JP2016039516A - Piezoelectric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric device in which the impact of external electromagnetic waves is prevented, while increase in the crystal impedance (CI) value is prevented.SOLUTION: A piezoelectric device 200 includes a piezoelectric vibration piece 120, a base 140, and a lid 210. The piezoelectric vibration piece includes a vibration part 124 where an excitation electrode 128 is formed, and a frame 122 where a lead electrode 130 is led out from the excitation electrode. The base has one principal surface to which the frame is bonded, and the other principal surface where an earth electrode 141 is formed at one corner. A metal film 212 is formed on the lid so as to cover a region facing a cavity 101. A first castellation 150a formed in the frame and a second castellation 150b formed in a region abutting against one corner of the base overlap in the height direction, the earth electrode and lead electrode do not overlap in the height direction, and the metal film is connected with the earth electrode via the first castellation 150a and second castellation.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a piezoelectric device having a piezoelectric vibrating piece in which a frame portion is formed.

  There is known a piezoelectric device including a piezoelectric vibrating piece having a vibrating portion that vibrates at a predetermined frequency and a frame portion surrounding the vibrating portion, and a base and a lid that sandwich the piezoelectric vibrating piece from both sides. In the piezoelectric vibrating piece, an excitation electrode is formed in the vibration part, and an extraction electrode is drawn from the excitation electrode to the frame part. In such a piezoelectric device, the excitation electrode or the like is affected by electromagnetic waves or the like from the outside of the piezoelectric device, so that noise is generated and the frequency is difficult to stabilize.

  On the other hand, for example, in Patent Document 1, a shield film is formed on the lid so that the excitation electrode formed on the vibrating portion is not affected by electromagnetic waves from the outside, and the shield film is electrically formed on the side surface of the piezoelectric device. It is shown that a shielded external electrode is formed.

Japanese Patent Laid-Open No. 9-289433

  However, in recent years, in order to meet the demand for miniaturization of piezoelectric devices, a plurality of piezoelectric devices may be formed on a wafer, and individual piezoelectric devices may be formed by cutting the wafer. In such a manufacturing method, an electrode cannot be directly formed on the side surface of the piezoelectric device, and therefore the piezoelectric device described in Patent Document 1 cannot be formed by such a manufacturing method.

  In addition, when an electrode is formed on the side surface of a piezoelectric device in the case of using a manufacturing method for forming a plurality of piezoelectric devices on a wafer, castellation is applied to the side surface of the piezoelectric device with the piezoelectric device formed on the wafer. Forming electrodes on the castellations. However, when a castellation is formed on the frame portion of the piezoelectric vibrating piece, the castellation hinders the wiring of the extraction electrode, and the electrical resistance value of the extraction electrode increases to increase the crystal impedance (CI) value. there were. Further, when forming a piezoelectric device on a wafer, it is necessary to form it so as not to affect the adjacent piezoelectric device.

  An object of the present invention is to provide a piezoelectric device that prevents the influence of electromagnetic waves from the outside and prevents an increase in crystal impedance (CI) value.

  The piezoelectric device according to the first aspect includes a piezoelectric vibrating piece, a base, and a lid. The piezoelectric vibrating piece includes a vibrating part that vibrates at a predetermined frequency, a frame part that is separated from the vibrating part and surrounds the vibrating part, and a connecting part that connects the vibrating part and the frame part. Excitation electrodes are formed on each of the electrodes, and extraction electrodes are drawn out from the respective excitation electrodes to the frame portion via connecting portions. A first castellation that is recessed from the outer periphery to the inside is formed on the outer periphery of the frame portion. The base is formed in a rectangular shape including a long side and a short side, a frame portion is joined to one main surface, and a ground electrode is formed at one corner of the other main surface. The lid is joined to the frame portion to form a cavity together with the base, thereby sealing the vibrating portion in the cavity. In addition, a second castellation is formed in a region corresponding to one corner of the base so as to be recessed from the outer periphery of the base, and a metal film is formed on the lid so as to cover a region facing the cavity, and the first caster and the second caster are formed. The metal electrode is connected to the ground electrode via the first castellation and the second castellation, and the ground electrode and the extraction electrode do not overlap in the height direction.

  The piezoelectric device according to the second aspect includes a piezoelectric vibrating piece, a base, and a lid. The piezoelectric vibrating piece includes a vibrating part that vibrates at a predetermined frequency, a frame part that is separated from the vibrating part and surrounds the vibrating part, and a connecting part that connects the vibrating part and the frame part. Excitation electrodes are formed on each of the electrodes, and extraction electrodes are drawn out from the respective excitation electrodes to the frame portion via connecting portions. A first castellation that is recessed from the outer periphery to the inside is formed on the outer periphery of the frame portion. The base is formed in a rectangular shape including a long side and a short side, a frame portion is joined to one main surface, and a ground electrode is formed at one corner of the other main surface. The lid is joined to the frame portion to form a cavity together with the base, thereby sealing the vibrating portion in the cavity. A second castellation is formed in the area corresponding to one corner of the base so as to be recessed from the outer periphery of the base, and the lid has a third castellation recessed from the outer periphery of the lid and a surface opposite to the surface facing the cavity. A metal film is formed so as to cover, the first castellation, the second castellation, and the third castellation overlap in the height direction, the ground electrode and the extraction electrode do not overlap in the height direction, and the metal film is The first castellation, the second castellation, and the third castellation are connected to the ground electrode.

  In the piezoelectric device according to the third aspect, in the first and second aspects, the first castellation is formed at the corner of the base.

  In the piezoelectric device according to the fourth aspect, in the first aspect and the second aspect, the first castellation is formed along the short side of the base.

  In the piezoelectric device according to the fifth aspect, in the first and second aspects, the first castellation is formed on a part of the long side of the base.

  In the piezoelectric device of the sixth aspect, in the first aspect and the second aspect, the metal film and the ground electrode are connected by the side electrode made of the same material as the ground electrode.

  In the piezoelectric device of the seventh aspect, in the first and second aspects, the connection between the metal film and the ground electrode is made by a side electrode made of the same material as the metal film.

  In the piezoelectric device of the eighth aspect, in the first and second aspects, the metal film and the ground electrode are connected by a side electrode made of the same material as the metal film, and the side electrode is electrically connected to the ground electrode. Is connected to the ground electrode with the minimum necessary area that can be secured, and the ground electrode surface is exposed and connected, and the material of the metal film and the side electrode is chromium, tungsten, or molybdenum.

  According to the piezoelectric device of the present invention, it is possible to prevent the influence of electromagnetic waves from the outside and to prevent the crystal impedance (CI) value from increasing.

1 is an exploded perspective view of a piezoelectric device 100. FIG. It is AA sectional drawing of FIG. FIG. 3A is an enlarged view of a dotted line 180 in FIG. FIG. 2B is an enlarged view of a dotted line 181 in FIG. (C) is explanatory drawing of a modification, and is a figure in the same position as FIG.3 (b). FIG. 4A is a top view of the piezoelectric vibrating piece 120. FIG. FIG. 4B is a bottom view of the piezoelectric vibrating piece 120. (A) is a bottom view of the base 140. FIG. 4B is a top view of the lid 110. FIG. 3 is a flowchart illustrating a method for manufacturing the piezoelectric device 100. (A) is a bottom view of the piezoelectric wafer W120. FIG. 7B is an enlarged view of a dotted line 182 in FIG. (A) is a top view of the base wafer W140. (B) is a top view of the lid wafer W110. 2 is an exploded perspective view of a piezoelectric device 200. FIG. (A) is BB sectional drawing of FIG. (B) is explanatory drawing of a modification, and is a figure in the same position as Fig.10 (a). FIG. 4A is an exploded perspective view of the piezoelectric device 300. FIG. FIG. 4B is an exploded perspective view of the piezoelectric device 400. FIG. FIG. 4A is an exploded perspective view of the piezoelectric device 500. FIG. FIG. 4B is an exploded perspective view of the piezoelectric device 600. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the scope of the present invention is not limited to these forms unless otherwise specified in the following description.

(First embodiment)
<Configuration of Piezoelectric Device 100>
FIG. 1 is an exploded perspective view of the piezoelectric device 100. The piezoelectric device 100 has a configuration in which a base 140, a piezoelectric vibrating piece 120, and a lid 110 are stacked. As the piezoelectric vibrating piece 120, for example, an AT-cut crystal vibrating piece is used. The AT-cut quartz crystal resonator element has a main surface (XZ plane) inclined at 35 degrees 15 minutes from the Z axis in the Y axis direction around the X axis of the crystal axis (XYZ). In the following description, the new axes tilted with respect to the axial direction of the AT-cut quartz crystal vibrating piece are used as the Y ′ axis and the Z ′ axis. That is, in the piezoelectric device 100, the longitudinal direction of the piezoelectric device 100 is defined as the X-axis direction, the height direction of the piezoelectric device 100 is defined as the Y′-axis direction, and the direction perpendicular to the X-axis direction and the Y′-axis direction is described as the Z′-axis direction. To do.

  The piezoelectric vibrating piece 120 includes a rectangular vibrating portion 124 that vibrates at a predetermined frequency, and a frame portion 122 that is spaced apart from the vibrating portion 124 and surrounds the vibrating portion 124 is provided outside the vibrating portion 124. The vibrating portion 124 and the frame portion 122 are connected to each other by a connecting portion 126 that extends in the −X axis direction from the −X axis side of the vibrating portion 124 and reaches the frame portion 122. Further, a first castellation 150 a is formed at the corner on the + Z-axis side on the + X-axis side on the outer peripheral side of the frame portion 122 so as to be recessed inward from the outer periphery of the frame portion 122. A first side electrode 152a is formed on the side surface of the first castellation 150a.

  As shown in FIG. 1, excitation electrodes 128 are formed on the surface on the + Y′-axis side and the surface on the −Y′-axis side, which are both main surfaces of the vibration unit 124. In addition, from each excitation electrode 128, an extraction electrode 130 is drawn out to the frame portion 122 via the connecting portion 126. The extraction electrode 130 includes an extraction electrode 130a extracted from the excitation electrode 128 formed on the surface on the + Y ′ axis side, an extraction electrode 130b extracted from the excitation electrode 128 formed on the surface on the −Y ′ axis side, Is included.

  The base 140 is formed in a flat plate shape and joined to the surface of the frame portion 122 on the −Y′-axis side. The base 140 is formed using glass, quartz, or the like as a base material, and is disposed so as to face the vibration unit 124. In addition, a notch 148a formed so that a corner of the base 140 is cut off is formed at a corner of the base 140 on the −X axis side on the −X axis side, and a corner on the −Z ′ axis side of the + X axis side is formed. A notch 148b is formed. Further, a second castellation 150 b is formed at a corner of the base 140 on the + Z-axis side on the + X-axis side so as to be recessed inward from the outer periphery of the base 140. A second side electrode 152b is formed on the side surface of the second castellation 150b. Although various electrodes are formed on the base 140, only the second side electrode 152b is shown in FIG.

  The lid 110 is formed in a flat plate shape and is joined to the surface on the + Y′-axis side of the frame portion 122. The lid 110 is made of glass, quartz, or the like, and is disposed so as to face the vibration unit 124. A metal film 112 is formed on the entire surface of the lid 110 on the + Y′-axis side. A third castellation 150c is formed to be recessed inward from the outer periphery of the lid 110 at the corner on the + Z-axis side of the lid 110 on the + X-axis side, and a third side electrode 152c is formed on the side surface of the third castellation 150c. Is done.

  FIG. 2 is a cross-sectional view taken along the line AA of FIG. Moreover, FIG. 2 includes the AA cross section of FIG. 4A, FIG. 4B, FIG. 5A, and FIG. The lid 110 and the frame portion 122 are bonded together by a non-conductive bonding material 160 such as a resin adhesive such as polyimide or low melting point glass. Further, the base 140 and the frame portion 122 are also joined by the joining material 160. In this way, the vibrating part 124 is hermetically sealed in the cavity 101 surrounded by the lid 110, the frame part 122, and the base 140. The vibrating portion 124 is formed thinner than the frame portion 122 in order to adjust the frequency of the piezoelectric device 100 and so that the vibrating portion 124 does not contact the lid 110 and the base 140.

  A connection terminal 145 for mounting on a printed circuit board or the like is formed on the surface of the base 140 on the −Y′-axis side. The connection terminal 145 includes a ground electrode 141, a mounting electrode 142, and the like. The ground electrode 141 is an electrode to be grounded, and the mounting electrode 142 is an electrode for operating the piezoelectric device 100 as a circuit by being connected to an electrode such as a printed board. In addition, a notch electrode 144 is formed on each side surface of the notch 148a and the notch 148b. Each notch electrode 144 is electrically connected to the extraction electrode 130 and the mounting electrode 142. As a result, the mounting electrode 142 is electrically connected to the excitation electrode 128 through the notch electrode 144 and the extraction electrode 130. The first side electrode 152a formed on the first castellation 150a, the second side electrode 152b formed on the second castellation 150b, and the third side electrode 152c formed on the third castellation 150c are electrically connected to each other. Connected. Thereby, the ground electrode 141 is electrically connected to the metal film 112 formed on the surface at the + Y′-axis side of the lid 110 via the first side electrode 152a, the second side electrode 152b, and the third side electrode 152c. Is done.

  In the piezoelectric device 100, as shown in FIG. 2, the grounded metal film 112 is formed so as to cover the cavity 101 from the + Y′-axis side, thereby preventing electromagnetic waves from the + Y′-axis side with respect to the excitation electrode 128. Therefore, the generation of noise is prevented and a stable frequency output can be obtained. The metal film 112 may be formed only in a region overlapping the excitation electrode 128 in the + Y′-axis direction or only in a region overlapping the cavity 101 in the + Y′-axis direction. In the piezoelectric device 100, the metal film 112 is preferably formed on the entire surface of the lid 110 on the + Y′-axis side, so that the extraction electrode 130 can also be prevented from electromagnetic waves from the + Y′-axis side.

  FIG. 3A is an enlarged view of a dotted line 180 in FIG. The extraction electrode 130 formed on the piezoelectric vibrating piece 120 includes, for example, a chromium (Cr) layer formed on the lowermost layer, a nickel tungsten (NiW) layer formed on the surface of the chromium (Cr) layer, and nickel tungsten (NiW). ) Three layers of gold (Au) layer formed on the surface of the layer. Each of these layers is formed by sputtering or vapor deposition. The excitation electrode 128 is also formed with the same configuration as the extraction electrode 130. Further, the metal film 112 formed on the lid 110 is formed only of, for example, a chromium (Cr) layer. Furthermore, the connection terminal 145 and the notch electrode 144 formed on the base 140 are formed on the surface of the first film 192A and the first film 192A formed by sputtering or vapor deposition, and the second formed by plating. And a film 192B. For example, the first film 192A is formed on the surface of the chromium (Cr) layer formed on the lowermost layer, the nickel tungsten (NiW) layer formed on the surface of the chromium (Cr) layer, and the surface of the nickel tungsten gusten (NiW) layer. It is constituted by a gold (Au) layer. The second film 192B is formed of, for example, a nickel (Ni) layer formed on the surface of the first film 192A and a gold (Au) layer formed on the surface of the nickel (Ni) layer. The material forming the metal film 112 may be other material such as Ni (nickel), Ti (titanium), NiW (nickel tungsten), or Mo (molybdenum) instead of the above-described chromium.

  FIG. 3B is an enlarged view of a dotted line 181 in FIG. The ground electrode 141, the first side electrode 152a, and the second side electrode 152b are formed by the first film 192A and the second film 192B. In addition, the third side surface electrode 152c has the metal film 112 formed on the lowermost layer, and the first film 192A and the second film 192B are formed on the surface of the metal film 112.

  In the piezoelectric device 100 described above, the metal film 112 and the ground electrode 141 are connected by the first film 192A and the second film 192B. Instead, the following configuration may be used. FIG. 3C is an explanatory diagram of the piezoelectric device 195 according to a modified example cut at the same position as in FIG. 3B. In this piezoelectric device 195, the ground electrode 141 is composed of the first films 192A and 192B. On the other hand, the side electrode 197 for connecting the ground electrode 141 and the metal film 112 is made of a chromium film. However, the side electrode 197 is connected to the ground electrode 141 with a necessary minimum area that can ensure electrical connection with the ground electrode 141. That is, as shown in FIG. 3C, on the premise that electrical connection with the ground electrode 141 can be ensured, the side electrode 197 is connected to the ground electrode so that the surface of the ground electrode 141 can be exposed in as wide a region P as possible. 141 is connected. In the piezoelectric device 195 of this modification, since the ground electrode 141 has the region P that exposes the first film 192A and the second film 192B, solder wettability at the time of board mounting can be ensured in this region P. Further, since the side electrode 197 is made of a chromium film, it is possible to prevent the solder from creeping up to the side electrode 197 during mounting on the substrate. Further, since the side electrode 197 is composed of a single layer of chromium film, an effect that the film can be easily formed and an inexpensive material can be obtained. The constituent material of the side electrode 197 is not limited to chromium, but may be any material having relatively poor solder wettability, such as tungsten or molybdenum.

  FIG. 4A is a top view of the piezoelectric vibrating piece 120. In the piezoelectric vibrating piece 120, a through groove 132 that penetrates the piezoelectric vibrating piece 120 in the Y′-axis direction is formed between the vibrating portion 124 and the frame portion 122. In addition, the vibration part 124 and the frame part 122 are connected via a connecting part 126. An excitation electrode 128 is formed on the vibrating portion 124, and an extraction electrode 130 a is drawn from the excitation electrode 128 formed on the surface on the + Y′-axis side to the frame portion 122 via the connecting portion 126. The extraction electrode 130 a is extracted to the surface on the −Y′-axis side of the frame portion 122 through the side surface 134 of the through groove 132. The first castellation 150a is formed at the + Z′-axis side corner of the frame portion 122 on the + X-axis side, and the first side electrode 152a is formed on the first castellation 150a.

  FIG. 4B is a bottom view of the piezoelectric vibrating piece 120. An extraction electrode 130 b is extracted from the excitation electrode 128 formed on the surface at the −Y′-axis side of the vibration unit 124. The extraction electrode 130 b extends from the excitation electrode 128 in the −X-axis direction, passes through the −X-axis side and the −Z′-axis side portions of the frame portion 122, and is a surface on the −Y′-axis side of the frame portion 122. Thus, it extends to the corner on the −Z ′ axis side and the + X axis side. In addition, the extraction electrode 130 a extracted from the excitation electrode 128 formed on the surface at the + Y′-axis side of the vibrating portion 124 is + Z ′ on the surface at the −Y′-axis side of the frame portion 122 through the side surface 134 of the through groove 132. It extends to the corner on the axis side and on the −X axis side. These extraction electrodes 130 a and 130 b are formed to fill the entire width of the surface of the frame portion 122 on the −Y′-axis side. As a result, the extraction electrode can be wired while preventing an increase in the electrical resistance of the extraction electrode, and an increase in the crystal impedance (CI) value can be suppressed.

  On the other hand, the piezoelectric vibrating piece 120 is bonded to the lid 110 and the base 140 by the frame portion 122, but when the width of the frame portion 122 is narrowed, the bonding strength between the piezoelectric vibrating piece 120, the lid 110 and the base 140 is weakened. . Therefore, in order to increase the impact resistance of the piezoelectric device 100, it is necessary to form the frame portion 122 with a wide width. Further, as shown in FIG. 2, the first side electrode 152 a formed on the piezoelectric vibrating piece 120 electrically connects the metal film 112 and the earth electrode 114, but the piezoelectric device 100 like the extraction electrode 130. Therefore, even if the electric resistance is somewhat high, it is not a big problem. That is, the width of the first side electrode 152a may be narrow, and the size of the first castellation 150a may be small. In the piezoelectric device 100, the first castellation 150a is formed in a corner portion where the width of the frame portion 122 is difficult to be narrowed, and the size thereof is further reduced, so that the impact resistance of the piezoelectric device 100 is greatly reduced. Instead, the first side electrode 152a is formed.

  FIG. 5A is a bottom view of the base 140. Four electrodes forming the connection terminal 145 are formed on the surface of the base 140 on the −Y′-axis side. The base 140 is formed in a substantially rectangular shape and has four corners, and the four electrodes constituting the connection terminal 145 are formed at the four corners. Mounting electrodes 142 are respectively formed at a corner on the −Z ′ axis side on the + X axis side and a corner on the + Z ′ axis side on the −X axis side of the surface on the −Y ′ axis side of the base 140. Each mounting electrode 142 is electrically connected to the notch electrode 144. In addition, a ground electrode 141 is formed at a corner on the + Z-axis side on the + X-axis side of the surface on the −Y′-axis side of the base 140. The ground electrode 141 is electrically connected to the second side electrode 152b. Further, an electrode 143 is formed at a corner on the −Z ′ axis side on the −X axis side of the surface on the −Y ′ axis side of the base 140. In the base 140, the electrode 143 is an unused electrode, but may be connected to the ground electrode 141 and used as a part of the ground electrode 141.

  The first castellation 150 a formed on the piezoelectric vibrating piece 120 is arranged in the Y′-axis direction on the second castellation 150 b formed at the corner on the ground electrode 141 side so that the first side electrode 152 a is easily connected to the ground electrode 141. In the base 140, the ground electrode 141 is mainly formed in a region that does not overlap with the extraction electrode 130 (see FIG. 4B) in the Y′-axis direction, so that the extraction electrode 130 is not obstructed. Thus, the first castellation 150a can be formed.

  FIG. 5B is a top view of the lid 110. A metal film 112 is formed on one surface of the lid 110 on the + Y′-axis side. The third castellation 150c is formed at the + Z′-axis side corner of the lid 110 on the + X-axis side, and the third metal film 152c is formed on the third castellation 150c. The metal film 112 and the third metal film 152c are electrically connected. In the piezoelectric device 100, as shown in FIG. 5 (b), the metal film 112 is formed on the entire surface of the lid 110 on the + Y′-axis side, so that the excitation electrode 128 and the extraction electrode 130 are externally connected. It is protected from electromagnetic waves. Thereby, generation | occurrence | production of noise can be prevented and the stable frequency output can be obtained.

  In the piezoelectric vibrating piece 120, the base 140, and the lid 110 shown in FIGS. 4A, 4B, 5A, and 5B, the first castellation 150a, the second castellation 150b, and the third The castellation 150c is formed by a C surface that is cut off in a straight line, but may be formed by an R surface that is cut off in a curved shape.

<Method for Manufacturing Piezoelectric Device 100>
FIG. 6 is a flowchart showing a method for manufacturing the piezoelectric device 100. Below, the manufacturing method of the piezoelectric device 100 is demonstrated with reference to the flowchart of FIG.

  In step S101, a piezoelectric wafer W120 is prepared. Step S101 is a process of preparing a piezoelectric wafer. In step S101, first, a bare wafer formed of a piezoelectric material is prepared. Since the piezoelectric device 100 uses quartz as the piezoelectric material, the prepared bare wafer is a quartz bare wafer. Next, the thickness of the vibration part 124 is adjusted by etching the bare wafer, and the through groove 132 and the first castellation 150a are formed. Further, by forming the excitation electrode 128 and the extraction electrode 130, a plurality of piezoelectric vibrating pieces 120 are formed on the piezoelectric wafer W120.

  FIG. 7A is a bottom view of the piezoelectric wafer W120. FIG. 7A shows a surface at the −Y′-axis side of the piezoelectric wafer W <b> 120. A plurality of piezoelectric vibrating pieces 120 are formed on the piezoelectric wafer W120, and a scribe line 171 is shown at the boundary between the piezoelectric vibrating pieces 120 adjacent to each other. The scribe line 171 indicates a portion where the wafer is cut in step S107 described later. Each piezoelectric vibrating piece 120 is formed with a through groove 132 and a first castellation 150a, and further, an excitation electrode 128 and an extraction electrode 130 are formed. In step S101, the first side electrode 152a is not formed.

  FIG. 7B is an enlarged view of a dotted line 182 in FIG. The first castellation 150a formed on the piezoelectric vibrating piece 120 does not need to be formed large, but the first castellation 150a is formed by etching through the piezoelectric wafer W120, and the first side electrode 152a is formed on the side surface. In order to achieve this, it is necessary to form an area for forming the first castellation 150a on the piezoelectric wafer W120 to a certain size. In the piezoelectric wafer W120, by forming a part of the first castellation 150a on the scribe line 171 formed with a predetermined width, the size of the first castellation 150a formed on each piezoelectric vibrating piece 120 is small. In this state, a necessary size for forming the first side electrode 152a can be ensured.

  Returning to FIG. 6, in step S102, a base wafer W140 is prepared. A plurality of bases 140 are formed on the base wafer W140. In step S102, first, a bare wafer formed of a piezoelectric material or the like is prepared. Next, this bare wafer is etched to form the notches 148a and 148b and the second castellation 150b. Step S102 is a process of preparing the base wafer W140.

  FIG. 8A is a plan view of the base wafer W140. A plurality of bases 140 are formed on the base wafer W140, and a scribe line 171 is shown at the boundary between the bases 140 adjacent to each other. Base wafer W140 is formed of a piezoelectric material such as quartz or glass. In the base wafer W140, as in the piezoelectric wafer W120 shown in FIG. 7B, the second castellation 150b is formed on a part of the scribe line 171.

  In step S103, a lid wafer W110 is prepared. A plurality of lids 110 are formed on the lid wafer W110. In step S102, first, a bare wafer formed of a piezoelectric material or glass is prepared. Next, this bare wafer is etched to form a third castellation 150c. Further, the metal film 112 is formed on the surface of the bare wafer on the + Y′-axis side and the side surface of the third castellation 150c. Step S103 is a process of preparing the lid wafer W110.

  FIG. 8B is a plan view of the lid wafer W110. A plurality of lids 110 are formed on the lid wafer W110, and a scribe line 171 is shown at the boundary between the lids 110 adjacent to each other. A third castellation 150c is formed at the corner of each base 120 on the + Z-axis side on the + X-axis side. A metal film 112 is formed on the surface at the + Y′-axis side of the lid wafer W110 and the side surface of the third castellation 150c. Also in the lid wafer W110, the third castellation 150c is formed in a part of the scribe line 171 as in the piezoelectric wafer W120 shown in FIG.

  In step S104, the piezoelectric wafer W120 and the base wafer W140 are bonded by the bonding material 150. Step S104 is a bonding process between the piezoelectric wafer W120 and the base wafer W140. In step S104, the −Y′-axis side surface of the piezoelectric wafer W120 and the + Y′-axis side surface of the base wafer W140 are bonded to each other via the bonding material 150 so that the scribe lines 171 overlap each other.

  In step S105, the piezoelectric wafer W120 and the lid wafer W110 are bonded by the bonding material 151. Step S105 is a bonding process between the piezoelectric wafer W120 and the lid wafer W110. In step S105, the surface on the + Y′-axis side of the piezoelectric wafer W120 and the surface on the −Y′-axis side of the lid wafer W110 are bonded to each other via the bonding material 151 so that the scribe lines 171 overlap each other. By steps S104 and S105, stacked wafers are formed.

  In step S106, the connection terminal 145, the notch electrode 144, and the first side electrode 152a to the third side electrode 152c are formed. A chromium (Cr) layer, a nickel tungsten (NiW) layer, and a gold (Au) layer are sequentially formed from the surface on the base wafer W140 side, which is the surface on the −Y ′ axis side of the laminated wafer, by sputtering or vapor deposition. As a result, a first film 192A is formed, and a second film 192B is formed by forming a nickel (Ni) film and a gold (Au) film by electroless plating (FIG. 5A, FIG. 5). (See (b)). Thereby, the connection terminal 145, the notch electrode 144, and the first side electrode 152a to the third side electrode 152c are formed.

  In step S107, the stacked wafers are cut by dicing. Step S107 is a cutting process. The laminated wafers are diced along the scribe lines 171 to form the piezoelectric devices 100 as individual pieces.

(Second Embodiment)
As a second embodiment, a modified example of a piezoelectric device in which a metal film or castellation is formed at a position and shape different from those of the first embodiment will be described below. In the following description, the same parts as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description thereof is omitted.

<Configuration of Piezoelectric Device 200>
FIG. 9 is an exploded perspective view of the piezoelectric device 200. The piezoelectric device 200 is formed by laminating a base 140, a piezoelectric vibrating piece 120, and a lid 210. Unlike the lid 110, the lid 210 is not formed with the third castellation, and the metal film 212 is formed on the surface at the −Y′-axis side.

  Fig.10 (a) is BB sectional drawing of FIG. In the piezoelectric device 200, a part of the metal film 212 formed on the lid 210 is exposed to the first castellation 150a and the second castellation 150b. The metal film 212 and the ground electrode 141 are formed by forming the first film 192A and the second film 192B on the metal film 212 exposed when the first side electrode 152a and the second side electrode 152b are formed. Are electrically connected to each other.

  In the piezoelectric device 200 described above, the metal film 212 and the ground electrode 141 are connected by the first film 192A and the second film 192B. Instead, the following configuration may be employed. FIG. 10B is an explanatory view of the piezoelectric device 250 according to a modification, which is a cross-sectional view taken at the same position as in FIG. In this piezoelectric device 250, the ground electrode 141 is composed of the first films 192A and 192B. On the other hand, the side electrode 251 for connecting the ground electrode 141 and the metal film 212 is made of a chromium film. However, the side electrode 251 is connected to the ground electrode 141 with a necessary minimum area that can ensure electrical connection with the ground electrode 141. That is, as shown in FIG. 10B, on the premise that electrical connection with the ground electrode 141 can be secured, the side electrode 251 is connected to the ground electrode so that the surface of the ground electrode 141 can be exposed in as wide a region P as possible. 141 is connected. In the piezoelectric device 250 of this modification, since the ground electrode 141 has the region P that exposes the first film 192A and the second film 192B, solder wettability at the time of board mounting can be ensured in this region P. Further, since the side electrode 197 is made of a chromium film, it is possible to prevent the solder from creeping up to the side electrode 251 when the board is mounted. In addition, since the side electrode 251 is composed of a single layer of chromium film, the effect that the film can be easily formed and an inexpensive material can be obtained. The constituent material of the side electrode 251 is not limited to chromium, but may be any material having relatively poor solder wettability, such as tungsten or molybdenum.

  In the piezoelectric device 200, as shown in FIG. 10, the metal film 212 formed on the lid 210 is formed so as to cover the cavity 101 from the + Y′-axis side, so that the excitation electrode 128 from the + Y′-axis side is formed. Electromagnetic waves are prevented, noise is prevented, and stable frequency output can be obtained. In the piezoelectric device 200, since it is not necessary to form the third castellation on the lid 210, it is easy to form the lid 210, and the number of manufacturing steps can be reduced.

<Configuration of Piezoelectric Device 300>
FIG. 11A is an exploded perspective view of the piezoelectric device 300. FIG. The piezoelectric device 300 is formed by stacking the piezoelectric vibrating piece 320, the base 340, and the lid 310. A metal film 112 is formed on the surface of the lid 310 on the + Y′-axis side, whereby electromagnetic waves from the + Y′-axis side with respect to the excitation electrode 128 are prevented, noise generation is prevented, and a stable frequency output is obtained. be able to. The piezoelectric vibrating piece 320, the base 340, and the lid 310 are different from the piezoelectric device 100 in the shapes of the first castellation, the second castellation, and the third castellation, and the other portions are the same as the piezoelectric device 100. It is.

  A first castellation 350a is formed along the short side on the + Z′-axis side of the piezoelectric vibrating piece 320 on the + X-axis side, and a second caster is formed along the short-side on the + Z′-axis side of the base 320 on the + X-axis side. 350b, and a third castellation 350c extending along the short side is formed on the + Z′-axis side of the lid 310 on the + X-axis side. The first castellation 350a, the second castellation 350b, and the third castellation 350c are arranged to overlap each other in the Y′-axis direction. A first side electrode 352a and a second side electrode 352b formed by the first film 192A and the second film 192B are formed in the first castellation 350a and the second castellation 350b. In addition, a third side electrode 352c formed by the metal film 312, the first film 192A, and the second film 192B is formed in the third castellation 350c.

  In the piezoelectric device 300, the third castellation 350c is formed widely from the first castellation 350a by forming the first castellation 350a to the third castellation 350c along the short side. Therefore, it becomes easy to perform etching, and it is easy to form the third castellation 350c from the first castellation 350a.

<Configuration of Piezoelectric Device 400>
FIG. 11B is an exploded perspective view of the piezoelectric device 400. The piezoelectric device 400 is formed by stacking the piezoelectric vibrating piece 320, the base 340, and the lid 210. The piezoelectric device 400 is formed by using the lid 210 in the piezoelectric device 300 instead of using the lid 310.

  In the piezoelectric device 400, since the lid 210 can be easily formed as in the piezoelectric device 200, the number of manufacturing steps can be reduced. Moreover, since the first castellation 350a and the second castellation 350b are formed widely as in the piezoelectric device 300, it is easy to form the first castellation 350a and the second castellation 350b by etching.

<Configuration of Piezoelectric Device 500>
FIG. 12A is an exploded perspective view of the piezoelectric device 500. The piezoelectric device 500 is formed by stacking a piezoelectric vibrating piece 520, a base 540, and a lid 510. The piezoelectric device 500 differs from the piezoelectric device 100 in that the first castellation 550a, the second castellation 550b, and the third castellation 550c are formed on the piezoelectric vibrating piece 320, the base 340, and the lid 510. The other parts are the same as those of the piezoelectric device 100.

  The first castellation 550a, the second castellation 550b, and the third castellation 550c are formed along the + Z′-axis side of the long side of the piezoelectric device 500 on the + X-axis side, and overlap each other in the Y′-axis direction. Is formed. A first side electrode 552a, a second side electrode 552b, and a third side electrode 552c are formed on the side surfaces of the first castellation 550a, the second castellation 550b, and the third castellation 550c. The first side electrode 552a and the second side electrode 552b are formed by the first film 192A and the second film 192B, and the third side electrode 552c is formed by the metal film 112, the first film 192A, and the second film 192B. .

  The piezoelectric device 500 is preferable because each castellation can be made large by forming the first castellation 550a to the third castellation 550c on the long side, and etching becomes easy.

<Configuration of Piezoelectric Device 600>
FIG. 12B is an exploded perspective view of the piezoelectric device 600. The piezoelectric device 600 is formed by stacking the piezoelectric vibrating piece 520, the base 540, and the lid 210. The piezoelectric device 600 uses a lid 210 instead of the lid 510 in the piezoelectric device 500.

  In the piezoelectric device 600, since the lid 210 can be easily formed as in the piezoelectric device 200, the number of manufacturing steps can be reduced. Further, like the piezoelectric device 500, since the first castellation 550a and the second castellation 550b are formed widely, it is preferable because the first castellation 550a and the second castellation 550b can be easily formed by etching. .

  As described above, the optimal embodiment of the present invention has been described in detail. However, as will be apparent to those skilled in the art, the present invention can be implemented with various modifications and variations within the technical scope thereof. Moreover, the features of each embodiment can be implemented in various combinations.

  For example, in the method for manufacturing the piezoelectric device 100 shown in FIG. 6, the metal film 112 is formed on the lid wafer W110 in step S103, but even if the metal film 112 is formed together with the connection terminals in step S106 instead of step S103. good. In this case, since the metal film 112 is formed in common with a part of the chromium (Cr) layer of the first film 192A, the third side surface electrode 152c shown in FIG. 3B has the first film 192A and the second film 192A. It is formed only by the film 192B.

  In the above-described embodiment, the vibrating portion is rectangular. However, other shapes such as a tuning fork shape, an elliptical shape, and a circular shape may be used. Further, although the piezoelectric vibrating piece is an AT cut crystal, a crystal such as a Z cut or a BT cut may be used. Furthermore, although the piezoelectric vibrating piece is formed of quartz, a piezoelectric material other than quartz, for example, lithium tantalate, lithium niobate, or piezoelectric ceramic may be used.

100, 195, 200, 250, 300, 400, 500, 600 ... Piezoelectric device 101 ... Cavity 110, 210, 310, 510 ... Lid 112, 212 ... Metal film 120, 320, 520 ... Piezoelectric vibrating piece 122, 322, 522 ... Frame part 124 ... Vibration part 126 ... Connection part 128 ... Excitation electrode 130, 130a, 130b ... Extraction electrode 132 ... Through groove 140, 340, 540 ... Base 141 ... Ground electrode 142 ... Mounting electrode 144 ... Notch part electrode 145 ... Connection terminal 148a, 148b ... Notch 150a, 350a ... First castellation 150b, 350b ... Second castellation 150c, 350c ... Third castellation 152a, 352a ... First side electrode 152b, 352b ... Second side Electrodes 152c, 352c ... third side electrode 160 ... bonding material 171 ... scribe lines 192A ... first film 192B ... second layer 197,251 ... side electrode W110 ... lid wafer W120 ... piezoelectric wafer W140 ... base wafer

Claims (8)

A vibration part that vibrates at a predetermined frequency; a frame part that surrounds the vibration part away from the vibration part; and a connecting part that connects the vibration part and the frame part; and both main surfaces of the vibration part Excitation electrodes are formed on each of the excitation electrodes. The extraction electrodes are led out from the excitation electrodes to the frame portion via the connecting portions, and a first castellation recessed inward from the outer periphery is formed on the outer periphery of the frame portion. A formed piezoelectric vibrating piece;
Formed into a rectangular shape including a long side and a short side, the base is joined to one main surface, and a ground electrode is formed at one corner of the other main surface;
A lid that is bonded to the frame portion and forms a cavity together with the base to seal the vibrating portion to the cavity;
A second castellation is formed in the area corresponding to the one corner of the base so as to be recessed from the outer periphery of the base,
A metal film is formed on the lid so as to cover a region facing the cavity,
The first castellation and the second castellation overlap in the height direction, and the ground electrode and the extraction electrode do not overlap in the height direction,
A piezoelectric device in which the metal film is connected to the ground electrode via the first castellation and the second castellation. A vibration part that vibrates at a predetermined frequency; a frame part that surrounds the vibration part away from the vibration part; and a connecting part that connects the vibration part and the frame part; and both main surfaces of the vibration part Excitation electrodes are formed on each of the excitation electrodes. The extraction electrodes are led out from the excitation electrodes to the frame portion via the connecting portions, and a first castellation recessed inward from the outer periphery is formed on the outer periphery of the frame portion. A formed piezoelectric vibrating piece;
Formed into a rectangular shape including a long side and a short side, the base is joined to one main surface, and a ground electrode is formed at one corner of the other main surface;
A lid that is bonded to the frame portion and forms a cavity together with the base to seal the vibrating portion to the cavity;
A second castellation is formed in the area corresponding to the one corner of the base so as to be recessed from the outer periphery of the base,
A metal film is formed on the lid so as to cover a third castellation recessed from the outer periphery of the lid and a surface opposite to the surface facing the cavity,
The first castellation, the second castellation, and the third castellation overlap in the height direction, and the ground electrode and the extraction electrode do not overlap in the height direction,
A piezoelectric device in which the metal film is connected to the ground electrode via the first castellation, the second castellation, and the third castellation.   The piezoelectric device according to claim 1, wherein the first castellation is formed at a corner of the base.   The piezoelectric device according to claim 1, wherein the first castellation is formed along the short side of the base.   The piezoelectric device according to claim 1, wherein the first castellation is formed on a part of the long side of the base.   The piezoelectric device according to claim 1, wherein the metal film and the ground electrode are connected by a side electrode made of the same material as the ground electrode.   The piezoelectric device according to claim 1 or 2, wherein the metal film and the ground electrode are connected by a side electrode made of the same material as the metal film. The connection between the metal film and the ground electrode is made by a side electrode made of the same material as the metal film,
The side electrode is connected to the ground electrode with a necessary minimum area capable of ensuring electrical connection with the ground electrode and is exposed to the ground electrode surface and connected.
The piezoelectric device according to claim 1 or 2, wherein a material of the metal film and the side electrode is chromium, tungsten, or molybdenum.