JP2014086894A - Piezoelectric device and manufacturing method of piezoelectric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a lead-out electrode from being damaged or deteriorated even when chipping occurs in a piezoelectric vibration piece, and to prevent lead-out electrode damage or conductive film cutting caused by chipping when cutting a piezoelectric wafer or the like during manufacture.SOLUTION: A piezoelectric device comprises: a piezoelectric vibration piece 130 which includes a frame part 132 surrounding a vibrating part 131 and in which lead-out electrodes 137, 138 electrically connected with excitation electrodes 135, 136 provided in the vibrating part 131 are provided on a rear side of the frame part 132; and a base section 120 which is bonded to a rear side of the piezoelectric vibration piece 130 via a bond 141 and in which a castellation 123 is provided correspondingly to the lead-out electrodes 137, 138. Conductive films 151, 151a are formed via the castellation 123 so as to be connected from external electrodes 150, 150a on a rear side of the base section 120 to the lead-out electrodes 137, 138 and in the piezoelectric vibration piece 130, a step 139 is formed in an end portion 132a of the frame part 132, namely, on the rear side corresponding to the castellation 123.

Description

  The present invention relates to a piezoelectric device and a method for manufacturing a piezoelectric device.

  As a piezoelectric device, a lid portion is bonded to the surface (one main surface) of a piezoelectric vibrating piece such as a crystal vibrating piece via a non-conductive bonding agent, and the back surface (the other main surface) is also non-conductive. A type in which a base portion is bonded via a bonding agent is known. A piezoelectric vibrating piece used in this type includes a vibrating portion that vibrates at a predetermined frequency and a frame portion that is formed so as to surround the vibrating portion. In addition, excitation electrodes are formed on the front and back surfaces of the vibration part of the piezoelectric vibrating piece, respectively, and extraction electrodes are formed from each excitation electrode to the frame part, and this extraction electrode is electrically connected to the external electrode of the base part. It is connected.

  For example, Patent Document 1 discloses a piezoelectric device having a structure in which a lead electrode is connected to an external electrode through a castellation (notch portion) formed on a side portion of a base portion (Patent Document 1). (See FIG. 2 etc.). In this piezoelectric device, after a lid wafer and a base wafer are bonded to the front and back surfaces of a piezoelectric wafer having a plurality of piezoelectric vibrating reeds, a conductive film up to an extraction electrode is formed along with the formation of external electrodes in the base portion, and then scribing is performed. Individual finished products are cut by cutting along the line.

JP2011-176787A

  However, in the piezoelectric device of Patent Document 1, if a force is applied to the outer periphery of the piezoelectric vibrating piece to cause chipping (chips, cracks, cracks, etc.), damage to the extraction electrode and airtightness of the internal space (in the cavity) may be impaired. is there. In particular, in the manufacturing stage of the piezoelectric device, there is a high possibility that chipping of the piezoelectric wafer occurs in the process of cutting the piezoelectric wafer or the like, and the extraction electrode is likely to be damaged or deteriorated. Furthermore, if the amount of the bonding agent is large when bonding the base wafer to the piezoelectric wafer, the bonding agent protrudes from between the piezoelectric wafer and the base wafer to the outside. If a conductive film is formed on the protruding portion, the conductive film is cut when cutting along the scribe line, and the electrical connection between the extraction electrode and the external electrode cannot be secured, resulting in a defective product. There is a problem of making it.

  In view of the above circumstances, in the present invention, even when the piezoelectric vibrating piece is chipped, the extraction electrode is prevented from being damaged or deteriorated, and the extraction electrode is damaged due to chipping when the piezoelectric wafer or the like is cut. It is an object of the present invention to provide a piezoelectric device and a method for manufacturing the piezoelectric device that can prevent the occurrence of defective products by preventing cutting of the conductive film and the like.

  In the present invention, there is provided a piezoelectric vibrating piece having a frame portion surrounding the vibrating portion and having an extraction electrode electrically connected to an excitation electrode provided on the vibrating portion on the back surface of the frame portion, and on the back surface of the piezoelectric vibrating piece. A base portion bonded through a non-conductive bonding agent and provided with a notch portion corresponding to the extraction electrode, and connected to the extraction electrode from the external electrode on the back surface of the base portion. In the piezoelectric device in which the conductive film is formed through the portion, the piezoelectric vibrating piece has a stepped portion on the back surface side corresponding to the notch at the end of the frame portion.

  Further, the stepped portion may be formed over the entire outer periphery of the frame portion. Further, the extraction electrode may be formed away from the stepped portion. Further, the extraction electrode may be formed up to the step portion, and the extraction electrode and the conductive film may be connected at the step portion. Further, the bonding material may be arranged so as to protrude to the stepped portion.

  In the present invention, a plurality of piezoelectric vibrating reeds having a vibrating part including an excitation electrode and a frame part surrounding the vibrating part are formed on the piezoelectric wafer, and an extraction electrode electrically connected to the excitation electrode is a frame part. A piezoelectric vibrating piece forming step formed on the back surface of the substrate, and a plurality of base portions corresponding to the piezoelectric vibrating piece are formed on the base wafer, and an opening is formed between adjacent base portions and corresponding to the extraction electrode. A base portion forming step to be formed, a bonding step in which the base wafer is bonded to the back surface of the piezoelectric wafer via a non-conductive bonding agent, and a part of the back surface of the base portion from the inner surface of the opening portion A conductive film forming process in which a conductive film connected to the extraction electrode is formed, and individual piezoelectric devices are formed by cutting the piezoelectric wafer and the base wafer along a scribe line set including a part of the opening. Is A piezoelectric vibration piece forming step including a region exposed at an end of the frame portion and exposed from the opening of the base wafer on the back surface of the piezoelectric wafer. A recess forming step of forming a recess having a width wider than the width of the line;

  In the recess forming step, the recess may be formed in a lattice shape along the piezoelectric vibrating piece formed on the piezoelectric wafer. Further, the piezoelectric wafer forming step may include a thinning step for thinning a vibrating portion formed on the piezoelectric wafer, and the concave portion forming step may be performed simultaneously with the thinning step.

  According to the present invention, even when chipping occurs in the piezoelectric vibrating piece, damage or deterioration of the extraction electrode is prevented, and damage to the extraction electrode due to chipping when cutting the piezoelectric wafer or the like during manufacturing, Cutting of the conductive film can be prevented. Therefore, it is possible to reduce the occurrence of defective products that occur in the manufacturing process of the piezoelectric device, improve the productivity of the piezoelectric device, and provide a piezoelectric device with high quality and high reliability.

1 is an exploded perspective view of a piezoelectric device according to a first embodiment. (A) is a top view in the area | region S of FIG. 1, (b) is sectional drawing along the AA of (a). (A) is a top view which shows a piezoelectric wafer, (b) is a top view which shows a base wafer. The piezoelectric device which concerns on 2nd Embodiment is shown, (a) is a top view, (b) is sectional drawing along the BB line of (a). It is a top view which shows the piezoelectric device which concerns on 3rd Embodiment. (A) is a top view which shows the other example of a piezoelectric wafer, (b) is a top view which shows the other example of a base wafer. The piezoelectric device which concerns on 4th Embodiment is shown, (a) is a top view, (b) is sectional drawing along CC line of (a).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to this. Further, in the following embodiments, in order to describe the embodiments in the drawings, the scale is appropriately changed and expressed by partially enlarging or emphasizing the description. The hatched portion in the drawing represents a cross section of the conductive film and the bonding material.

<First Embodiment>
(Configuration of the piezoelectric device 100)
The piezoelectric device 100 according to the first embodiment will be described.
As shown in FIGS. 1 and 2, the piezoelectric device 100 includes a lid portion 110, a piezoelectric vibrating piece 130, and a base portion 120. In the following description, 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 X and Y-axis directions are perpendicular to the axial direction of the piezoelectric vibrating piece 130. The direction, that is, the short side direction of the piezoelectric device 100 will be described as the Z-axis direction. FIG. 2A is an enlarged plan view of the region S of FIG. 1 and shows the lid portion 110 transparently for easy understanding.

  When viewed from the Y-axis direction, the lid portion 110 is formed in a rectangular shape having a long side in the X-axis direction and a short side in the Z-axis direction, and a center on the back surface (the surface on the −Y side) of the lid portion 110. This region has a central portion 111 having a concave shape, and a bonding surface 112 is formed so as to surround the central portion 111. The lid portion 110 is disposed on a surface (+ Y side surface) of a piezoelectric vibrating piece 130 described later, and the bonding surface 112 is bonded to the frame portion 132 of the piezoelectric vibrating piece 130 via a non-conductive bonding material 140. . For example, an AT-cut quartz material is used for the base portion 120 and the piezoelectric vibrating piece 130 described later including the lid portion 110. The AT cut has an advantage that a good frequency characteristic can be obtained when a piezoelectric device such as a crystal resonator is used near room temperature, and the three crystal axes of the artificial quartz, the electrical axis, the mechanical axis, and the optical axis. Among them, this is a processing method of cutting at an angle of 35 ° 15 ′ around the crystal axis with respect to the optical axis.

  When viewed from the Y-axis direction, the base portion 120 is formed in a rectangular shape having a long side in the X-axis direction and a short side in the Z-axis direction, similar to the lid portion 110, and the surface of the base portion 120 (on the + Y side) Surface) has a central portion 121 having a concave central region, and a joint surface 122 is formed so as to surround the central portion 121. The base portion 120 is disposed on the back surface (the surface on the −Y side) of the piezoelectric vibrating piece 130, and the bonding surface 122 is bonded to the frame portion 132 of the piezoelectric vibrating piece 130 via the bonding material 141.

  Of the four corners of the base portion 120, the casters having the same shape formed by cutting out the corner portions of the base portion 120 at the corner portions on the + X side and the + Z side and the corner portions thereof. A notch 123 is provided. As shown in FIG. 2B, the castellation 123 has an inclined surface in which a central portion in the Y-axis direction protrudes outward rather than a planar shape along the Y-axis direction. This is due to the anisotropy of the AT-cut quartz material forming the base portion 120. That is, since the etching rate varies depending on the anisotropy of the AT-cut quartz material, the castellation 123 is formed as an inclined surface.

  External electrodes 150 and 150 a for electrically connecting the piezoelectric device 100 and a circuit board or the like are provided on the back surface (the surface on the −Y side) of the base portion 120. Further, the castellation 123 of the base portion 120 is provided with conductive films 151 and 151a respectively following the external electrodes 150 and 150a. As shown in FIG. 2B, the conductive film 151 is formed so as to cover the castellation 123, and further on the back surface (the surface on the −Y side) of the frame portion 132 and exposed by the castellation 123. Is formed. The same applies to the connection electrode 151a. The conductive films 151 and 151a are electrically connected to lead electrodes 137b and 138 (both will be described later) formed on the back surface of the frame portion 132, respectively. As shown in FIG. 2B, the extraction electrode 137b is covered with the conductive film 151 so as not to come into contact with the outside air, thereby preventing corrosion of the extraction electrode 137b. Similarly, the extraction electrode 138 is covered with the conductive film 151a.

  The external electrodes 150 and 150a and the conductive films 151 and 151a are integrally formed by forming a conductive metal film by sputtering. However, the external electrodes 150 and 150a and the conductive films 151 and 151a may be formed separately. For example, an external electrode may be formed in advance on the back surface of the base portion 120, and a conductive film may be provided so as to connect the external electrode and the extraction electrodes 137b and 138.

  The conductive metal film forming the external electrodes 150 and 150a and the conductive films 151 and 151a is formed of a chromium (Cr) layer, a nickel tungsten (Ni-W) layer, and a gold (Au) layer in this order. It has a three-layer structure. The reason why chromium is used is that it has excellent adhesion to the crystal material constituting the base portion 120 and the piezoelectric vibrating piece 130 and diffuses into the nickel tungsten layer after film formation, and an oxide film ( This is to improve the corrosion resistance of the metal film. Note that the metal film may be formed by vacuum evaporation instead of film formation by sputtering. Further, the conductive metal film may have a two-layer structure in which a nickel tungsten (Ni—W) layer and a gold (Au) layer are formed in this order.

  The piezoelectric vibrating piece 130 includes a vibrating part 131 that vibrates at a predetermined frequency, a frame part 132 that surrounds the vibrating part 131, and a connecting part 133 that connects the vibrating part 131 and the frame part 132. A through hole 134 that penetrates in the Y-axis direction is formed between 131 and the frame portion 132. The vibrating part 131 and the connecting part 133 are formed so that the thickness in the Y-axis direction is thinner than that of the frame part 132. The piezoelectric vibrating piece 130 is formed in a rectangular shape having a long side in the X-axis direction and a short side in the Z-axis direction as a whole.

  Further, the frame portion 132 of the piezoelectric vibrating piece 130 is provided with a step portion 139 along the outer periphery of the frame portion 132 at the position of the end portion 132 a and the back surface (the surface on the −Y side). The step portion 139 is formed on the back surface of the end portion 132 a of the frame portion 132 so as to make a round of the frame portion 132 in the X-axis direction and the Z-axis direction along the outer periphery of the frame portion 132. By this stepped portion 139, the end portion 132a of the frame portion 132 is thinner in the Y-axis direction than other portions. The thickness of the end portion 132a in the Y-axis direction is the same as that of the vibrating portion 131, but is not limited thereto. The step portion 139 is also provided at a position corresponding to the castellation 123, and is exposed by the castellation 123.

  As shown in FIG. 2B, the stepped portion 139 is formed by cutting the back surface of the end portion 132a of the frame portion 132 into an L-shaped cross section. The length of the step portion 139 in the Y-axis direction (depth from the back surface of the frame portion 132) corresponds to the depth of the vibrating portion 131 from the surface of the frame portion 132. Further, the length of the step portion 139 in the X-axis direction and the Z-axis direction is smaller than the width of the castellation 123 provided in the base portion 120 as shown in FIG. Further, as shown in FIG. 2B, the conductive films 151 and 151a are formed up to the step portion 139 while covering the castellation 123, the bonding material 141, and the extraction electrodes 137b and 138.

  Excitation electrodes 135 and 136 are respectively formed on the front surface (+ Y side surface) and the back surface (−Y side surface) of the vibrating portion 131 of the piezoelectric vibrating piece 130. An extraction electrode 137 that is electrically connected to the excitation electrode 135 is formed on the front surface (+ Y side surface) and the back surface (−Y side surface) of the frame portion 132 of the piezoelectric vibrating piece 130. As shown in FIG. 1, the extraction electrode 137 is extracted in the −X-axis direction from the excitation electrode 135 through the surface of the coupling portion 133 (the surface on the + Y side) to the surface of the frame portion 132, and then the frame portion 132. The lead electrode 137a is extended to the + Z-axis direction and then bent and pulled out in the + X-axis direction, and is formed up to the + X side and + Z side regions of the surface of the frame portion 132. The lead electrode 137 a is led to a rectangular lead electrode 137 b formed on the back surface of the frame portion 132 via a lead electrode 137 c formed on the inner surface of the frame portion 132.

  As shown in FIG. 2A, the extraction electrode 137 b is formed so as to be separated from the step portion 139, and is arranged so that a part on the + X side and the + Z side is exposed by the castellation 123. In addition, even when the base portion 120 is bonded to the piezoelectric vibrating piece 130 via the bonding material 141, the extraction electrode 137b is formed so as to be exposed from the end portion of the bonding material 141 as shown in FIG. ing.

  The extraction electrode 137a is formed away from the end portion 132a of the frame portion 132. Therefore, as shown in FIG. 2B, when the lid portion 110 is bonded to the piezoelectric vibrating piece 130, the outer edge of the extraction electrode 137 a is covered with the bonding material 140. Thereby, the extraction electrode 137a is prevented from coming into contact with the outside air, and corrosion due to moisture in the outside air is prevented.

  An extraction electrode 138 that is electrically connected to the excitation electrode 136 is formed on the back surface (the surface on the −Y side) of the frame portion 132 of the piezoelectric vibrating piece 130. As shown in FIG. 1, the extraction electrode 138 is drawn in the −X-axis direction from the excitation electrode 136 through the back surface (the surface on the −Y side) of the coupling portion 133 to the back surface of the frame portion 132. Are formed in a rectangular shape on the −X side and the −Z side. The extraction electrode 138 and the extraction electrode 137 are not electrically connected, and the extraction electrode 138 and the extraction electrode 137 b are formed at diagonal positions on the back surface of the frame portion 132. Although not shown, the extraction electrode 138 is formed away from the stepped portion 139 as in the case of the extraction electrode 137 b shown in FIG. 2A, and a part on the −X side and the −Z side is formed by the castellation 123. It is arranged so that it is exposed (see Figure 1). Further, the extraction electrode 138 is exposed from the end portion of the bonding material 141 similarly to the extraction electrode 137b shown in FIG. 2A even when the base portion 120 is bonded to the piezoelectric vibrating piece 130 via the bonding material 141. It is formed as follows.

  The excitation electrodes 135 and 136 and the extraction electrodes 137 and 138 are conductive metal films and are formed by sputtering. The conductive metal film has a two-layer structure in which a nickel tungsten (Ni-W) layer and a gold (Au) layer are stacked in this order. Note that chromium (Cr) may be formed as a base film of the metal film.

  As described above, according to the first embodiment, since the step portion 139 is provided at the end 132a of the frame portion 132 of the piezoelectric vibrating piece 130, the piezoelectric device 100 is mounted on the circuit board or is transported. Even if chipping occurs at the outer edge of the frame portion 132, cracks and the like are suppressed up to the step portion 139, so that the extraction electrode 137b and the like can be prevented from touching the outside air to cause corrosion and the like, and the operation reliability of the piezoelectric device 100 is improved. Can be secured.

(Method for Manufacturing Piezoelectric Device 100)
Next, a method for manufacturing the piezoelectric device 100 will be described.
First, a lid wafer (not shown), a piezoelectric wafer AW1, and a base wafer BW are prepared. Each wafer is cut out from the quartz crystal body by AT cut. Note that not only the piezoelectric wafer AW1, but also a lid wafer and a base wafer BW are crystal wafers that have been AT-cut. This is because, in the manufacturing process of the piezoelectric device 100, each wafer is heated and thermally expanded in the process of bonding the wafers and forming the metal film on the surface of the wafer, but the wafers having different thermal expansion coefficients are used. This is because deformation or cracking may occur due to the difference in thermal expansion coefficient.

[Piezoelectric vibrating piece forming process]
As shown in FIG. 3A, the piezoelectric wafer AW1 has a rectangular vibrating portion 131 and a frame surrounding the vibrating portion 131 in each of the regions corresponding to the plurality of piezoelectric vibrating pieces 130 by photolithography and etching. The part 132 and the connection part 133 which connects the vibration part 131 and the frame part 132 are formed. A through hole 134 is formed between the vibration part 131 and the frame part 132. Subsequently, the vibrating unit 131 is processed so as to have a small thickness (width in the Y-axis direction) by etching or the like so as to have a desired frequency characteristic (a thinning step). Note that it is arbitrary whether or not to perform the thinning step.

  Further, a concave portion 160 is formed on the back surface (the surface on the −Y side) of the piezoelectric wafer AW1 at a position corresponding to the end portion 132a of the frame portion 132 (a concave portion forming step). The recesses 160 are formed in a lattice pattern by the recesses 160a in the X-axis direction and the recesses 160b in the Z-axis direction so as to correspond to the scribe lines SL1 and SL2. The width (length in the Z-axis direction) D1 of the recess 160a is wider than the width (length in the Z-axis direction) L1 of the scribe line SL1. Further, the width (length in the X-axis direction) D2 of the recess 160b is wider than the width (length in the X-axis direction) L2 of the scribe line SL2. Here, the scribe lines SL1 and SL2 are lines that are cut (diced) by a dicing saw.

  The recess forming step and the thinning step are performed simultaneously, but each step may be performed separately. When the thickness of the vibrating portion 131 is substantially the same as the depth of the concave portion 160, it can be processed simultaneously by etching or the like, thereby shortening the manufacturing process. Further, the width D1 of the recess 160a and the width D2 of the recess 160b are formed the same, but may be different. In either case, the width is arbitrary as long as it is wider than the scribe lines SL1 and SL2. Note that the recess forming step and the thinning step are not limited to being performed by etching, and may be performed by mechanical cutting or the like.

  An excitation electrode 135 and an extraction electrode 137 a electrically connected to the excitation electrode 135 are formed on the surface of the vibration part 131. An excitation electrode 136, an extraction electrode 138 electrically connected to the excitation electrode 136, and an extraction electrode 137 b are formed on the back surface of the vibration part 131. On the inner surface of the frame portion 132, an extraction electrode 137c that electrically connects the extraction electrodes 137a and 137b is formed. For example, the excitation electrodes 135 and 136 and the extraction electrodes 137 and 138 are masked by photolithography only on the surface of the piezoelectric wafer AW1 where no electrode is formed, and the surface of the piezoelectric wafer AW1 is sputtered by nickel tungsten ( A thin film made of Ni—W is formed, and a thin film made of gold (Au) is formed thereon. The film formation may be performed by vacuum evaporation.

[Base part forming process]
As shown in FIG. 3B, the base wafer BW has a rectangular and concave central portion formed on the surface (+ Y side surface) corresponding to the plurality of base portions 120 by photolithography and etching. 121 is formed. In addition, castellations 123 are formed at two diagonal positions of the four corners of each base portion 120 (that is, between adjacent base portions 120 and facing the extraction electrodes 137b and 138). An opening 170 is formed. Each of the openings 170 is arranged so that a part thereof enters the scribe lines SL1 and SL2. The central portion 121 and the opening 171 are formed by, for example, photolithography and half etching or etching, but may be formed by mechanical cutting or the like. This base portion forming step is performed in parallel with the piezoelectric vibrating piece forming step.

[Lid part forming process]
Similarly to the base wafer BW, the lid wafer (not shown) has a rectangular and concave central portion 111 formed on each of the back surfaces (surfaces on the −Y side) corresponding to the plurality of lid portions 110 by photolithography and etching. Is formed. This lid portion forming step is performed in parallel with the piezoelectric vibrating piece forming step and the base portion forming step.

[Jointing process]
Subsequently, the lid wafer is bonded to the surface of the piezoelectric wafer AW1 via the bonding material 140 in a vacuum atmosphere. Similarly, the base wafer BW is bonded to the back surface of the piezoelectric wafer AW1 via the bonding material 141. Each of the lid wafer and the base wafer BW is bonded in a state of being positioned with respect to the piezoelectric wafer AW1. The bonding material 140 is disposed between the peripheral portion 112 of the lid portion 110 and the surface of the frame portion 132, respectively. The bonding material 141 is disposed between the back surface of the frame portion 132 and the peripheral portion 122 of the base portion 120. In a state where the joining process has been performed, the vibration part 131 is housed in an internal space (cavity) surrounded by the center part 111 and the frame part 132 of the lid part and the center part 121 of the base part 120. The internal space may be filled with an inert gas other than vacuum.

[Conductive film formation process]
Subsequently, external electrodes 150 and 150a and conductive films 151 and 151a electrically connecting the external electrodes 150 and 150a and the extraction electrodes 137b and 138 are formed on the back surface (the surface on the −Y side) of the base wafer BW. It is formed. The external electrodes 150 and 150a and the conductive films 151 and 151a are made of the same conductive metal film and are formed almost simultaneously. For example, the external electrodes 150 and 150a and the conductive films 151 and 151a are formed by forming a metal film at a predetermined location by sputtering using a metal mask or the like. However, it is not limited to forming the external electrodes 150 and 150a and the conductive films 151 and 151a at the same time. For example, the external electrodes 150 and 150a are formed in advance in the above-described base portion forming step, and the conductive films 151 and 151a are later formed. May form

  The conductive film 151 is formed up to the side surface of the opening 170, the side surface of the bonding material 141, and the back surface of the frame portion 132, and is connected to the extraction electrode 137b (see FIG. 2B). Similarly, the conductive film 151 a is formed up to the side surface of the opening 170, the side surface of the bonding material 141, and the back surface of the frame portion 132, and is connected to the extraction electrode 138. As a metal film for forming the external electrodes 150 and 150a and the conductive films 151 and 151a, chromium (Cr) is formed as a base film, and nickel tungsten (Ni-W) and gold (Au) are sequentially formed on the base film. A film is formed. The film formation may be performed by vacuum evaporation.

[Cutting process]
Subsequently, the bonded lid wafer, piezoelectric wafer AW1, and base wafer BW are cut (diced) by a dicing saw along the scribe lines SL1 and SL2 in the X-axis direction and the Z-axis direction. As shown in FIG. 3A, the scribe lines SL1 and SL2 are set in the recesses 160a and 160b in the piezoelectric wafer AW1. Further, as shown in FIG. 3B, the scribe lines SL1 and SL2 are set so as to include a part of the opening 170 in the base wafer BW.

  Since the widths D1 and D2 of the recesses 160a and 160b are wider than the widths L1 and L2 of the scribe lines SL1 and SL2, the portions where the recesses 160a and 160b remain after dicing become the stepped portion 139. Further, since the scribe lines SL1 and SL2 include a part of the opening 170, the castellation 123 is formed after cutting. The piezoelectric device 100 is completed by cutting into individual piezoelectric devices 100 by this cutting process.

  In this way, since the scribe lines SL1 and SL2 are in the recesses 160a and 160b in the cutting process, even when chipping occurs in the piezoelectric vibrating piece 130 during dicing, cracks and chips are caused by the step portion 139 (recess 160). The chipping is stopped, and the progress of chipping in the inner direction of the piezoelectric device 100 is suppressed. Accordingly, damage to the extraction electrode 137b, corrosion of the extraction electrode 130b by contact with the outside air, and poor bonding between the piezoelectric vibrating piece 130 and the base portion 120 are prevented, and generation of defective products is prevented and high reliability is achieved. A piezoelectric device can be provided. Further, since the concave portions 160 are formed in a lattice shape by the concave portions 160a and 160b, it is easy to form the concave portions 160 using patterning, etching, and the like in the piezoelectric vibrating piece forming step, and an increase in manufacturing cost can be suppressed. .

Second Embodiment
(Configuration of piezoelectric device 200)
Next, the piezoelectric device 200 according to the second embodiment will be described. In the following description, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified. 4A is a plan view in which a part of the piezoelectric device 200 is enlarged, and the enlarged part is a part corresponding to the region S in FIG. Further, FIG. 4A shows the lid portion through like the FIG. 2A.

  As shown in FIGS. 4A and 4B, the piezoelectric device 200 includes a lid portion 110, a piezoelectric vibrating piece 230, and a base portion 120. The lid part 110 and the base part 120 are the same as those used in the piezoelectric device 100 according to the first embodiment. Further, in the piezoelectric vibrating piece 230, a vibrating part 131, a connecting part 133, a penetrating part 134, excitation electrodes 135 and 136, and a step part 139 are the same as those of the piezoelectric device 100 of the first embodiment.

  On the piezoelectric vibrating piece 230, an extraction electrode 237 electrically connected to the excitation electrode 135 is formed. An extraction electrode 237 a that is extracted from the excitation electrode 135 is formed on the surface (+ Y side surface) of the frame portion 132. An extraction electrode 237b electrically connected to the extraction electrode 237a is formed on the back surface (the surface on the −Y side) of the frame portion 132 via an extraction electrode 237c formed on the inner surface of the frame portion 132. . The extraction electrodes 237a and 237c are substantially the same as the extraction electrodes 137a and 137c of the first embodiment. The extraction electrode 237 b includes a portion corresponding to the castellation 123, and is formed in a rectangular shape over the step portion 139. However, the extraction electrode 237b is disposed at a position separated from the end portion 132a of the frame portion 132, as shown in FIG. Although not shown, the extraction electrode (corresponding to the extraction electrode 138 in the first embodiment) disposed diagonally to the extraction electrode 237b on the back surface of the frame portion 132 is similarly formed in a rectangular shape over the step portion 139. Is done.

  As shown in FIG. 4B, the bonding material 142 extends to the stepped portion 139, and a conductive film 251 is formed so as to cover the end portion of the bonding material 142. The conductive film 251 is formed together with the external electrode 250 formed on the back surface of the lid portion 120, and electrically connects the external electrode 250 and the extraction electrode 237b.

  Thus, according to the second embodiment, since the extraction electrode 237b is formed up to the step portion 139, even when the bonding material 142 protrudes from the castellation 123, the conductive film 251 can be connected to the extraction electrode 237b. , Electrical connection failure can be avoided. Further, since the protrusion of the bonding material 142 is stopped by the step portion 139, the extraction electrode 237b formed on the step portion 139 and the conductive film 251 can be reliably connected.

(Method for manufacturing piezoelectric device 200)
Next, a method for manufacturing the piezoelectric device 200 will be described. It should be noted that the AT-cut lid wafer, piezoelectric wafer, and base wafer are used in the same manner as the method for manufacturing the piezoelectric device 100. Each process in the method for manufacturing the piezoelectric device 200 is substantially the same as each process described in the method for manufacturing the piezoelectric device 100. The following description will focus on the differences in each process.

  In the piezoelectric vibrating piece forming step, the extraction electrode 237b is formed in a rectangular shape from the region corresponding to the frame portion 132 to the concave portion on the back surface of the piezoelectric wafer (see FIG. 4A). However, the extraction electrode 237b is formed in a state separated from the scribe line. The extraction electrodes 237a and 237c are formed in the same manner as the extraction electrodes 137a and 137c in the piezoelectric device 100.

  In the bonding step, the base wafer is bonded to the back surface of the piezoelectric wafer via the bonding material 142 in a vacuum atmosphere. At this time, the bonding material 142 protrudes from between the piezoelectric wafer and the base wafer, but is stopped by the recess formed in the piezoelectric wafer (see the recess 160 formed in the piezoelectric wafer AW1 in FIG. 3A). It does not enter the inside (that is, the step 139). It should be noted that the bonding material 142 may be disposed slightly larger in order to avoid a gap between the piezoelectric wafer and the base wafer after bonding, and in this case, the bonding material 142 tends to protrude from both.

  In the conductive film forming process, the external electrode 250 is formed on the back surface of the base wafer, and the side surface of the opening (see the opening 170 formed in the base wafer BW in FIG. 3B) is bonded. A conductive film 251 is formed to the concave portion together with the end portion of the material 142. Note that the connection between the extraction electrode 237b and the conductive film 251 is made in the concave portion (the subsequent step portion 139). The outer peripheral edge of the extraction electrode 237b is covered with the conductive film 251 in the recess.

  In the cutting step, dicing is performed along the scribe line, as in the method for manufacturing the piezoelectric device 100 according to the first embodiment. Since the scribe line is set in the recess (see FIG. 2), the bonding material 142 and the conductive film 251 are separated from the scribe line, and the conductive film 251 is not cut by dicing. That is, the bonding material 142 is stopped so as not to enter the concave portion, and the conductive film 251 is formed on the bonding material 142, thereby separating the conductive film 251 from the scribe line. The piezoelectric device 200 is completed by this cutting process.

  As described above, even when the bonding material 142 protrudes from between the piezoelectric wafer and the base wafer, the bonding material 142 is stopped by the concave portion, and the conductive film 251 covering the bonding material 142 is prevented from protruding to the scribe line. Therefore, the conductive film 251 is not inadvertently cut in the cutting step, and generation of defective products can be prevented.

<Third Embodiment>
(Configuration of piezoelectric device 300)
Next, a piezoelectric device 300 according to the third embodiment will be described. In the following description, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified. 5 is an enlarged plan view of a part of the piezoelectric device 300, and the enlarged portion corresponds to the region S in FIG. Further, FIG. 5 shows the lid portion in a transparent manner as in FIG.

  Although not shown, the piezoelectric device 300 has a lid portion and a base portion similar to those of the piezoelectric device 100 according to the first embodiment bonded to the front and back surfaces of the piezoelectric vibrating piece 330, respectively. In the piezoelectric vibrating piece 330, the vibration unit 131, the coupling unit 133, the penetration unit 134, and the excitation electrodes 135 and 136 (not shown) are the same as those of the piezoelectric device 100.

  As shown in FIG. 5, the piezoelectric vibrating piece 330 has step portions 139 a at the corners at the end 132 a of the frame portion 132. The step portion 139a is narrower than the width of the castellation 123, and is formed in an L shape extending from the corner portion of the frame portion 132 beyond the castellation 123 in the −X axis direction and the −Z axis direction. In addition, the thickness of the frame part 132 in the step part 139a is formed in the same thickness as the vibration part 131 similarly to the step part 139 of 1st Embodiment. The extraction electrode 137b is formed away from the step portion 139a. Although not shown, the extraction electrode (extraction electrode 138 of the first embodiment) disposed diagonally to the extraction electrode 137b on the back surface of the frame portion 132 is also formed in a rectangular shape spaced apart from the step portion 139a. Is done.

  As described above, according to the third embodiment, since the step portion 139a is formed corresponding to the castellation 123, the same effect as the piezoelectric device 100 of the first embodiment can be obtained. Furthermore, since the step portion 139a is partially provided at the corner portion of the frame portion 132, the processing range of the piezoelectric vibrating piece 330 with respect to the frame portion 132 is small, and the joint surface with the base portion can be widened. The reliability of the seal can be improved and the rigidity of the entire piezoelectric device 300 can be secured.

(Method for Manufacturing Piezoelectric Device 300)
Next, a method for manufacturing the piezoelectric device 300 will be described. It should be noted that the AT-cut lid wafer, piezoelectric wafer, and base wafer are used in the same manner as the method for manufacturing the piezoelectric device 100. Each process in the method for manufacturing the piezoelectric device 300 is substantially the same as each process described in the method for manufacturing the piezoelectric device 100. The following description will focus on the differences in each process.

  In the piezoelectric vibrating piece forming step, as shown in FIG. 6A, the piezoelectric wafer AW2 has a recess 161 formed in a region where the plurality of piezoelectric vibrating pieces 130 are adjacent to each other so as to correspond to the scribe lines SL1 and SL2. (Recess forming step). The concave portions 161 are each formed in a cross shape, and the width (length in the Z-axis direction) D3 of the portion extending in the X-axis direction is wider than the width L1 of the scribe line SL1, and the portion extending in the Z-axis direction is The width (length in the X-axis direction) D4 is wider than the width L2 of the scribe line SL2. In addition, the process of forming the recessed part 161 is performed simultaneously or separately with the thinning process with respect to the vibration part 131 similarly to 1st Embodiment. The recess forming step is not limited to being performed by etching, and may be performed by mechanical cutting or the like.

In addition, the bonding process, the conductive film forming process, and the cutting process are completed through the same processes as in the first embodiment, and the piezoelectric device 300 is completed.
As described above, since the scribe lines SL1 and SL2 pass through the recess 161, even when the piezoelectric vibrating piece 330 is chipped during dicing, cracks and chips are stopped by the step portion 139a (recess 161), and the inside of the piezoelectric device 300 is The progress of chipping in the direction is suppressed. Therefore, damage to the extraction electrode 137b is prevented, and a highly reliable piezoelectric device can be provided. Further, since the concave portion 161 is formed in a small region on the back surface of the piezoelectric wafer AW2, a decrease in rigidity of the piezoelectric wafer AW2 is small, and cracking of the piezoelectric wafer AW2 can be suppressed in a bonding process or the like.

<Fourth embodiment>
(Configuration of piezoelectric device 400)
Next, a piezoelectric device 400 according to the fourth embodiment will be described. In the following description, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified. 7A is a plan view in which a part of the piezoelectric device 400 is enlarged, and the enlarged part is a part corresponding to the region S in FIG. Further, FIG. 7A shows the lid portion through like the FIG. 2A.

  As shown in FIGS. 7A and 7B, the piezoelectric device 400 includes a lid part 110, a piezoelectric vibrating piece 430, and a base part 120. The lid part 110 and the base part 120 are the same as those used in the piezoelectric device 100 according to the first embodiment. Further, in the piezoelectric vibrating piece 430, the vibration unit 131, the coupling unit 133, the penetration unit 134, and the excitation electrodes 135 and 136 (not shown) are the same as those of the piezoelectric device 100 of the first embodiment.

  In the piezoelectric vibrating piece 430, a step portion 139 b is formed at a corner portion on the back surface of the frame portion 132. As shown in FIG. 7A, the step portion 139b has a rectangular shape that is smaller than the castellation 123 region by a length W1 in the + X-axis direction and a length W2 in the + Z-axis direction, as viewed from the Y-axis direction. Is formed. In addition, the thickness of the frame part 132 in the step part 139b is formed in the same thickness as the vibration part 131 (refer FIG. 1) similarly to the step part 139 of 1st Embodiment.

  On the piezoelectric vibrating piece 430, an extraction electrode 437 electrically connected to the excitation electrode 135 is formed. An extraction electrode 437 a extracted from the excitation electrode 135 is formed on the surface (+ Y side surface) of the frame portion 132. An extraction electrode 437 b electrically connected to the extraction electrode 437 a is formed on the back surface (the surface on the −Y side) of the frame portion 132 via an extraction electrode 437 c formed on the inner surface of the frame portion 132. . The extraction electrodes 437a and 437c are substantially the same as the extraction electrodes 137a and 137c of the first embodiment. The extraction electrode 437b includes a portion corresponding to the castellation 123, and is formed in a rectangular shape over the step portion 139b. However, the extraction electrode 437b is disposed at a position separated from the end portion 132a of the frame portion 132, as shown in FIG. Although not shown, the extraction electrode (corresponding to the extraction electrode 138 in the first embodiment) arranged diagonally to the extraction electrode 437b on the back surface of the frame portion 132 is similarly formed in a rectangular shape over the step portion 139b. Is done.

  As shown in FIG. 7B, the end of the bonding material 143 reaches the stepped portion 139b, and a conductive film 451 is formed so as to cover the end of the bonding material 143. The conductive film 451 is formed together with the external electrode 450 formed on the back surface of the lid portion 120, and electrically connects the external electrode 450 and the extraction electrode 437b.

  Thus, according to the fourth embodiment, since the extraction electrode 437b is formed up to the step portion 139b, the conductive film 451 can be connected to the extraction electrode 437b even if the bonding material 143 reaches the step portion 139b. A poor electrical connection can be avoided. Further, since the bonding material 143 protruding from the castellation 123 is stopped by the step portion 139b, the extraction electrode 437b formed on the step portion 139b and the conductive film 451 can be reliably connected. In addition, since the step portion 139b is small, the joint surface with the base portion 120 can be widened, the reliability of the seal with the base portion 120 can be improved, and the rigidity of the entire piezoelectric device 400 can be ensured.

(Method for Manufacturing Piezoelectric Device 400)
Next, a method for manufacturing the piezoelectric device 400 will be described. It should be noted that the AT-cut lid wafer, piezoelectric wafer, and base wafer are used in the same manner as the method for manufacturing the piezoelectric device 100. Each process in the method for manufacturing the piezoelectric device 400 is substantially the same as each process described in the method for manufacturing the piezoelectric device 100. The following description will focus on the differences in each process.

  In the piezoelectric vibrating piece forming step, the extraction electrode 437b is formed in a rectangular shape over the step portion 139b on the back surface of the frame portion 132 (see FIG. 7A). However, the extraction electrode 437 b is formed in a state of being separated from the end portion 132 a of the frame portion 132. The extraction electrodes 437 a and 437 c are formed in the same manner as the extraction electrodes 137 a and 137 c in the piezoelectric device 100. In the piezoelectric wafer, an opening for forming the step portion 139b is formed. For example, the opening is formed in an arrangement as shown in FIG. The step of forming the recess is performed at the same time as or separately from the thinning step for the vibrating portion 131 as in the first embodiment. The recess forming step is not limited to being performed by etching, and may be performed by mechanical cutting or the like.

  In the bonding step, the base wafer is bonded to the back surface of the piezoelectric wafer via the bonding material 143 in a vacuum atmosphere. At this time, the bonding material 143 protrudes from between the piezoelectric wafer and the base wafer, but is stopped by the recess formed in the piezoelectric wafer and does not enter the recess (that is, the step portion 139b).

  In the conductive film forming step, the external electrode 450 is formed on the back surface of the base wafer, and the side including the side surface of the opening (see the opening 170 formed in the base wafer BW in FIG. 3B) is bonded. A conductive film 451 is formed to the concave portion together with the end portion of the material 143. Note that the connection between the extraction electrode 437b and the conductive film 451 is made in the recess (the subsequent step 139b). In addition, the outer peripheral edge of the extraction electrode 437b is covered with the conductive film 451 in the recess.

  In the cutting step, dicing is performed along the scribe line, as in the method for manufacturing the piezoelectric device 100 according to the first embodiment. Since the scribe line is set in the recess (see FIG. 2), the bonding material 143 and the conductive film 451 are separated from the scribe line, and the conductive film 451 is not cut by dicing. The piezoelectric device 400 is completed by this cutting process.

  As described above, even when the bonding material 143 protrudes between the piezoelectric wafer and the base wafer, the bonding material 143 is stopped by the concave portion, and the conductive film 451 covering the bonding material 143 is prevented from protruding to the scribe line. Accordingly, the conductive film 451 is not inadvertently cut in the cutting step, and generation of defective products can be prevented. In addition, since the recess for forming the stepped portion 139b is formed in a small region on the back surface of the piezoelectric wafer, the rigidity of the piezoelectric wafer is hardly lowered, and cracking of the piezoelectric wafer can be suppressed in the bonding process.

  The first to fourth embodiments have been described above, but the present invention is not limited to the above description, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the castellation (notch portion) 123 is formed at the corner portion of the base portion 120, but instead, it may be provided at the side portion of the base portion 120. In this case, the stepped portion is formed on the outer peripheral side portion on the back surface of the frame portion 132 of the piezoelectric vibrating piece 130 so as to correspond to the castellation.

  In the above-described embodiment, a crystal resonator (piezoelectric resonator) is shown as the piezoelectric device, but an oscillator may be used. In the case of an oscillator, an IC or the like is mounted on the base portion 120, and the extraction electrode 137a of the piezoelectric vibrating piece 130 and the external electrode 150 of the base portion 120 are connected to the IC, respectively. In the above-described embodiment, a quartz crystal vibrating piece is used as the piezoelectric vibrating piece 130. Alternatively, a piezoelectric vibrating piece formed of lithium tantalate, lithium niobate, or the like may be used. Further, although the quartz material is used for the lid portion 110 and the base portion 120, glass, ceramics, or the like may be used instead.

AW1, AW2 ... piezoelectric wafer BW ... base wafer SL1, SL2 ... scribe line 100, 200, 300, 400 ... piezoelectric device 110 ... lid part 120 ... base part 123 ... castation (notch part)
130, 230, 330, 430 ... piezoelectric vibrating piece
131 ... Vibrating part 132 ... Frame part 132a ... End part 133 ... Connecting part 134 ... Through hole 135, 136 ... Excitation electrode 137, 137a, 137b, 137c, 138, 237, 237a, 237b, 237c, 437, 437a, 437b, 437c: Extraction electrode 139, 139a, 139b ... Stepped portions 140, 141, 142, 143 ... Bonding materials 150, 150a, 250, 350, 450 ... External electrodes 151, 151a, 251, 351, 451 ... Conductive films 160, 161 ... Recess 170 ... Opening

Claims (8)

A piezoelectric vibrating piece having a frame part surrounding the vibration part, and having an extraction electrode electrically connected to an excitation electrode provided in the vibration part on a back surface of the frame part;
A base portion that is bonded to the back surface of the piezoelectric vibrating piece via a bonding material and is provided with a notch corresponding to the extraction electrode;
A piezoelectric device in which a conductive film is formed through the notch so as to connect from the external electrode on the back surface of the base portion to the extraction electrode,
The piezoelectric vibrating piece is a piezoelectric device in which a step portion is formed on the back surface side corresponding to the notch portion, which is an end portion of the frame portion.   The piezoelectric device according to claim 1, wherein the step portion is formed over the entire outer periphery of the frame portion.   The piezoelectric device according to claim 1, wherein the extraction electrode is formed apart from the step portion.   The piezoelectric device according to claim 1, wherein the extraction electrode is formed up to the step portion, and the extraction electrode and the conductive film are connected at the step portion.   5. The piezoelectric device according to claim 4, wherein the bonding material is disposed so as to extend to the stepped portion. A plurality of piezoelectric vibrating reeds having a vibrating part including an excitation electrode and a frame part surrounding the vibrating part are formed on the piezoelectric wafer, and an extraction electrode electrically connected to the excitation electrode is formed on the back surface of the frame part. A piezoelectric vibrating piece forming step to be formed;
A base portion forming step in which a plurality of base portions corresponding to the piezoelectric vibrating reed are formed on a base wafer, and an opening is formed in a portion corresponding to the extraction electrode between adjacent base portions;
A bonding step in which the base wafer is bonded to the back surface of the piezoelectric wafer via a bonding material;
A conductive film forming step in which a conductive film connected to the extraction electrode is formed from a part of the back surface of the base portion through the inner surface of the opening;
A cutting step in which individual piezoelectric devices are formed by cutting the piezoelectric wafer and the base wafer along a scribe line set including a part of the opening. There,
The piezoelectric vibrating reed forming step includes a recess on the back surface of the piezoelectric wafer that includes an area that is an end of the frame and is exposed from the opening of the base wafer, and that has a width wider than the width of the scribe line. A method of manufacturing a piezoelectric device including a step of forming a recess.   The method for manufacturing a piezoelectric device according to claim 6, wherein, in the recess forming step, the recess is formed in a lattice shape along the piezoelectric vibrating piece formed on the piezoelectric wafer. The piezoelectric vibrating piece forming step includes a thinning step of thinning the vibrating portion formed on the piezoelectric wafer, and the concave portion forming step is performed simultaneously with the thinning step. Device manufacturing method.

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