various characteristics such as vibration characteristics from deteriorating. Further, even when the piezoelectric vibrator 50 having a reduced planar size is formed by using the miniaturized piezoelectric vibrating piece 38, since no penetration occurs in the piezoelectric substrate 20, a vibration region can be secured. It is possible to prevent various characteristics such as vibration characteristics from deteriorating.

  The package 52 can also be equipped with a circuit that oscillates the piezoelectric vibrating piece 38. The package 52 includes a circuit that oscillates the piezoelectric vibrating piece 38, a temperature compensation circuit that increases the frequency stability with respect to the temperature of the piezoelectric vibrating piece 38, and an output frequency of the piezoelectric vibrating piece 38 that is controlled according to a set voltage. A circuit can also be mounted.

DESCRIPTION OF SYMBOLS 10 ......... Piezoelectric wafer, 12 ......... Piezoelectric wafer main body, 20 ......... Piezoelectric substrate, 22 ......... Base end face, 26 ......... Base end, 30 ...... Electrode pattern, 38 ...... Piezoelectric vibrating piece , 40... Supporting part 42... Inner side surface 44... First groove 46... Outer surface 48 48 Second groove 50.

Claims (6)

A crystal axis of quartz, an X axis as an electrical axis, a Y axis as a mechanical axis, and a Z axis as an optical axis, and the X axis of the orthogonal coordinate system as a rotation axis, + Z of the Z axis axis the Z-axis was tilting the a to rotate the side in the -Y side of the Y-axis and ZZ 'axis, tilting the Y-axis so as to rotate the + Y side of the Y-axis to the + Z side of the Z axis A digit axis is defined as a YY ′ axis, a plane parallel to the X axis and the ZZ ′ axis, and a quartz substrate having a thickness parallel to the YY ′ axis.
A method for manufacturing a crystal wafer, which manufactures a crystal wafer having a plurality of crystal pieces that can be folded from a crystal wafer body,
A protective film forming step of forming a protective film according to the shape of the crystal wafer formed by etching on the front and back main surfaces of the crystal substrate;
An etching step of removing a region of the quartz substrate not covered with the protective film by etching;
Removing the protective film from the quartz substrate;
With
The protective film forming step includes
In the etching step, a first pair of sides of the crystal piece is along the X axis,
The second side of the crystal piece is along the ZZ ′ axis,
A pair of support portions extending in parallel from the crystal wafer body are integrally connected to the second side,
A first groove is formed over the entire length of the thickness of the support portion along the YY ′ axis on the side of the pair of support portions adjacent to each other and the crystal piece .
The side surfaces opposite to the side surfaces adjacent to each other of the pair of support portions of the crystal piece are formed on the same plane as the first pair of sides, respectively.
A method for producing a quartz wafer, comprising forming the protective film on the quartz substrate. The protective film forming step includes
In the etching step,
On the side of the side opposite to the side surfaces adjacent to each other of the pair of support portions of the crystal piece, on the side of the connection portion with the crystal piece, the length of the support portion extends along the YY ′ axis over the entire length of the support portion. So that two grooves are formed,
The method for manufacturing a quartz wafer according to claim 1, wherein the protective film is formed on the quartz substrate. The length of the second groove in the direction along the ZZ ′ axis is
3. The method for manufacturing a quartz wafer according to claim 2 , wherein a length of the first groove in a direction along the ZZ 'axis is shorter. The method for producing a crystal wafer according to any one of claims 1 to 3 , further comprising a step of forming an electrode pattern on the front and back main surfaces of the crystal piece. Crystal according to any one of claims 1 to 4, characterized in that it comprises the step of separating the crystal piece from the quartz wafer body by taking folding the support portion of the portion where the groove is formed Wafer manufacturing method. Method for manufacturing a quartz wafer as claimed in any one of claims 1 to 5, wherein the crystal substrate is a AT-cut crystal.

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