JP6206516B2 - Piezoelectric wafer, method for manufacturing vibrating piece, and method for manufacturing vibrating device - Google Patents

Description

The present invention relates to a piezoelectric wafer, a method for manufacturing a vibrating piece, and a method for manufacturing a vibrating device .

The piezoelectric vibrating piece forms a plurality of piezoelectric vibrating pieces from a single piezoelectric wafer. In the invention described in Patent Document 1, a plurality of crystal pieces are obtained from a crystal substrate such as an AT cut. Specifically, in order to obtain this crystal piece, a metal film is first formed on a crystal substrate, and then a photoresist pattern following the external pattern such as a piezoelectric vibrating piece is provided on the metal film. Then, after etching the metal film using the photoresist pattern as a protective film, the crystal substrate is etched using the photoresist pattern and the metal film pattern as a protective film to form a crystal piece, an arm portion, and a frame portion. The base end side of the crystal piece is in the −X direction, and is fixed to the frame portion via the arm portion. The tip side of the crystal piece is in the + X direction. Thereafter, the photoresist pattern and the metal film are peeled off, and an electrode is formed on the crystal piece to obtain a crystal piece aggregate. Next, the crystal piece is separated into pieces by folding the crystal piece from the arm portion.
The quartz crystal resonator element described in Patent Document 2 is held at one end, and the −X side is a free end and the + X side is a fixed end.

Japanese Patent Laying-Open No. 2006-186847 (page 6, FIGS. 1 and 2) JP 2005-130218 A (paragraph 0023)

  As described above, before the crystal piece described in Patent Document 1 is folded from the frame, the base end side of the crystal piece in the −X direction is fixed to the frame portion, and the + X direction is the front end side. In such a crystal piece, when the outer shape of the crystal piece is formed, the corner portion on the tip side is etched, and a large penetration into the inside of the chip occurs. That is, the tip end side of the crystal piece gradually becomes thinner from the inside to the outside of the chip.

  By the way, in a crystal resonator or the like having a crystal piece mounted on a package, it is necessary to prevent the crystal piece from being bent even when an impact is applied due to dropping or the like. For this reason, a pillow is provided on the bottom surface inside the package so as to support the tip side of the crystal piece to prevent the crystal piece from being bent. However, as described above, when a crystal piece with an intrusion is supported by a “pillow”, the crystal piece is thin and weak against impacts. The piece may be damaged. Therefore, the reliability (impact resistance) of the device on which the crystal piece is mounted is deteriorated.

  An excitation electrode is formed on the main surface of the crystal piece. However, when the penetration becomes large, it reaches the portion where the excitation electrode is formed, and the shape influence is generated on the excitation electrode. Further, when the crystal piece is a mesa shape, the shape effect of the thick mesa portion is generated. Therefore, in these cases, the vibration region of the crystal piece is hindered, and various characteristics of the crystal piece are deteriorated.

Furthermore, although the base end of the crystal piece described in Patent Document 1 is connected to the arm portion, the shape near the support portion is complicated by etching. When such a crystal piece is folded from the arm portion, a large amount of broken scraps are generated, and a large residue (burr) is generated at the time of folding. When a crystal piece with a large residue is mounted on the package, the package comes into contact with the conductive wall surface of the package, causing a problem that the crystal piece does not oscillate.
Patent Document 2 does not describe how to draw an electrode pattern around a crystal piece.

An object of the present invention is to provide a piezoelectric wafer, a method for manufacturing a vibrating piece, and a method for manufacturing a vibrating device that prevent disconnection of an electrode pattern that is electrically connected to an excitation electrode.

  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 The crystal X axis of an orthogonal coordinate system including a crystal X axis as an electrical axis, a crystal Y axis as a mechanical axis, and a crystal Z axis as an optical axis, which is a crystal axis of quartz. As a rotation axis, an axis inclined so that the crystal Z axis rotates in the −Y direction of the crystal Y axis to the + Z side is a crystal ZZ ′ axis, and the crystal Y axis is rotated in the + Z direction of the crystal Z axis. The axis inclined so as to be the crystal YY ′ axis, the crystal X axis and the crystal ZZ ′ axis and the two surfaces that are in a relationship of the front and back are the first main surface and the second main surface, A crystal substrate including a crystal substrate having a thickness along a direction along the crystal YY ′ axis, a base end on the + side end of the crystal X axis, and a front end on the − side; A thin portion disposed around the thick portion and having a smaller thickness along the crystal YY ′ axis than the thick portion, and the front of the thin portion An angle formed between at least one main surface of the first main surface and the second main surface, which is on the base end side, connected to the first main surface and the second main surface; An excitation electrode provided in the thick part, and a first electrode provided on the first main surface on the base end side of the thin part. A pattern, a second electrode pattern provided on the second main surface on the base end side of the thin portion, and the first electrode pattern and the second electrode provided on the entry surface A mount electrode including a third electrode pattern connecting the pattern, a connecting portion extending from the base end in the + direction of the crystal X axis, and the base end and the connecting portion. And having an outer edge that intersects the crystal ZZ ′ axis, the outer edge being the crystal ZZ ′ of the base end Anda notch is located inside the ends in the direction along the, in plan view of the quartz substrate, a piezoelectric wafer, characterized in that the ridge line of the angle between the outer edge is continuous .

Application Example 2 Arranged between the base end and the connecting portion, is continuous with the cutout portion, and is thinner along the crystal YY ′ axis than the base end and the connecting portion. The piezoelectric wafer according to Application Example 1, including a groove provided to be

Application Example 3 The piezoelectric wafer according to Application Example 1 or 2, wherein the quartz substrate is an AT-cut quartz substrate .

[Application Example 4] A step of preparing the piezoelectric wafer according to any one of Application Examples 1 to 3, and a part of the piezoelectric wafer from the base end to the tip end side is folded at the notch to be separated into pieces. And a process for manufacturing the resonator element.

[Application Example 5] A step of preparing the piezoelectric wafer according to any one of Application Examples 1 to 3, and a portion of the piezoelectric wafer from the base end to the tip end side is folded at the notch to be separated into pieces. And a step of preparing a package, and a step of mounting the vibration piece separated in the step of dividing into the package on the package.
Application Example 6 In the step of mounting the resonator element on the package, a conductive adhesive is disposed between the third electrode pattern and an electrode pad provided on the package, and the electrode pad and the electrode 6. The method for manufacturing a vibration device according to Application Example 5, wherein the excitation electrode is electrically connected.

It is explanatory drawing of a piezoelectric vibrating piece. It is the schematic plan view which expanded a part of piezoelectric wafer which formed the mesa type piezoelectric vibrating piece. It is explanatory drawing of the part which the mesa type piezoelectric vibrating piece and the connection part are connected. It is explanatory drawing of a mesa type piezoelectric device.

  Hereinafter, the best embodiments of the piezoelectric vibrating piece, the piezoelectric device, and the method of manufacturing the piezoelectric vibrating piece according to the present invention will be described. In the following, a mode using a mesa-type piezoelectric vibrating piece as an example of the piezoelectric vibrating piece will be described, but the present invention is not limited to this mode. That is, the piezoelectric vibrating piece according to the present invention may have a shape other than the mesa shape, for example, a flat plate shape.

  First, the mesa type piezoelectric vibrating piece will be described. FIG. 1 is an explanatory diagram of a piezoelectric vibrating piece. Here, FIG. 1A is a plan view of a mesa-type piezoelectric vibrating piece, and FIG. 1B is a cross-sectional view taken along the line AA of FIG. The mesa-type piezoelectric vibrating piece 10 has a piezoelectric element plate 12. The piezoelectric element plate 12 has a thick portion 14 and a thin portion 16 formed thinner than the thick portion 14. The thin portion 16 is adjacent to the thick portion 14 and is provided at the center of the thick portion 14 in the height direction. As a specific example of the piezoelectric element plate 12, an AT-cut crystal element plate can be cited. As shown in FIG. 1A, the mesa-type piezoelectric vibrating piece 10 using the AT-cut quartz element plate has a long side along the X axis and a short side along the ZZ ′ axis. The base end 18 side of the mesa-type piezoelectric vibrating piece 10 is the + X side, and the tip 20 side is the −X side.

  For this reason, if the piezoelectric element plate 12 is wet-etched when forming the outer shape pattern thereof, the side surface 12c on the base end 18 side in the long side is etched, and the intrusion 22 is formed. As shown in FIG. 1B, the intrusion 22 is formed on the + ZZ ′ side by etching the upper main surface 12a of the two long sides formed on the −ZZ ′ side. The thing has etched the lower main surface 12b side. The angle formed between the upper main surface 12a and the -ZZ 'side entry 22 is an obtuse angle, and the angle formed between the lower main surface 12b and the + ZZ' side entry 22 is an obtuse angle.

In such a piezoelectric base plate 12, excitation electrodes 30 are provided on the main surface of the thick portion 14. Electrode patterns 32 (mount electrodes 34) are provided at both corners on the base end 18 side of the piezoelectric element plate 12, respectively. The mount electrode 34 is electrically connected to the excitation electrode 30 by a lead electrode 36 (electrode pattern 32). The mount electrode 34 is provided on the upper main surface 12a, the lower main surface 12b, and the side surface 12c of the piezoelectric base plate 12 (thin portion 16). As a result, the mount electrode 34 provided on the upper main surface 12a and the mount electrode 34 provided on the lower main surface 12b are electrically connected via the side surface 12c. The mount electrode 34 is also provided on the surface of the entrance 22. As a result, the mount electrode 34 is less likely to break at a location where the angle formed by the main surfaces 12a, 12b of the piezoelectric base plate 12 (thinned portion 16) and the entry 22 is an obtuse angle.
The mount electrodes 34 provided on the main surfaces 12a and 12c constitute the first and second electrode patterns, and the mount electrodes provided on the side surfaces 12c constitute the third electrode pattern.

  An example of a method for manufacturing the mesa type piezoelectric vibrating piece 10 is as follows. FIG. 2 is an enlarged schematic plan view of a part of the piezoelectric wafer on which the mesa piezoelectric vibrating piece is formed. FIG. 3 is an explanatory diagram of a portion where the mesa-type piezoelectric vibrating piece and the connecting portion are connected. 3A is a plan view, FIG. 3B is a cross-sectional view taken along the broken line BB ′ in FIG. 3A, and FIG. 3C is taken along the broken line CC ′ in FIG. It is sectional drawing.

  First, the piezoelectric base plate 12, that is, the thick portion 14 and the thin portion 16 provided around the thick portion 14 can be formed by processing using photolithography and etching. The specific formation process of the piezoelectric element plate 12 is as follows. First, a mask made of a metal film is formed on the surface of the piezoelectric wafer 40, and then the piezoelectric wafer 40 exposed in the opening of the mask is wet-etched to form a plurality of piezoelectric element plates from the piezoelectric element plate 12 and one piezoelectric wafer 40. 12 are formed, such as a support portion 42 formed to obtain 12, a connection portion 44 that connects the support portion 42 and the piezoelectric element plate 12, and a frame portion 46 that connects the plurality of support portions 42. The support portion 42 and the frame portion 46 serve as a piezoelectric wafer body. If the piezoelectric wafer is an AT-cut quartz wafer, the support portion 42 and the frame portion 46 are the quartz wafer body. Further, if the piezoelectric wafer is an AT-cut quartz wafer, as shown in FIG. 2, the base end 18 side of the piezoelectric base plate 12 is in the + X direction of the crystal crystal axis, and the tip 20 side is in the −X direction. Is along the ZZ ′ axis of the quartz crystal axis.

  Next, in order to form the thick portion 14, a portion corresponding to the portion where the thick portion 14 is formed is covered with a metal film mask, and the opening portion of the mask is wet-etched. As a result, the thin portion 16 is formed on the piezoelectric base plate 12, and when the metal film serving as the mask is removed, the piezoelectric wafer 40 becomes a shape as shown in FIG. The base plate 12 can be obtained. In FIG. 2, descriptions of the thick portion 14, the cutout portion 48, the entry 22, and the like are omitted.

In the obtained piezoelectric wafer 40, a notch portion 48 is provided between the piezoelectric element plate 12 and the connecting portion 44 in order to make it easy to fold the mesa-type piezoelectric vibrating piece 10 from the piezoelectric wafer 40 (FIG. 3). See). As shown in FIG. 3A, the notch 48 is provided at a location where the long side of the piezoelectric element plate 12 and the side along the X axis of the connecting part 44 are connected, and the piezoelectric element plate. 12 is cut out from an upper main surface 12a to a lower main surface 12b. Further, as shown in FIGS. 3B and 3C, a groove 50 is formed between the piezoelectric element plate 12 and the connecting portion 44 along the short side direction of the piezoelectric element plate 12. Is integrally connected to the connecting portion 44 on the lower main surface 12b side. The groove 50 is an intrusion formed by wet etching. For this reason, the connecting portion 44 connected to the base end 18 of the mesa-type piezoelectric vibrating piece 10 is thinner than the piezoelectric wafer body.
Further, as shown in FIG. 3A, an intrusion 22 is formed on the main surface 12 b below the piezoelectric element plate 12. By providing such a notch 48, the mesa piezoelectric vibrating piece 10 can be easily folded from the piezoelectric wafer 40.

After the piezoelectric element plate 12 is formed on the piezoelectric wafer 40, the excitation electrode 30, the mount electrode 34, and the extraction electrode 36 are formed on the surface of the piezoelectric element plate 12. These electrodes 30, 34, and 36 may be obtained by forming a metal film for electrodes having a pattern following the electrode shape on the surface of the piezoelectric element plate 12. In this case, since a metal film for an electrode is also formed on the surface of the entrance 22 of the piezoelectric base plate 12, the electrode pattern 32 at a location where the angle formed by the main surfaces 12a, 12b and the entrance 22 is an obtuse angle. The disconnection is prevented. Thereby, the mesa-type piezoelectric vibrating piece 10 connected to the piezoelectric wafer 40 is formed.
Thereafter, when the mesa-type piezoelectric vibrating piece 10 is folded from the connecting portion 44, the mesa-type piezoelectric vibrating piece 10 separated into pieces is obtained as shown in FIG. Note that the mesa-type piezoelectric vibrating piece 10 is broken off at the intrusion (groove 50) portion formed in the connecting portion 44.

  According to such a mesa type piezoelectric vibrating piece 10, since the electrode pattern 32 is provided also in the intrusion 22 where the angle between the main surfaces 12a and 12b is an obtuse angle, disconnection of the electrode pattern 32 can be prevented.

  Further, since the mesa-type piezoelectric vibrating piece 10 is provided with the mount electrode 34 on the base end 18 side where the intrusion 22 occurs due to etching, the intrusion 22 does not enter the distal end 20 side of the piezoelectric element plate 12. For this reason, since the shape of the tip 20 side can be prevented from being deformed by etching, the shape of the thick portion 14 can also be prevented from being deformed. As a result, the rigidity of the mesa-type piezoelectric vibrating piece 10 can be improved and the shape of the thick portion 14 and the excitation electrode 30 can be prevented from changing. The vibration region can be secured even when the plane size of the piezoelectric element 12 is reduced.

  Further, since the shape of the portion where the mesa-type piezoelectric vibrating piece 10 and the connecting portion 44 are connected (the shape of the portion to be broken at the time of folding) is a simple shape as shown in FIG. 3, the mesa-type piezoelectric vibration The piece 10 can be easily broken off from the connecting portion 44. That is, since the base end 18 side of the piezoelectric element plate 12 is thinned by etching, the cross-sectional area of the portion to be folded can be reduced. As a result, a strong force is applied when folding, and breakage from an unintended place can be prevented. Further, since generation of breakage debris during folding can be prevented, it is possible to prevent breakage debris from being attached to the vibration region, increasing the crystal impedance value and degrading the Q value. Furthermore, since the generation of a residue (burr) at the time of breaking can be prevented, the residue can be prevented from coming into contact with the wall surface when the mesa piezoelectric vibrating piece 10 is mounted on a package.

  Next, a piezoelectric device (mesa type piezoelectric device) on which the above-described mesa type piezoelectric vibrating piece 10 is mounted will be described. FIG. 4 is an explanatory diagram of a mesa piezoelectric device. In FIG. 4, the description of the excitation electrode 30 and the electrode pattern 32 is omitted. The mesa piezoelectric device 60 includes the package 62. The package 62 has a package base 64 and a lid 72. The package base 64 includes a recessed portion 66 that opens upward, and a pair of package-side mount electrodes 68 are provided on the bottom surface of the recessed portion 66. An external terminal 70 is provided on the back surface of the package base 64 and is electrically connected to the package-side mount electrode 68 on a one-to-one basis.

  The package base 64 may have a configuration in which a recess 66 is formed by disposing a frame-type seam ring on the upper surface of a flat insulating sheet. In this case, the package-side mount electrode 68 may be provided on the upper surface of the insulating sheet, and the external terminal 70 may be provided on the lower surface. As a result, the side wall of the package base 64 is formed by a seam ring. Therefore, the lid 72 can be directly joined onto the seam ring, and the package 62 can be made thin.

A conductive adhesive 74 is applied on the package side mount electrode 68, and the mesa piezoelectric vibrating piece 10 is disposed on the conductive adhesive 74. At this time, the conductive adhesive 74 is bonded to the mount electrode 34, and in the mesa-type piezoelectric vibrating piece 10 having the configuration shown in FIG. As a result, the intrusion 22 has an obtuse angle with the upper principal surface 12a of the piezoelectric element 12 (thin portion 16) (an indentation 22 formed on the −ZZ ′ side of the long side of the piezoelectric element 12). Since the conductive adhesive 74 also comes into contact, the package-side mount electrode 68 and the excitation electrode 30 of the mesa-type piezoelectric vibrating piece 10 are reliably conducted one-to-one via the conductive adhesive 74.
Thus, the lid 72 is joined to the upper surface of the package base 64 on which the mesa-type piezoelectric vibrating piece 10 is mounted, and the recessed portion 66 is hermetically sealed.

  According to such a mesa type piezoelectric device 60, the mesa type piezoelectric vibrating piece 10 in which the generation of the etching residue is suppressed is mounted, so that the mesa type piezoelectric vibrating piece 10 and the side wall of the package 62 are in contact with each other. Is preventing. Here, if there is a residue on the mesa-type piezoelectric vibrating piece, the residue may cause the conductive adhesive to come into contact with the wall surface of the recessed portion, resulting in a defective product. Further, if the residue is long, the mesa type piezoelectric vibrating piece cannot be put into the recessed portion. On the other hand, since the mesa piezoelectric vibrating piece 10 according to the present embodiment has no residue, the mesa piezoelectric vibrating piece 10 can be put into the recessed portion 66, and the conductive adhesive 74 and the wall surface of the recessed portion 66 can be used. Can be prevented from contacting and conducting.

  Further, since the mesa-type piezoelectric vibrating piece 10 does not enter the tip 20 side, the penetration 22 does not occur when the mesa-type piezoelectric vibrating piece 10 is cantilever-mounted on the package 62. . For this reason, even if the mesa piezoelectric device 60 falls and has an impact, it is possible to prevent the mesa piezoelectric vibrating piece 10 from being damaged. Therefore, the reliability (impact resistance) of the mesa piezoelectric device 60 can be improved.

  The mesa piezoelectric device 60 is not only in the form of a mesa piezoelectric vibrator as shown in FIG. 4 but also in the form of a mesa piezoelectric oscillator in which an oscillation circuit is housed in a package 62 together with the mesa piezoelectric vibrating piece 10. You can also.

  DESCRIPTION OF SYMBOLS 10 ......... Mesa type piezoelectric vibrating piece, 12 ......... Piezoelectric element plate, 12a ......... Upper main surface, 12b ......... Lower main surface, 12c ......... Side, 14 ......... Thick part, 16 ......... Thin part, 18 ......... Base end, 20 ......... Tip, 22 ...... Intrusion, 30 ......... Excitation electrode, 32 ......... Electrode pattern, 40 ......... Piezoelectric wafer, 42 ... ... support part, 44 ... ... connection part, 48 ... ... notch part, 60 ... ... mesa-type piezoelectric device, 62 ... ... package, 74 ... ... conductive adhesive

Claims (6)

The crystal X axis as an electric axis, the crystal Y axis as a mechanical axis, and the crystal Z axis as an optical axis, which is the crystal axis of quartz, with the crystal X axis in an orthogonal coordinate system as a rotation axis,
An axis tilted so that the crystal Z axis rotates in the −Y direction of the crystal Y axis to the + Z side is a crystal ZZ ′ axis,
The crystal YY 'axis is an axis tilted so that the crystal Y axis rotates in the + Z direction of the crystal Z axis in the + Z direction,
Two surfaces including the crystal X-axis and the crystal ZZ′-axis and having a front-back relationship with each other are defined as a first main surface and a second main surface,
The direction along the crystal YY ′ axis is the thickness,
A crystal substrate having a base on the + side end of the crystal X axis and a tip on the-side end;
The quartz substrate is
The thick part,
A thin portion disposed around the thick portion and having a smaller thickness along the crystal YY ′ axis than the thick portion;
Located on the base end side of the thin portion, connected to the first main surface and the second main surface, and at least one main surface of the first main surface and the second main surface And the angle that the angle made with is an obtuse angle,
Including
An excitation electrode provided in the thick part;
The first electrode pattern provided on the first main surface on the base end side of the thin portion, and provided on the second main surface on the base end side of the thin portion. A mount electrode including a second electrode pattern and a third electrode pattern provided on the intrusion surface and connecting the first electrode pattern and the second electrode pattern;
A connecting portion extending from the base end in the + direction of the crystal X axis;
The outer edge is disposed between the base end and the connecting portion and intersects the crystal ZZ ′ axis, and the outer edge is located inside both ends of the base end in the direction along the crystal ZZ ′ axis. A notched part,
Including
The piezoelectric wafer , wherein the outer edge and the corner ridge line are continuous in a plan view of the quartz substrate. In claim 1,
It is arranged between the base end and the connecting portion, is continuous with the notch, and is provided so that the thickness along the crystal YY ′ axis is thinner than the base end and the connecting portion. A piezoelectric wafer comprising a groove. In claim 1 or 2,
A piezoelectric wafer , wherein the quartz substrate is an AT cut quartz substrate.   Preparing the piezoelectric wafer according to any one of claims 1 to 3,
  A step of breaking the portion of the piezoelectric wafer from the base end to the front end side into pieces by the notch,
A method of manufacturing a resonator element comprising:   Preparing the piezoelectric wafer according to any one of claims 1 to 3,
  A step of breaking the portion of the piezoelectric wafer from the base end to the front end side into pieces by the notch,
  Preparing the package;
  Mounting the vibration piece separated in the individualizing step on the package;
The manufacturing method of the vibration device characterized by including this.   In claim 5,
  In the step of mounting the resonator element on the package,
  A vibrating device, wherein a conductive adhesive is disposed between the third electrode pattern and an electrode pad provided in the package, and the electrode pad and the excitation electrode are electrically connected. Manufacturing method.

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