JP4752863B2 - Piezoelectric substrate, piezoelectric vibration element, piezoelectric vibrator, piezoelectric oscillator, piezoelectric substrate wafer, and method for manufacturing piezoelectric substrate wafer - Google Patents

Description

  The present invention relates to a piezoelectric substrate having a structure in which an ultrathin vibrating portion is integrally surrounded by a thick annular portion, a piezoelectric vibrating element in which a conductive pattern such as an excitation electrode is formed on the piezoelectric substrate, and a piezoelectric vibrating element in a package. Regarding the improvement of the hermetically sealed piezoelectric vibrator, and further the piezoelectric oscillator and piezoelectric substrate wafer using this piezoelectric vibrator, a recess is formed by etching on the surface of the piezoelectric substrate made of an anisotropic piezoelectric crystal material. In this way, when the vibrating part is formed, by using the etching residue (slow slope) generated on the inner wall of the annular part, the technology and quality to realize the optimum shape corresponding to the miniaturization of the piezoelectric substrate are maintained. The present invention relates to a technique for improving mass productivity in batch processing. Furthermore, the present invention provides a processing method suitable for finely adjusting the thickness of the vibration portion on the bottom surface of the recess after forming a plurality of recesses on the piezoelectric substrate wafer at once, and in a limited narrow piezoelectric substrate. The present invention relates to a technique for securing a vibration part having the widest possible area.

[First Conventional Example]
A surface mount type piezoelectric device having a structure in which a piezoelectric vibration element is hermetically sealed in a package such as a crystal resonator is used as a reference frequency generation source in communication equipment such as a mobile phone and a pager, and electronic equipment such as a computer. Although used as a filter or the like, the piezoelectric devices are also required to be miniaturized in response to the miniaturization of these various devices.
In addition, a piezoelectric oscillator as a surface-mounting piezoelectric device has a recess in a state where a piezoelectric vibration element and a circuit component constituting an oscillation circuit are housed in a recess formed on an upper surface of a package body made of, for example, ceramic. The opening is sealed with a metal lid.
Conventionally, as a piezoelectric vibration element used in the piezoelectric device as described above, a concave portion is formed by excavating a part of one side surface of a piezoelectric substrate so as to cope with a high frequency, and the bottom surface is formed as a thin vibration unit. And a piezoelectric substrate having a structure in which the periphery of the vibrating portion is integrally surrounded by a thick annular portion, and an input / output electrode and a ground electrode formed on both the front and back surfaces of the vibrating portion, respectively. Is known (Japanese Patent Laid-Open No. 9-55635).

FIGS. 9A and 9B are a perspective view and a cross-sectional view showing a configuration of an AT-cut quartz crystal vibration element as an example of such a piezoelectric vibration element. The crystal resonator element 100 includes a crystal substrate 101 made of an AT-cut crystal as an anisotropic piezoelectric crystal material, excitation electrodes 110 formed on both main surfaces of the crystal substrate, and leads extending from the excitation electrodes 110, respectively. An electrode 111 and a connection pad 112 at the end of each lead electrode are provided. The quartz substrate 101 is formed by forming a recess 102 on one main surface of a rectangular flat plate-like substrate body that is long in the x-axis direction, thereby forming an ultrathin vibrating portion 103 on the inner bottom surface of the recess 102. And a configuration in which the outer peripheral edge of the vibrating portion 103 is integrally held by a thick annular portion 104. One side 104 </ b> A located in the x-axis direction of the annular portion 104 is formed to extend over a predetermined length in the x-axis direction to form an overhang portion 105. Each lead electrode 111 is drawn out on one surface of the overhang portion 105, and the connection pad 112 is located at the end of each lead electrode 111.
The reason why the AT-cut quartz crystal substrate 101 is thus elongated in the x-axis direction is that the wave propagation speed in the x-axis direction during excitation is about 1.2 times the wave propagation speed in the z-axis direction. Therefore, it has become customary to adopt an x-axis long structure that is long in the x-axis direction.
When chemical etching is employed as a method for forming the recessed portion 102 on the quartz substrate 101, the annular portion 104 positioned in the z-axis direction when the etching is finished due to the characteristics of quartz as an anisotropic crystal material. On the inner wall, gentle gentle slopes 104a and 104b having small inclination angles θ as etching residues are formed.
FIG. 9C is a cross-sectional view showing a state in which the crystal resonator element 100 having the above-described configuration is mounted in a surface mounting package 120, and the connection of the crystal resonator element 100 with the recessed portion 102 facing downward. The pad 112 is electrically and mechanically fixed on the pad 121 disposed on the inner bottom surface of the package 120 via the conductive adhesive 122. The upper opening of the package 120 is hermetically sealed with a metal lid 123.

By the way, when the crystal substrate 101 (or the crystal resonator element 100) as described above is produced by batch processing using a large-area piezoelectric substrate wafer, the arrangement of the crystal resonator element pieces 100 is laid out as shown in FIG. The That is, on the wafer 130, a plurality of linear dicing grooves (divided grooves) 131 that cross in the vertical and horizontal directions are formed in a grid pattern in advance, and rectangular regions formed between the grooves become individual crystal substrates 101. When etching is performed using a required etchant in a state in which a mask (resist film) that exposes only the quartz substrate surface corresponding to the recess 102 is coated on the wafer 130, the etching direction corresponds to a crystal direction with a slow etching rate as shown in the figure. On the inner wall in the z-axis direction, gentle gentle slopes 104a and 104b are formed as etching residues. Thereafter, the excitation electrode 110, the lead electrode 111, the connection pad 112, and the like are formed in each individual region by a method such as vapor deposition, and then cut along the dicing groove 131 to complete the crystal resonator element 100 as an individual piece. To do.
By the way, the vertical and horizontal dimensions of a quartz crystal substrate housed in an ultra-small package having a vertical and horizontal dimension of 2.5 × 2.0 mm are less than 1.3 × 0.9 mm, and it is inevitable to further reduce the size. On the other hand, when batch processing using the wafer 130 is performed, in order to increase the number of crystal substrates that can be collected from one wafer and increase the mass productivity thereof, the intervals between the crystal substrate pieces are made close to each other to increase the density. However, when producing an ultra-miniaturized quartz substrate as described above, the interval w between the dicing groove 131 and the three outer peripheral edges of the recessed portion 102 becomes extremely narrow as shown in FIG. It will be difficult to secure the annular portion 104 having a sufficient width and sufficient strength later. For this reason, when it cut | disconnects along the dicing groove | channel 131 by division means, such as a dicing blade, it became easy to form a crack in the cyclic | annular part 104 and the vibration part 103, and there existed a problem that productivity fell significantly.

Further, as shown in FIG. 9A, the lead electrodes 111 respectively extending from the excitation electrodes 110 formed on both the front and back surfaces of the vibrating portion 103 have one side 104A of the annular portion 104 positioned in the x-axis direction having a steep inclination. Therefore, there is a problem that the conductive pattern is easily disconnected at corners that are bent at a steep angle.
Further, as shown in FIG. 9C, the connection pad 112 is formed on the overhanging portion 105 that is continuous with the side 104 </ b> A having a steep inner wall slope, and is connected to the pad 121 on the bottom surface of the package by the conductive adhesive 122. As a result, the entire crystal resonator element is supported in a cantilevered state, but in this case, the distance from the position where the conductive adhesive 122 is adhered to the vibrating portion 103 is shortened, and therefore, due to the weight of the crystal resonator element. Stress is likely to be applied to the vibration part 103, distortion occurs in the vibration part, and causes a resonance frequency fluctuation.

[Second Conventional Example]
Next, FIGS. 11A and 11B are a cross-sectional view and a cross-sectional view taken along the line AA of the surface-mount type crystal resonator according to another conventional example, and the crystal resonator element 100 is cut into the recess of the package 120. It has a configuration in which it is hermetically sealed with a metal lid 123 while being held and supported. Two connection pads 112a and 112b are formed on both the front and back surfaces of the protruding portion 105 of the quartz substrate 101, respectively. In this case, the connection pad 112a facing the inner bottom surface of the package is easily electrically and mechanically connected to the corresponding pad 121a and the conductive adhesive 122, but the other connection pad 112b is connected to the quartz substrate. Since it is located on the flat surface side, in order to connect with the pad 121b provided in the recess of the corresponding package, it is necessary to pour adhesive twice. In the second time of the adhesive, the first adhesive is applied between the pad 121b and the lower surface of the quartz substrate, and then the upper connection pad 112b and the first adhesive are connected to each other. A second adhesive application is performed.
However, when the conductive adhesive 122 is deposited twice, a part of the adhesive protrudes on the upper connection pad 112b, and in order to avoid contact between the adhesive and the lower surface of the metal lid 123, It is necessary to set the height of the outer peripheral wall large. As a result, the low profile of the package is hindered, resulting in a result contrary to the demand for downsizing.
In order to eliminate such problems, conventionally, as shown in FIG. 11 (c), a concave notch 140 having a conductor film on the entire inner wall at the substrate edge corresponding to the edge of the connection pad 112b on the upper surface side ( 140a, 140b), and the conductive film on the inner wall of the concave notch 140b is electrically connected to the upper surface side connection pad 112b, while the lower side of the corresponding conductive film on the lower surface of the substrate is also connected to the conductive film on the inner wall of the concave notch 140b. A connection pad 112b ′ is formed. For this reason, by connecting the lower connection pad 112b ′ and the pad 121b on the inner bottom surface of the package with the conductive adhesive 122, electrical conduction between the upper connection pad 112b and the pad 121b by one adhesive application. Can be secured.

In forming the concave notch as described above, as shown in FIG. 11 (d), the quartz substrate piece 101 is small from both the front and back sides by chemical etching using a mask (resist film) on the piezoelectric substrate wafer 130 having a large area. After the excavation of the recess and the formation of the through hole 140H by connecting both small recesses, a conductive film is applied to the inner wall of the through hole, and a procedure of dividing along the dicing groove 131 is performed. However, for example, the diameter (width) of each through hole 140H formed in the connection pad 112b on the ultra-small crystal resonator element having a vertical and horizontal dimension of 1.3 × 0.9 mm or less must be a minute dimension on the order of μm. Since it cannot be obtained, etching defects that do not completely communicate between the two small recesses formed from the front and back both sides are likely to occur frequently. On the other hand, as long as the through hole 140H constituting the concave notch 140 is formed within a narrow area of the connection pad 112b having a limited area, there is a limit to increasing the diameter thereof. In particular, it is difficult to form two through holes along one end edge of a very small piezoelectric substrate.
Accordingly, a solution to the problem of a decrease in the yield of the micro crystal resonator element due to poor formation of the through hole when the through hole 140H constituting the concave notch 140 is formed on the large-area piezoelectric substrate wafer 130 by chemical etching. Has been strongly desired.
The reason why the two concave cutouts 140 are provided on the edge of the quartz substrate 101 is that, as described above, with respect to one concave cutout 140b, the connection pad 112b above the lower connection pad 112b and the pad 121b on the package side. This is for the purpose of providing the upper connection pad 112a ′, which is electrically connected to the lower connection pad 112a, on the upper surface of the quartz substrate. As a result, when measuring the characteristics such as the resonance frequency of the individual crystal resonator elements formed on the wafer 130, the two connection pads 112b and 112a ′ arranged on the upper surface of the crystal substrate, or the lower surface side Measurement can be performed with the probe pins of the measuring instrument in contact with the two connection pads 112a and 112b ′ from the same direction. This is because it is most efficient to perform measurement by bringing the probe pin into contact with two connection pads located on the same surface on the substrate.
In addition, as a direction for mounting the crystal resonator element 100 in the package, the concave portion side is not always directed downward as shown in FIG. 11A, and the concave portion side is also mounted upward. For this reason, if two connection pads are arranged on both sides of the substrate, one crystal resonator element 100 can be mounted in the package in any orientation.

[Third conventional example]
Next, when recesses are formed by chemical etching in each piece region on a sheet-like piezoelectric substrate wafer having a configuration in which a plurality of piezoelectric substrates are arranged in rows and columns, the ultrathin portions of the bottoms of all the recesses are formed. It is difficult to make the thickness of the vibration portion uniform. For this reason, conventionally, the depth of each concave portion, in other words, the variation in the thickness of the vibrating portion in each concave portion is measured in advance, and the thickness of the vibrating portion that does not reach the specified thickness is finely adjusted. In order to do this, adjustment work using an etching solution is performed individually for each recess.
FIGS. 12A and 12B are diagrams for explaining a conventional fine adjustment method for each recessed portion, and a mask (resist film) (not shown) is coated on one main surface of the piezoelectric substrate wafer 130. FIG. In this state, only the wafer surface exposed from each opening of the mask is etched in a lump, thereby forming the recess 102 in a lump. In such a batch operation by etching, since the thickness of the vibrating portion 103 located at the bottom of each concave portion 102 is not constant, the thickness of the vibrating portion 103 in each concave portion 102 is measured in advance, Next, individual etching is performed in a state where a guide mask having a grid-like configuration as indicated by reference numeral 150 is disposed in close contact with the side surface of the recessed portion of the wafer 130. That is, the guide mask 150 has a configuration in which openings 152 having a rectangular shape or other shape are formed on a resin thin plate at a predetermined pitch, for example, and the planar shape of the recessed portion 102 is formed between the partition portions 151 intersecting in a grid pattern. A plurality of aligned openings 152 are formed. The guide mask 150 is fixed on the wafer 130 in a state where the partition portion 151 is in close contact with the peripheral plane of the recessed portion 102 as shown in FIG. In this state, an appropriate amount of the etching solution 155 is sequentially put into each concave portion with a predetermined time difference in order from the concave portion having the vibration portion having the maximum thickness to the concave portion having the thin thickness vibration portion. Fill one by one. Then, when the thickness of all the vibrating parts is etched to a constant value, the wafer is cleaned in a lump to remove the etching solution.

By the way, the size of the opening 152 of the guide mask 150 is limited to miniaturization due to limitations in machining technology, and the size as shown in FIG. 12B is the limit. Therefore, for example, as shown in FIG. 12C, in order to finely adjust the thickness of the vibrating portion of the concave portion 102 having a small size formed on the wafer 130 made of a further small size piezoelectric substrate piece by individual etching. Therefore, it is necessary to use the guide mask 150 manufactured for the concave portion having a large size as it is. Alternatively, in order to reliably drop the etching solution into the recessed portion, an opening 152 having a size as small as shown in FIG. Then, as shown in the drawing, the recessed portion 102 and the dicing groove 131 are exposed in the opening 152 between the partition portions 151. In such a state, when the opening 152 is filled with an etching solution, the etching solution that protrudes from the recessed portion penetrates into the dicing groove 131 and etches the portion that is not desired to be etched, resulting in a decrease in strength of the portion. Come on. Furthermore, as shown in (d), the surface tension of the etching solution 155 may cause the etching solution filled in the recessed portion 102 not to adhere to the bottom of the recessed portion, thereby forming an unfilled void 156, In this case, the individual etching becomes defective.
In order to eliminate the variation in the depth of the concave portions formed on the wafer as described above, when the individual etching is performed for each concave portion, the etching is performed due to the restriction on the opening size of the guide mask 150 to be used. There is a possibility that etching is performed on unnecessary portions, or etching on the vibrating portion becomes defective.

[Fourth Conventional Example]
Next, FIG. 13 is a cross-sectional view showing a configuration of an AT-cut quartz crystal substrate as an example of a piezoelectric substrate. The quartz substrate 101 is made of AT-cut quartz as an anisotropic piezoelectric crystal material, and concave portions 102a and 102b having point symmetrical shapes are formed on both main surfaces of the quartz substrate 101 by chemical etching. . That is, the quartz substrate 101 is formed by etching the recesses 102a and 102b with the masks (resist) 160 covered on both main surfaces of the rectangular flat plate main body, thereby forming the recesses 102a and 102b. An ultra-thin vibrating portion 103 is positioned on a common inner bottom surface, and the outer peripheral edge of the vibrating portion 103 is integrally held by a thick annular portion 104. Due to the difference in etching rate between the z-axis direction and the x-axis direction, the inner walls 104a and 104b of the two sides located in the z-axis direction of each annular portion 104 are gentler than the other inner walls located on the x-axis direction side. It is an inclined surface. Moreover, the inclination angles of the inner walls 104a and 104b are different.
However, when the mask 160 having the same opening shape is covered and etched in a state in which the mask 160 is aligned at the same position on both sides of the quartz substrate 101, the z-axis direction of the recesses 102a and 102b is shown as shown in the figure. The inner walls 104a and 104b on the side have a symmetrical positional relationship, and the positions of the edges 102a ′ and 102b ′ of the inner bottom surfaces of the recessed portions 102a and 102b do not match. Thus, since the positions of the edges 102a ′ and 102b ′ of the inner bottom surfaces of the concave portions 102a and 102b are shifted in the z-axis direction, the inner bottom surfaces do not match, and the area of the vibrating portion 103 is reduced, which is effective. The thin region (effective vibration region) becomes narrow. For this reason, there has been a problem that the characteristics of the quartz resonator element manufactured by forming electrodes or the like on the quartz substrate are deteriorated. In particular, when the piezoelectric substrate is miniaturized, such a problem becomes serious.
Japanese Patent Laid-Open No. 9-55635

The present invention has been made in view of the above, and the first problem corresponding to the first conventional example is to form a recess by etching on the surface of a piezoelectric substrate made of an anisotropic piezoelectric crystal material. When mass-producing ultra-small piezoelectric substrates with vibrating parts formed by batch processing using a large-area piezoelectric substrate wafer, ensure sufficient thickness of the annular part surrounding the recessed part to crack during splitting Is to prevent. Another object of the present invention is to prevent disconnection by wiring a conductive pattern via an inner wall of the annular portion that avoids a steeply inclined surface formed by etching residues generated on the inner wall of the annular portion. Furthermore, when the piezoelectric vibration element is supported in a cantilever state in the package, the stress due to the weight of the quartz crystal vibration element is applied to the vibration part by separating the distance from the cantilever support part to the vibration part as much as possible. Another challenge is to prevent the addition. As described above, the first problem is to realize an optimum shape corresponding to the miniaturization of the piezoelectric substrate in the piezoelectric substrate including the ultrathin vibrating portion and the thick annular portion surrounding the vibrating portion. It is in.
A second problem corresponding to the second conventional example is that two connection pads are formed on each of the front and back surfaces of each substrate piece on a large-area piezoelectric substrate wafer obtained by connecting the piezoelectric substrate pieces in a sheet shape. When forming a through hole (concave notch) as an electrical connection means for chemical etching, a through hole formation failure that occurs due to restrictions on an increase in the opening size of the through hole, This is to prevent the productivity from being lowered.

A third problem corresponding to the third conventional example occurs when a plurality of concave portions are collectively formed on a piezoelectric substrate wafer, and then the thickness of the vibration portion in each concave portion is individually adjusted by etching with a time difference. In order to solve various problems, there is an attempt to perform fine adjustment of the vibration part by performing etching from the flat surface side instead of the adjustment work of filling the recess with the etching solution.
A fourth problem corresponding to the fourth conventional example is a piezoelectric substrate in which a thin vibrating portion is formed by forming concave portions on both main surfaces of a piezoelectric substrate made of an anisotropic crystal material by chemical etching. An object of the present invention is to solve the problem that an effective vibration region is narrowly formed because the positions of both concave portions disposed opposite to each other through the vibration portion are shifted in one crystal axis direction.

In order to solve the above-described problem, the first embodiment of the present invention has a recessed portion that is recessed from one main surface toward the other main surface opposite to the main surface, and the bottom of the recessed portion. a vibration portion provided to, a piezoelectric substrate with an annular portion of the thicker than the thickness of the vibrating portion surrounding integrally with the outer peripheral edge of the vibrating portion, the other main surface, A plate thickness obtained by finely adjusting the plate thickness of the vibrating portion by etching so as to be flat across the annular portion and the vibrating portion so that a stepped portion remains at one edge of the outer peripheral edge of the annular portion. It is characterized by a piezoelectric substrate which is a fine adjustment processing part.
According to a second aspect of the present invention, there is provided an excitation electrode formed on both surfaces of the vibrating portion of the piezoelectric substrate according to the first embodiment, and a lead electrode extending from each excitation electrode to one longitudinal edge of the piezoelectric substrate. And a piezoelectric vibration element including connection pads respectively connected to the lead electrodes.
According to a third aspect of the present invention, there is provided a piezoelectric vibrator in which one end portion on one end side in the longitudinal direction of the piezoelectric substrate constituting the piezoelectric vibration element according to the second embodiment is bonded and held in a surface mounting package. Features.
According to a fourth aspect of the present invention, there is provided a surface-mount type piezoelectric oscillator including at least the piezoelectric vibrator described in the third aspect and an oscillation circuit.
According to a fifth aspect of the present invention, there is provided a piezoelectric substrate wafer in which a plurality of piezoelectric substrates according to the first embodiment are connected in a sheet form.
According to a sixth aspect of the present invention, the piezoelectric substrate wafer includes two parallel substrates for obtaining the piezoelectric substrate pieces by cutting the piezoelectric substrate wafer into a thick portion between the piezoelectric substrate pieces. There is a dividing groove, and when the flat substrate surface of the piezoelectric substrate wafer is etched between the dividing grooves to finely adjust the thickness of the vibrating portion of the piezoelectric substrate piece, the adjacent vibrating portion is affected. The piezoelectric substrate wafer according to the fifth embodiment is provided with a space not to give the resistance.
Further, according to the seventh aspect of the present invention, the thickness of the vibrating portion is made fine by etching the side surface opposite to the recessed portion of each piezoelectric substrate piece on the piezoelectric substrate wafer according to the fifth or sixth embodiment. The adjusted plate thickness fine-adjustment processing section is configured so that each of the openings of the guide mask is in contact with the opposite side surface of the piezoelectric substrate wafer with a grid-shaped guide mask in which a plurality of openings larger than the recessed portion are arranged. It is characterized by a method of manufacturing a piezoelectric substrate wafer that is processed and formed by filling an etching solution into the portion.
Application Example 1 A piezoelectric substrate according to this application example includes a thin vibrating portion and a thick annular portion that integrally surrounds the outer peripheral edge of the vibrating portion, thereby at least one main surface side. In the piezoelectric substrate having a concave portion formed of an anisotropic piezoelectric crystal, the annular portion has an inner wall on one crystal axis direction side and the other crystal axis orthogonal to this The piezoelectric substrate has an inclination angle that is gentler than the inner wall on the direction side, and the outer dimension of the piezoelectric substrate is such that the substrate length in the one crystal axis direction is longer than the substrate length in the other crystal axis direction. And
When an anisotropic piezoelectric material is processed into a plate-like piezoelectric substrate along two orthogonal crystal axes, if a recess is formed on the surface of this piezoelectric substrate by chemical etching, the etching rate in the direction of one crystal axis is increased. Since the etching rate is faster than the other etching rate, the inner wall on the crystal axis direction side where the etching rate is slow among the inner walls of the annular portion constituting the recessed portion becomes a gently inclined surface (slowly inclined surface). In the present invention, since one side having such a gentle slope is extended and formed as an overhanging portion of the inner wall of the annular portion, the piezoelectric substrate (piezoelectric vibration element) is obtained by batch processing using a large-area piezoelectric substrate wafer. When mass-producing, it is possible to secure a sufficient width between the dicing grooves and other divided grooves that divide the individual pieces and the recessed portions while maintaining the same area. it can. Therefore, no cracks are generated in the annular portion when cutting along the dividing groove. As a result, an optimum shape corresponding to the miniaturization of the piezoelectric substrate can be realized in the piezoelectric substrate including the ultrathin vibrating portion and the thick annular portion surrounding the vibrating portion.
Application Example 2 A piezoelectric substrate according to this application example includes a thin vibrating portion and a thick annular portion that integrally surrounds the outer peripheral edge of the vibrating portion, thereby at least one main surface side. In the piezoelectric substrate made of AT-cut quartz having a concave portion formed therein, the outer dimensions of the piezoelectric substrate made of AT-cut quartz are longer in the z′-axis direction than in the x-axis.
When an AT-cut quartz substrate is employed as the piezoelectric substrate, it is preferable that the substrate length along the z-axis direction is longer than the substrate length along the x-axis direction.

Application Example 3 A piezoelectric vibration element according to this application example includes an excitation electrode formed opposite to both surfaces of the vibration portion of the piezoelectric substrate, a lead electrode extending from each excitation electrode to one longitudinal edge of the piezoelectric substrate, Each lead electrode and a connection pad connected to each lead electrode, wherein the lead electrode extending from the excitation electrode on the recessed portion side is drawn out through the inner wall of the annular portion having the gentle inclination angle. .
According to this, disconnection can be prevented by wiring the lead electrode (conductive pattern) via the annular portion inner wall that avoids the steeply inclined surface formed by the etching residue generated on the annular portion inner wall.
Application Example 4 A piezoelectric vibration element according to this application example is characterized in that one end in the longitudinal direction of a piezoelectric substrate constituting the piezoelectric vibration element is bonded and held in a cantilevered state in a surface mounting package.
According to this, when the piezoelectric vibration element is supported in a cantilever state in the package, the stress due to the weight of the crystal vibration element is reduced by separating the distance from the cantilever support part to the vibration part as much as possible. It can prevent adding to a vibration part.
Application Example 5 A piezoelectric oscillator according to this application example includes at least the piezoelectric vibrator and an oscillation circuit.

Application Example 6 A piezoelectric substrate according to this application example includes a thin vibrating portion and a thick annular portion that integrally surrounds the outer peripheral edge of the vibrating portion, thereby at least one main surface side. A piezoelectric substrate having a concave portion formed therein, and having a projecting portion formed by extending one side of the annular portion, at least one penetrating the front and back sides of the piezoelectric substrate at the end edge of the projecting portion. It is characterized by having a concave notch.
When connecting pads that are conductively connected to the two excitation electrodes on the front and back sides on the same surface of the overhanging portion of the piezoelectric substrate, connection with the pads on the bottom surface inside the package is achieved by applying a conductive adhesive only once. It is possible to prevent an increase in the size of the outer peripheral wall of the package. On the other hand, when two connection pads are arranged on both the front and back sides of the overhanging portion, the direction of the front and back when the piezoelectric vibration element is mounted in the package can be arbitrarily selected. It is necessary to place two concave notches on the end edge and to make the connection pads arranged two on each of the front and back surfaces conductive. At this time, if two concave cutouts are arranged within the width of the end edge of the overhanging portion as in the prior art, the width of each concave cutout is minimized, and the piezoelectric substrate wafer is etched through both the front and back sides. There is an increased risk that the recessed notch (through hole) cannot be formed. Therefore, in the present invention, it is possible to prevent the formation of a concave notch due to defective etching by forming a long through hole extending over adjacent substrate piece regions on a wafer.
Application Example 7 The piezoelectric substrate according to this application example is characterized in that the concave notches are arranged one by one at both corners of the end edge of the overhanging portion.
As described above, it is effective to form the through-hole extending over a region adjacent to both end corners of the terminal edge of the protruding portion of one piezoelectric substrate on the piezoelectric substrate wafer.
Application Example 8 A piezoelectric vibration element according to this application example includes an excitation electrode formed to face both surfaces of the vibration portion of the piezoelectric substrate, a lead electrode extending from each excitation electrode to a terminal edge of the overhang portion, One of the lead electrodes is routed to the opposite side surface through the concave notch and is electrically connected to the connection pad formed on the opposite side surface.
Two connection pads can be juxtaposed on the same surface of the overhang part, or two connection pads can be juxtaposed on both the front and back surfaces of the overhang part.

Application Example 9 In the piezoelectric vibrator according to this application example, two connection pads juxtaposed on the same surface of the protruding portion of the piezoelectric substrate constituting the piezoelectric vibration element are connected to each pad in the surface mounting package. Each of these is characterized in that it is adhered and held with a conductive adhesive.
Application Example 10 A surface-mount piezoelectric oscillator according to this application example includes at least the piezoelectric vibrator and an oscillation circuit.
Application Example 11 A piezoelectric substrate wafer according to this application example has a piezoelectric substrate wafer structure in which a plurality of the piezoelectric substrates are connected in a sheet shape, and the concave notch is formed on the wafer. Are formed on both piezoelectric substrate pieces at the same time by forming a through hole extending between the adjacent piezoelectric substrate pieces.
When the through hole is formed so as to straddle between the adjacent individual regions on the wafer, the length of the through hole can be increased. As a result, when the small recesses are simultaneously formed by etching from both the front and back sides of the piezoelectric substrate, the through holes can be completed by reliably communicating the small recesses. Alternatively, the number of concave cutouts provided on the edge of one piezoelectric substrate is not necessarily two, and may be one long hole provided in the width of the end edge of the overhanging portion. In this case, an elongated through hole may be formed in the width of the end edge of the overhang portion of the piezoelectric substrate piece on the wafer.
[Application Example 12] A piezoelectric substrate wafer according to this application example is a piezoelectric substrate wafer in which a plurality of the piezoelectric substrates are connected in a sheet shape, and an unused area is arranged between the adjacent piezoelectric substrate pieces. The concave notch is formed on the piezoelectric substrate piece by forming a through hole extending between one piezoelectric substrate piece and an adjacent unused area.
When the piezoelectric substrate pieces are directly arranged on both sides of the piezoelectric substrate piece, the excitation electrode, the lead electrode, and the connection pad are formed, and then the probe pin is brought into contact with each connection pad and the piezoelectric vibration element piece is When the characteristic is measured, the contact pressure of the probe pin brings about the fluctuation of the resonance frequency, and the accurate measurement becomes impossible. In view of this, an unused area (dummy area) is disposed on both sides of the piezoelectric substrate, and the connection pad is formed on the unused area. If the measurement is performed by bringing the probe pin into contact with the connection pad on the unused area, the adverse effect due to the contact pressure of the probe pin is eliminated. In particular, if the dividing groove is formed on the substrate surface between the piezoelectric substrate piece and the unused area, the adverse effect due to the contact pressure is further reduced.

Application Example 13 A piezoelectric substrate according to this application example includes the thin vibrating portion and a thick annular portion that integrally surrounds an outer peripheral edge of the vibrating portion, thereby at least one main surface. A piezoelectric substrate having a concave portion formed on a side thereof is characterized in that a plate thickness fine adjustment processing portion of a vibrating portion is provided on a substrate surface opposite to the concave portion.
After etching a plurality of recesses on one main surface of the piezoelectric wafer at a predetermined pitch, a guide mask is attached on the substrate surface in order to finely adjust the thickness of the vibration part in the recess. In the state, it has been conventionally performed to fill each recessed portion with an etching solution. However, when the size of the recessed portion is reduced to an ultra-small size, other portions are provided via the dividing grooves formed between the individual pieces of the etching solution. Inconveniences such as a decrease in the substrate strength due to etching into the etching unnecessary portions.
In this application example, the guide mask is brought into contact with the flat surface side of the wafer, and an etching solution is individually filled in the opening of the guide mask to finely adjust the thickness of the vibrating portion. As a result, the thickness adjustment of the vibration part in the piezoelectric substrate in which the size of the recessed part is miniaturized can be ensured.
[Application Example 14] A piezoelectric vibration element according to this application example includes an excitation electrode formed to face both surfaces of the vibration portion of the piezoelectric substrate, a lead electrode extending from each excitation electrode to one longitudinal edge of the piezoelectric substrate, And a connection pad connected to each lead electrode.
[Application Example 15] A piezoelectric vibrator according to this application example is characterized in that one end of a piezoelectric substrate constituting the piezoelectric vibration element is bonded and held in a cantilevered state in a surface mounting package.
Application Example 16 A piezoelectric oscillator according to this application example includes at least the piezoelectric vibrator and an oscillation circuit.
Application Example 17 A piezoelectric substrate wafer according to this application example is characterized in that a plurality of the piezoelectric substrates are connected in a sheet form.
[Application Example 18] The piezoelectric substrate wafer according to this application example is provided with a configuration in which the piezoelectric substrate wafer has a dead space interposed between two pieces of piezoelectric substrate through two parallel dividing grooves. Features.
By disposing a dummy region that becomes a sufficient dead space between the piezoelectric substrate pieces, it is possible to avoid an adverse effect due to the etching solution during the thickness adjustment operation from the flat surface side of the wafer.

[Application Example 19] In the method of manufacturing a piezoelectric substrate wafer according to this application example, the plate thickness fine adjustment processing portion of the vibration portion formed on the side surface opposite to the concave portion of each piezoelectric substrate piece on the piezoelectric substrate wafer has a concave portion. In a state where a grid-shaped guide mask in which a plurality of openings larger than the portion are arranged is in contact with the opposite side surface of the piezoelectric substrate wafer, it is formed by filling each opening of the guide mask with an etching solution. It is characterized by that.
Application Example 20 A piezoelectric substrate according to this application example includes the thin vibrating portion and a thick annular portion that integrally surrounds the outer peripheral edge of the vibrating portion. A piezoelectric substrate having a structure in which a recessed portion is formed, each of which is made of an anisotropic piezoelectric crystal, and each of the recessed portions has an inner wall on one crystal axis direction side and another crystal perpendicular thereto It has a gentler inclination angle than the inner wall on the axial direction side, and is configured so that the positions of the edges on the one crystal axial direction side of the inner bottom surfaces of the respective recessed portions coincide with each other. It is characterized by being.
When forming concave portions by etching using masks of the same shape from both sides of a piezoelectric substrate made of an anisotropic piezoelectric crystal material, if the positions of the openings of the masks on the front and back sides match, It has a point-symmetric shape, and the positional relationship between the edges of the inner bottom surface of each recess (particularly, the edge on the axial direction side where the etching rate is slow) does not match. For this reason, the area of a thin vibration part becomes narrow.
In this application example , the positions of the edges of the opening portions of the front and back masks (particularly, the edge on the axial direction side where the etching rate is slow) are shifted in advance, so that the edges of the two recessed portions after the etching The position was matched. For this reason, the area of a vibration part can be maximized and a highly reliable piezoelectric substrate, piezoelectric vibrator, etc. can be obtained.

Application Example 21 A piezoelectric substrate according to this application example is characterized in that the piezoelectric substrate is an AT cut crystal.
[Application Example 22] A piezoelectric vibration element according to this application example includes an excitation electrode formed to face both surfaces of the vibration portion of the piezoelectric substrate, a lead electrode extending from each excitation electrode to one longitudinal edge of the piezoelectric substrate, And a connection pad connected to each lead electrode.
Application Example 23 A piezoelectric vibrator according to this application example is characterized in that one end portion in the longitudinal direction of a piezoelectric substrate constituting the piezoelectric vibration element is bonded and held in a surface mount package in a cantilever state.
Application Example 24 A surface-mount type piezoelectric oscillator according to this application example includes at least the piezoelectric vibrator and an oscillation circuit.
Application Example 25 A method for manufacturing a piezoelectric substrate according to this application example includes the thin vibrating portion and a thick annular portion that integrally surrounds the outer peripheral edge of the vibrating portion. A piezoelectric substrate having a structure in which concave portions are formed on the surface, each of which is made of an anisotropic piezoelectric crystal, and each of the concave portions has an inner wall on one crystal axis direction side that is orthogonal to the other. In a method of manufacturing a piezoelectric substrate having a gentler inclination angle than an inner wall on the crystal axis direction side, a mask covering a mask for excavating and forming each of the concave portions on both main surfaces of a flat plate-like piezoelectric substrate And a recess forming step of forming recesses on both principal surfaces of the piezoelectric substrate exposed in the openings of the respective masks by etching the piezoelectric substrate covering each of the masks. , The position of each of the masks, the one crystal axis direction Shifting the result, characterized in that said align your edges of the respective inner bottom surface of the concave portion.
Application Example 26 In the piezoelectric substrate manufacturing method according to this application example, the piezoelectric substrate is a piezoelectric substrate wafer in which a plurality of piezoelectric substrate pieces are connected in a sheet shape.

As described above , according to the first aspect of the present invention, an ultra-small piezoelectric substrate in which a vibrating portion is formed by forming a recessed portion by etching on a surface of a piezoelectric substrate made of an anisotropic piezoelectric crystal material is obtained. When mass production is performed by batch processing using a piezoelectric substrate wafer, a sufficient thickness of the annular portion surrounding the recessed portion can be secured to prevent cracking during division. Also, disconnection can be prevented by wiring the conductive pattern via a gentle slope that avoids the steep slope formed by the inner wall of the annular portion. Furthermore, when the piezoelectric vibration element is supported in a cantilever state in the package, the stress due to the weight of the quartz crystal vibration element is applied to the vibration part by separating the distance from the cantilever support part to the vibration part as much as possible. Another challenge is to prevent the addition. As described above, the first problem is to realize an optimum shape corresponding to the miniaturization of the piezoelectric substrate in the piezoelectric substrate including the ultrathin vibrating portion and the thick annular portion surrounding the vibrating portion. It is in.
According to the second aspect of the present invention, on the piezoelectric substrate wafer, through holes (concave notches) are chemically formed as electrical connection means for forming two connection pads on each of the front and back surfaces of each substrate piece. When forming by etching, it is possible to prevent a through-hole formation failure caused by the restriction on the enlargement of the opening size of the through-hole and a decrease in productivity due to the formation.
According to the third aspect of the present invention, after forming a plurality of recesses on the piezoelectric substrate wafer at once, various problems that occur when the thickness of the vibration part in each recess is individually adjusted by time-dependent etching. In order to solve the problem, the thickness of each vibration part can be finely adjusted by performing etching from the flat surface side instead of the adjustment work of filling the recess with the etching solution.
According to the fourth invention, in the piezoelectric substrate in which the thin vibrating portion is formed by forming the concave portions on both main surfaces of the piezoelectric substrate made of an anisotropic crystal material by chemical etching, the piezoelectric substrate is opposed to the piezoelectric substrate through the vibrating portion. Since the positions of the arranged concave and convex portions are shifted in the direction of one crystal axis, it is possible to solve the problem that an effective vibration region is formed narrowly.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
[Embodiment corresponding to the first conventional example]
1A and 1B are an external perspective view and a plan view of a crystal resonator element 1 made of an AT-cut crystal as an example of a piezoelectric resonator element according to an embodiment of the present invention.
The crystal resonator element 1 includes a crystal substrate 2 made of AT cut crystal as an anisotropic piezoelectric crystal material, excitation electrodes 10a and 10b formed on both main surfaces of the crystal substrate 2, and each excitation electrode 10a. 10b, lead electrodes 11a and 11b respectively extending from 10b, and connection pads 12a and 12b at the ends of the lead electrodes.
The quartz substrate 2 is formed by etching the recessed portion 3 on one main surface of a rectangular flat plate-like substrate main body elongated in the z-axis direction, so that the ultrathin vibrating portion 4 is formed on the inner bottom surface of the recessed portion 3. And a configuration in which the outer peripheral edge of the vibrating portion 4 is integrally held by the thick annular portion 5. One side 5 </ b> A located in the z-axis direction of the annular portion 5 is formed by extending a predetermined length in the z-axis direction to form a flat plate-like protruding portion 6. The lead electrodes 11a and 11b are drawn out on one surface of the overhang portion 6, and the connection pads 12a and 12b are located at the ends of the lead electrodes 11a and 11b.
One characteristic feature of the crystal resonator element 1 according to this embodiment that is different from the crystal resonator element according to the conventional example is that the crystal substrate 2 has a long z-axis rectangular shape that is long in the z-axis direction. The width and strength of the portion 5 are ensured sufficiently large. Therefore, the gentle slope 5a having the gentlest inclination angle is located on the overhanging portion 6 side. In addition, the lead electrode 11a drawn from the excitation electrode 10a formed on the inner bottom surface on the recessed portion side of the vibration portion 4 can be wired along the gentlest gentle slope 5a. Furthermore, when the crystal resonator element is cantilevered in the package, the distance between the support portion and the vibration portion can be made as long as possible.

When the recess 3 is formed on the main surface of the quartz substrate 2, only the portion corresponding to the recess 3 is exposed, the other portion is concealed with a mask, and etching is performed using a required etchant. At this time, among the four inner walls of the recessed portion 3, each of the inner walls 5a and 5b positioned in the z-axis direction has a gentle slope as an etching residue than the inner walls positioned in the x-axis direction. Is done. In the present embodiment, the crystal substrate 2 is laid out so that the protruding portion 6 is positioned in the z-axis direction of the recessed portion 3 by utilizing this phenomenon during etching. For this reason, when the crystal substrate pieces are arranged on the wafer 30 via the dividing grooves 31 such as dicing grooves, the horizontally long state is obtained as shown in FIG. At this time, the area of each quartz substrate is the same as that of the conventional quartz substrate shown in FIG.
That is, in the present invention, the area and shape of the quartz substrate itself are set to be equivalent to those of the conventional example shown in FIG. 10, while the longitudinal direction of the quartz substrate is configured to coincide with the z-axis direction. Therefore, it is possible to ensure a sufficiently large interval w between the three end edges of the recessed portion 3 and each of the divided grooves 31, and the thickness of the annular portion 5 can be increased. It is possible to prevent cracks from occurring during the cutting division along the line.
Further, when the distance between the lead electrodes 11a and 11b and the distance between the connection pads 12a and 12b are too close, there is a possibility that electrical interference occurs and adversely affects the characteristics of the crystal resonator element. When the lead electrode 11a on the concave portion side is formed along the gentle slope 5a, the lead electrode 11b on the flat surface side is wired on the side surface of the concave portion through a path as far as possible from the lead electrode 11a.
The connection pad 12a connected to the lead electrode 11a on the recessed portion side is disposed near one end edge in the width direction (x-axis direction) of the overhang portion 6, while the lead electrode is drawn from the flat surface side to the recessed portion side. The other connection pads 12b are separated from the connection pads 12a as much as possible by shifting the position 11b toward the other end in the width direction.

Next, FIG. 2 is a cross-sectional view showing a state where the crystal resonator element 1 shown in FIG. 1 is mounted in a surface mounting package 20 and hermetically stored. The package 20 includes a package body 21 having a recess and a metal lid 26 that closes the opening of the recess of the package body 21. The package body 21 includes an external electrode 22 formed on the outer bottom surface, and an internal electrode 23 formed on the inner bottom surface of the recess and electrically connected to the external electrode 22. A conductive adhesive 25 is provided on the internal electrode 23. The crystal oscillator 1 is supported in a cantilever state by electrically and mechanically connecting the connection pads 12 to each other.
At this time, the connection part (support part) between the connection pad 12 and the internal electrode 23 and the vibration part 4 are connected to each other via the gentle slope 5 a having the gentlest inclination angle among the inner walls of the recessed part 3. It has become. That is, the connecting portion made of the adhesive is moved away from the vibrating portion 4 by using the gentle slope 5a having a gentle slope, the stress applied to the vibrating portion is relaxed by the cantilever support structure, and the vibrating portion is less likely to be distorted. ing.

Next, FIG. 3 shows an example in which the crystal resonator element 1 of the present invention is applied to a surface-mount type crystal oscillator. The crystal oscillator 40 includes, for example, an internal portion on a step where the crystal resonator element 1 is provided in the package body 21. The connection pad 12 is fixed and cantilevered by the conductive adhesive 25 on the electrode 23 and a circuit component 41 constituting an oscillation circuit or the like is mounted on the pad provided on the inner bottom surface of the package body 21. The recess of the package body 21 is sealed with a metal lid 26.
In the above embodiment, the AT-cut quartz is exemplified as the anisotropic piezoelectric crystal material. However, this is only an example, and the present invention (the same applies to other embodiments) can be applied to all anisotropic piezoelectric crystal materials. Is possible. That is, it has a configuration in which a concave portion is formed on at least one main surface side by including a thin vibrating portion and a thick annular portion that integrally surrounds the outer peripheral edge of the vibrating portion, and is anisotropic The piezoelectric substrate structure of the present invention can be applied to a piezoelectric substrate made of a conductive piezoelectric crystal material. In this case, there is a gentle slope with the smallest inclination angle among the inner walls of the annular portion. The length of the substrate along the direction to be set is set longer than the length of the substrate along the direction orthogonal to the direction in which the gentle slope exists.
By configuring in this way, it is possible to achieve effects such as thickening the annular part, preventing disconnection of the lead electrode, and preventing distortion at the vibration part when mounted in a cantilevered state in the package. It becomes.

[Embodiment corresponding to second conventional example]
4 (a), 4 (b), and 4 (c) are a perspective view of a crystal resonator element (crystal substrate) according to an embodiment of the present invention corresponding to a second conventional example, a cross-sectional view of a state mounted on a package, and It is a structure explanatory view of a wafer. In this embodiment, an example in which a quartz substrate is used as the piezoelectric material is shown, but this is only an example, and the present invention can be applied to all types of piezoelectric materials.
The crystal resonator element 1 includes a crystal substrate 2 made of an AT-cut crystal as a piezoelectric crystal material, excitation electrodes 10a and 10b formed on both main surfaces of the crystal substrate 2, and leads extending from the excitation electrodes 10a and 10b, respectively. Electrodes 11a, 11b and connection pads 12a, 12a ′, 12b, 12b ′ at the end portions of the lead electrodes are provided.
The quartz substrate 2 includes the thin vibrating portion 4 and the thick annular portion 5 that integrally surrounds the outer peripheral edge of the vibrating portion, thereby forming the concave portion 3 on at least one main surface side. The piezoelectric substrate having the configuration includes an overhanging portion 6 formed by extending one side 5A of the annular portion 5. At the end edge 6 a of the overhanging portion 6, at least one concave notch 7 a, 7 b that penetrates the both sides of the quartz substrate 2 is provided. In this example, concave notches 7a and 7b are provided at both ends of the end edge 6a, that is, both corners of the overhanging portion 6, and the connection pads 12a, 12a ′, 12b are provided on the inner walls of the concave notches 7a, 7b. , 12b ′ is formed.

The connection pad 12a connected to the lead electrode 11a extending from the excitation electrode 10a provided on the recessed portion 3 side is electrically connected to the connection pad 12a ′ provided on the flat surface side via the conductor film on the inner wall of the concave notch 7a. On the other hand, the connection pad 12b connected to the lead electrode 11b extending from the excitation electrode 10b provided on the flat surface side of the substrate is connected to the connection pad 12b ′ provided on the recessed portion side through the conductor film on the inner wall of the concave notch 7b. Conduct.
Alternatively, only one concave cutout may be provided, and only one of the lead electrodes may be routed to the opposite side surface, and the second connection pad may be disposed on the opposite side surface of the substrate.
As described above, in the present embodiment, any one of the lead electrodes 11a and 11b extending from the excitation electrodes 10a and 10b formed to face both surfaces of the vibration part 4 of the piezoelectric substrate 2 to the terminal edge 6a of the projecting part 6 is provided. Since it is routed through the conductor film in the concave notch to the opposite side surface and the connection pad is arranged on the opposite side surface, the crystal resonator element with the recessed portion side facing down in the package 20 as shown in FIG. 1 is mounted, the two connection pads 12a and 12b ′ are positioned on the overhanging portion 6 on the recessed portion side, and each of the pads 23a on the package side can be formed by applying a conductive adhesive only once. As a result, the conductive adhesive does not protrude on the flat surface side of the substrate. For this reason, it is not necessary to increase the height of the outer peripheral wall of the package 20 in accordance with the protruding amount of the conductive adhesive, and a reduction in the height of the package can be realized.
Further, by arranging two connection pads 12a and 12b ′ and connection pads 12b and 12b ′ on both sides of the overhanging portion 6, the crystal resonator element 1 is oriented in an arbitrary direction in the package. Can be installed.

Next, a procedure for mass production of the piezoelectric substrate 2 or the crystal resonator element 1 of the present invention by batch processing using a large-area crystal substrate wafer (piezoelectric substrate wafer) 30 will be described with reference to FIG. (For reference, the state in which the conductor pattern is formed only in a part of FIG. 4C is shown.) That is, in this embodiment, the divided grooves 31 are formed between the divided grooves by forming them vertically and horizontally. The rectangular space to be formed is a quartz substrate piece, and the recessed portion 3 and the through hole 7H constituting the recessed notches 7a and 7b are formed by a chemical etching method using a required etchant and mask. The characteristic configuration of this wafer is that the through holes 7H constituting the concave cutouts are formed across two substrate pieces adjacent to each other on the left and right, so that both end corners of the terminal edge 6a of the overhanging portion 6 are formed. The concave cutouts 7a and 7b are located respectively.
The through hole 7H is formed by simultaneously forming small recesses from the same location on both sides of the substrate and penetrating both small recesses as mentioned in the description of the conventional example. And when the diameter of a small recess is too small, it has the malfunction which a penetration defect tends to produce.

As described above, in this embodiment, the concave notches 7a and 7b are simultaneously formed on both crystal substrate pieces by forming the through holes 7H extending between the crystal substrate pieces adjacent to each other on the wafer 30. At this time, since the through hole 7H has a large dimension in which two concave cutouts are connected, the small recesses are simultaneously etched at the corresponding positions on both the front and back sides of the substrate so that the small recesses communicate with each other. When forming the through-hole, the possibility of occurrence of poor penetration is greatly reduced.
Thereafter, the excitation electrodes 10a and 10b, the lead electrodes 11a and 11b, and the connection pads 12a, 12a ′, 12b, and 12b ′ are formed on the front and back of each substrate piece by an arbitrary method such as vapor deposition and sputtering using a required mask. A conductive film is formed in each of the concave cutouts 7a and 7b.
After the formation of these conductor patterns, the probe pins of the measuring device are brought into contact with the connection pads 12a ′, 12b on the flat surface side or the connection pads 12a, 12b ′ on the recessed portion side, thereby allowing each crystal resonator element An operation of measuring the characteristics such as the resonance frequency of the piece is performed, and after the adjustment operation for each piece is performed based on the measurement result, cutting along the dividing groove 31 is performed.

By the way, after forming a crystal oscillation element piece by forming a conductor pattern such as an excitation electrode on each crystal substrate piece on the quartz substrate wafer 30, the characteristics of each crystal oscillation element piece using a probe pin are measured. In this case, if the pieces are directly adjacent to each other at the nearest position as shown in FIG. 4C, 2 provided on one piece of crystal vibrating element to be measured. The probe pins are brought into contact with the two connection pads 12a and 12b ′ inside the left and right dividing grooves 31. However, since the distance between the position where the probe pin abuts and the vibrating portion 4 is a close distance of 0.5 mm or less, even if the probe pin is a slight pressure abutting against the substrate surface via each connection pad, There is a possibility that the resonance frequency of the vibration unit 4 may be affected, which is a factor that makes accurate measurement difficult.
FIG. 5 is a plan view showing a main configuration of a piezoelectric substrate wafer according to an embodiment for solving such a problem.
A characteristic configuration of the piezoelectric substrate wafer 30 is that dead spaces 50 as regions not forming individual pieces are arranged on both the left and right sides of the crystal resonator element 1 (piezoelectric substrate 2) via the dividing grooves 31. 50, the dummy connection pads 51 that are electrically connected to the connection pads 12a, 12b ′ or 12a ′, 12b provided on the crystal resonator element piece are formed. Each dummy connection pad 51 is electrically connected to each connection pad on both the front and back surfaces at adjacent positions via a conductor film on the inner surface of the through hole 7H (concave notches 7a and 7b).

When measuring the characteristics of each vibration element piece 1 on the piezoelectric substrate wafer 30 having the above configuration, probe pins of a measuring device (not shown) are directly placed on the connection pads 12a, 12b ′ or 12a ′, 12b. It is possible to perform measurement in a state where the probe pin is in contact with the dummy connection pad 51 arranged adjacent to each connection pad via the dividing groove 31 without making contact.
In this case, the transmission of the stress generated by bringing the probe pin into contact with the dummy connection pad 51 is blocked by the dividing groove 31, and the influence on the vibration part 4 of the crystal vibrating element piece 1 is reduced and accurate. Measurement is possible.
In the illustrated example, the area of the dead space 50 is illustrated equivalent to that of the adjacent piezoelectric substrate 2, but this is only an example, and the area of the dead space 50 may be further narrowed.
4 and 5, the through holes 7H are formed between the adjacent individual regions or between the individual regions and the dead space, so that the end of the overhanging portion 6 of one piezoelectric substrate 2 is formed. In total, two concave cutouts 7a and 7b are formed at both ends of the edge 6a, but the number of concave cutouts may be one.

FIGS. 6A and 6B are a main part configuration diagram of a piezoelectric substrate wafer according to another embodiment, and a perspective view of a crystal vibration element piece. The piezoelectric substrate wafer 30 has a configuration in which a long hole-like through hole 7H is formed through the terminal edge 6a of the projecting portion 6 of the piezoelectric substrate piece 2, and a divided conductor film 7C is formed on the inner wall of the through hole 7H. By forming, the connection pads 12a and 12a 'on both the front and back sides and the connection pads 12b and 12b' are electrically connected.
Excitation electrodes 10a and 10b, lead electrodes 11a and 11b, connection pads 12a, 12a′12b and 12b ′, and divided conductor film 7C are formed, and each connection pad or dummy connection pad 51 (see FIG. 5) is used. After the measurement with the probe pin, the individual pieces as shown in FIG. 6B are obtained by cutting and dividing along the dividing grooves 31. At this time, the portion corresponding to the through hole 7 </ b> H becomes the concave notch 7 by cutting along the trajectory of the dividing groove 31. The divided conductor films 7C on the inner wall of the concave notch 7 are separated from each other.
According to this, since one through hole may be formed for each piece, the configuration of the mask used at the time of etching is simplified, the manufacturing cost is reduced, and the mass productivity is increased.
In addition, by forming the excitation electrodes on both surfaces of the vibration part of the piezoelectric substrate having the above-described configuration, respectively, and forming the lead electrodes extending from the respective excitation electrodes to the terminal edge of the projecting part and the connection pads, respectively. A piezoelectric vibration element is completed.
In addition, by bonding and holding two connection pads juxtaposed on the same surface of the projecting portion of the piezoelectric substrate constituting the piezoelectric vibration element, with each pad in the surface mounting package by a conductive adhesive. The piezoelectric vibrator is completed.
Furthermore, a surface mount piezoelectric oscillator is completed by assembling circuit components constituting the oscillation circuit to the package constituting the piezoelectric vibrator as described above.

[Embodiment corresponding to third conventional example]
FIGS. 7A and 7B are explanatory views of an embodiment corresponding to the third conventional example. In this embodiment, the guide mask 60 in which the size and pitch of the opening 61 (partition 62) are determined in advance is shown. Then, the flat surface side of the vibration part 4 of each piezoelectric substrate piece 2 exposed to the flat surface side of the piezoelectric substrate wafer 30 and exposed in each opening 61 is individually etched.
That is, as mentioned in the description of the prior art, there is a limit to minimizing the size and pitch of the opening 61 of the guide mask 60 due to limitations in machining technology. For this reason, if the thickness of the vibrating part 4 in the recessed part 3 that is smaller than the opening 61 of the minimum size is individually adjusted, the guide mask 60 must be used. However, there are too many disadvantages for the individual etching in which the guide mask 60 is brought into contact with the recessed portion side as in the prior art.
Therefore, in the present invention, the arrangement interval of the piezoelectric substrate pieces 2 on the wafer 30 is set in advance according to the opening size and pitch of the openings 61 of the guide mask 60, and the thick wall between the piezoelectric substrate pieces 2 is set. Two parallel dividing grooves 31 are formed on the part. The thickness of the vibration part 4 in each recessed part 3 is in a measured state in advance, and the time required for etching the vibration part 4 having different thicknesses to a uniform thickness is calculated in advance.
Then, the guide mask 60 is additionally fixed to the flat surface side of the wafer 30 so that each vibration part 4 is positioned at the center of all the openings 61 of the guide mask 60. In this state, an etching solution is filled in each recess through each opening 61 in a predetermined order. At this time, the etching solution is filled in order from the recessed portion having the thick vibrating portion 4 to the recessed portion having the thin vibrating portion, and the thickness of all the vibrating portions is the specified thickness. When the thickness is reduced to the thickness, the etching solution is cleaned at once.

As a result, as shown in FIG. 7C, a plate thickness fine adjustment processing portion 65 is formed as a fine recess having a larger area than the recess on the wafer flat surface exposed in the opening 61. It becomes a state. Reference numeral 50 denotes a dummy area arranged between the pieces.
As described above, in this embodiment, the guide mask is brought into contact with the flat surface side of the wafer, and the etching solution is filled into the recesses that require fine adjustment of the thickness of the vibration part with a time difference, and is collectively cleaned at the end of the etching. As a result, there is no adverse effect of the etching solution on the recessed portion side of the wafer, and the etching solution does not permeate to other places through the dividing grooves 31 to cause problems. In addition, of course, problems such as defective etching due to the fact that the etching liquid filled in the recessed portion cannot be brought into close contact with the inner wall of the recessed portion due to the surface tension thereof do not occur.
In addition, by arranging two split grooves 31 in parallel between the piezoelectric substrate pieces, the thick portion located between the two split grooves becomes a dead space. By sufficiently securing the width of this dead space, it is possible to avoid the possibility that the etching solution filled in a certain opening 61 adversely affects the adjacent piezoelectric substrate pieces. In this way, by finely adjusting the thickness of the vibrating portion 4 in the recessed portion, the wafer 30 is cut and divided along the dividing groove 31 to finely adjust the thickness of the vibrating portion 4 on the substrate surface opposite to the recessed portion 3. The piezoelectric substrate piece 2 having the portion 65 can be obtained.
Excitation electrodes are respectively formed on both surfaces of the vibrating portion 4 of the piezoelectric substrate 2 having such a configuration, and lead electrodes extending from the respective excitation electrodes to one end in the longitudinal direction of the piezoelectric substrate are connected to the respective lead electrodes. The piezoelectric vibration element is completed by forming the connection pads by vapor deposition or the like.

Further, one end of a piezoelectric substrate constituting such a piezoelectric vibration element is bonded and held in a cantilevered state in a surface mounting package, and the package is hermetically sealed with a lid, thereby completing a piezoelectric vibrator.
Further, the surface mount type piezoelectric oscillator is completed by assembling and integrating the circuit components constituting the oscillation circuit at appropriate positions of the package constituting the piezoelectric vibrator.
[Embodiment corresponding to the fourth conventional example]
Next, FIG. 8A is a cross-sectional view of a piezoelectric substrate according to an embodiment of the present invention corresponding to the fourth conventional example.
Here, a piezoelectric substrate made of AT-cut quartz is shown as an example of an anisotropic piezoelectric crystal material.
The quartz crystal substrate 2 includes a thin vibrating portion 4 and a thick annular portion 5 that integrally surrounds the outer peripheral edge of the vibrating portion 4, thereby providing concave portions 3 a and 3 b on both main surfaces, respectively. It has a formed configuration. Each recess 3a, 3b has an inner wall 5a, 5b on one crystal axis direction (z-axis direction) side having a gentler inclination angle than an inner wall on the other crystal axis direction (x-axis direction) side orthogonal thereto. I have. And it is comprised so that the position of edge 3a ', 3b' of each inner bottom face of each recessed part 3a, 3b may correspond. For this reason, the effective region area of the vibration part 4 can be maximized.

When the recesses 3a and 3b of the quartz crystal substrate 2 having such a structure are manufactured by chemical etching, as shown in FIG. 8B, each mask (resist) 70a for covering the front and back of the substrate, respectively, The positions of the z-axis direction edges of the openings 70a ′ and 70b ′ of 70b are shifted by a predetermined distance L. The predetermined distance L may be set so that the positions of the edges 3a ′ and 3b ′ of the inner bottom surfaces of the recessed portions 3a and 3b coincide with each other when etching is performed.
It should be noted that an excitation electrode formed opposite to both surfaces of the vibrating portion 4 of the piezoelectric substrate 2 having the above-described configuration, a lead electrode extending from each excitation electrode to one longitudinal edge of the piezoelectric substrate, and a connection to each lead electrode By forming the connection pads, the piezoelectric vibration element is completed.
Further, a piezoelectric vibrator is constructed by adhering and holding one end portion of the piezoelectric substrate 2 constituting the piezoelectric vibration element in a surface mounting package in a cantilever state.
Further, a surface-mount type piezoelectric oscillator is constructed by incorporating a circuit component constituting an oscillation circuit into a package constituting the piezoelectric vibrator.
In the manufacture of the piezoelectric substrate as shown in FIG. 8, a mask forming step for covering the masks 70a and 70b for excavating and forming the respective concave portions on both main surfaces of the plate-like piezoelectric substrate 2; By performing etching on the piezoelectric substrate coated with each mask, a recessed portion forming step of forming recessed portions 3a and 3b on both principal surfaces of the piezoelectric substrate exposed in the openings of the respective masks is performed. However, in the mask formation process, the positions of the masks 70a and 70b are shifted in the direction of one crystal axis (z-axis direction), thereby matching the edges 3a ′ and 3b ′ of the inner bottom surfaces of the recessed portions. Let
The piezoelectric substrate 2 may be a piezoelectric substrate wafer in which a plurality of piezoelectric substrate pieces are connected in a sheet shape. In this case, mass production by batch processing is possible.

(A), (b) and (c) are an external perspective view, a plan view, and a main part configuration diagram of a crystal resonator element made of an AT-cut crystal as an example of a piezoelectric resonator element according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a crystal resonator in which the crystal resonator element of FIG. The figure which shows the example which applied the crystal oscillation element of this invention to the surface mount type crystal oscillator. (A), (b) and (c) are perspective views of a crystal resonator element (crystal substrate) according to an embodiment of the present invention corresponding to the second conventional example, a cross-sectional view of a state mounted on a package, and a wafer FIG. The top view which shows the principal part structure of the piezoelectric substrate wafer which concerns on other embodiment of this invention. (A) And (b) is a principal part block diagram of the piezoelectric substrate wafer which concerns on other embodiment, and the perspective view of a crystal vibration element piece. (A) And (b) is explanatory drawing of embodiment corresponding to a 3rd prior art example, (c) is explanatory drawing of a plate | board thickness fine adjustment process part. (A) is sectional drawing of the piezoelectric substrate which concerns on embodiment of this invention corresponding to a 4th prior art example, (b) is sectional drawing of a piezoelectric vibrator. (A) And (b) is the perspective view and sectional drawing which show the structure of the AT cut quartz-crystal vibrating element as an example of the conventional piezoelectric vibrating element, (c) is mounting the quartz-crystal vibrating element in the package for surface mounting Sectional drawing which shows a state. The principal part block diagram of the piezoelectric substrate wafer used when forming the piezoelectric substrate of FIG. (A) And (b) is sectional drawing and AA sectional drawing of the surface mount-type quartz crystal resonator concerning another prior art example, (c) is a perspective view which shows the structure of the concave notch provided in the overhang | projection part termination edge FIG. 4D is a configuration diagram of a main part of the piezoelectric wafer. (A) (b) And (c) is a figure for demonstrating the conventional fine adjustment method for every recessed part, (d) is a figure for demonstrating the fault of the conventional fine adjustment method. Sectional drawing of the conventional piezoelectric substrate provided with the recessed part on both surfaces.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Quartz vibration element (piezoelectric vibration element), 2 Quartz substrate (piezoelectric substrate), 3 Recessed part, 3a, 3b Recessed part, 3a ', 3b' Edge of inner bottom face, 4 Vibration part, 5 Ring part, 5a Slow slope 5b inner wall, 5A side, 6 overhang, 6a end edge, 7, 7a, 7b concave notch, 7H through hole, 10a, 10b excitation electrode, 11a, 11b lead electrode, 12a, 12b connection pad, 12a ′, 12b 'Connection pad, 20 package, 21 package body, 22 external electrode, 23 internal electrode, 25 conductive adhesive, 26 metal lid, 30 crystal substrate wafer (piezoelectric substrate wafer), 31 split groove, 40 crystal oscillator, 41 circuit components , 50 dead space, 51 dummy connection pad, 60 guide mask, 61 opening, 65 plate thickness fine adjustment processing part, 70a, 70b , 70a ', 70b' opening

Claims (7)

Having a recessed portion recessed from one main surface toward the other main surface opposite to the main surface;
A vibrating section is provided at the bottom of the recessed portion, a piezoelectric substrate with an annular portion of the thicker than the thickness of the vibrating portion surrounding integrally with the outer peripheral edge of the vibrating portion,
The other main surface is etched so that a stepped portion remains at one edge of the outer peripheral edge of the annular portion so as to be flat across the annular portion and the vibrating portion. A piezoelectric substrate characterized in that it is a plate thickness fine-adjustment processing part in which the thickness is fine-adjusted.   2. An excitation electrode formed opposite to both surfaces of the vibrating portion of the piezoelectric substrate according to claim 1, a lead electrode extending from each excitation electrode to one longitudinal edge of the piezoelectric substrate, and a connection pad connected to each lead electrode And a piezoelectric vibration element.   3. A piezoelectric vibrator, wherein one end portion on one end side in the longitudinal direction of the piezoelectric substrate constituting the piezoelectric vibration element according to claim 2 is bonded and held in a surface mounting package.   A surface-mounted piezoelectric oscillator comprising at least the piezoelectric vibrator according to claim 3 and an oscillation circuit.   A piezoelectric substrate wafer comprising a plurality of piezoelectric substrates according to claim 1 connected in a sheet form. The piezoelectric substrate wafer is
In the thick part between the piezoelectric substrate pieces, two parallel grooves for cutting the piezoelectric substrate wafer to obtain the piezoelectric substrate pieces are provided,
When the flat substrate surface of the piezoelectric substrate wafer is etched between the divided grooves to finely adjust the thickness of the vibrating portion of the piezoelectric substrate piece, the adjacent vibrating portions are not affected. The piezoelectric substrate wafer according to claim 5, further comprising a space.   The plate thickness fine adjustment processing portion obtained by finely adjusting the plate thickness of the vibrating portion by etching a side surface opposite to the concave portion of each piezoelectric substrate piece on the piezoelectric substrate wafer according to claim 5 or 6 is the concave portion. In a state where a grid-shaped guide mask having a plurality of larger openings arranged in contact with the opposite side surface of the piezoelectric substrate wafer, each opening of the guide mask is filled with an etching solution. A method for manufacturing a piezoelectric substrate wafer, comprising:

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