JP2007184810A - Method for manufacturing piezoelectric vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a crystal vibration chip from being damaged due to discharge during anode bonding and to improve the reliability of the bonding. <P>SOLUTION: A method for manufacturing a crystal vibrator 10 includes steps of: forming a crystal substrate wafer 20 where a plurality of crystal vibrating chips 21 each having vibrating arms 22 and 23 and a frame portion 25 united are arranged; forming an upper substrate wafer 30 having a plurality of upper substrates arranged and being made of glass; forming a lower substrate wafer 40 having a plurality of lower substrates 41 arranged and being made of glass; forming a laminate 1 by anode-bonding the upper substrate wafer 30, crystal substrate ware 20, and lower substrate wafer 40; and cutting the laminate 1 into pieces along cutting lines 2. The step of forming the lower substrate wafer 40 includes a step of forming recesses 50 at intersections of the cutting lines 2 and further includes a step of boring through holes 44 in the recesses 50 in the state where the laminate 1 is formed and a step of forming connection electrodes 47 connected to lower conductive films 26a on internal surfaces of the through holes 44. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a piezoelectric vibrator. Specifically, the present invention relates to a method for manufacturing a piezoelectric vibrator configured by anodically bonding a piezoelectric vibrating piece, an upper substrate, and a lower substrate.

  Conventionally, along with the downsizing and thinning of electronic equipment, piezoelectric vibrators are required to be further downsized and thinned. In general, surface mount type piezoelectric vibrators are packaged with a piezoelectric vibrating piece formed of an insulating material. A sealing structure is widely adopted. As a method for realizing thinning and miniaturization, a method of anodic bonding of the piezoelectric vibrating piece and the upper and lower lids has been proposed as a package manufacturing method. In the anodic bonding process, discharge is caused by applying a high voltage. There is a problem of damaging the piezoelectric vibrating piece and the electrode.

  There has been proposed an example in which such a manufacturing method for preventing the occurrence of discharge in the anodic bonding process is applied to a semiconductor sensor manufacturing method. This manufacturing method is a method for manufacturing a semiconductor sensor comprising a glass pedestal having a through-hole and a silicon substrate having a detection part that is bonded to the glass pedestal and faces the through-hole. After the first step of anodically bonding the silicon wafer and the glass pedestal with the hole sealed (in the state of the recess), and after the anodic bonding step in the first step, the through-hole blocking portion (the bottom of the recess) is removed. It is a manufacturing method of having the 2nd process to perform (for example, refer to patent documents 1).

JP-A-9-101218 (page 3, FIGS. 3 to 6)

  In Patent Document 1, as a countermeasure against discharge in the anodic bonding process, anodic bonding is performed in a state where the pressure introduction hole that should originally be a through hole is sealed, and after the anodic bonding, the sealed portion is processed by a processing means such as polishing. Removed and opened a pressure introduction hole. When a voltage is applied in such a sealed state, it is possible to prevent discharge generated in the through hole.

  However, it is predicted that the glass pedestal is likely to be damaged by the method of removing the blocking portion by polishing and forming the through hole.

  In addition, since polishing is performed after bonding a glass wafer and a silicon wafer having a three-dimensional upper electrode on the surface, it is difficult to stably hold the back surface of the glass base horizontally, and the thickness of the glass base varies. There is a problem such as going out.

  Furthermore, since the opening of the recess is on the bonding surface between the glass pedestal and the silicon wafer, the bonding area is small, and the arrangement balance of the bonding surface may be deteriorated, so that the bonding quality may not be stable.

  An object of the present invention is to solve the above-described problems, and to provide a method for manufacturing a piezoelectric vibrator that can prevent damage to the piezoelectric vibrating piece due to discharge during anodic bonding and can increase the reliability of the bonding. Is to provide.

In the method for manufacturing a piezoelectric vibrator according to the present invention, a plurality of piezoelectric vibrating pieces in which a vibrating arm and a frame portion around the vibrating arm are integrated are arranged, and the first excitation electrode provided on the vibrating arm and the first A lower conductive film that is continuous with the excitation electrode and formed on the lower surface of the frame; a second excitation electrode; an upper conductive film that is continuous with the second excitation electrode and formed on the upper surface of the frame; and the upper conductive film A step of forming a piezoelectric substrate wafer having a lead electrode formed on the lower surface of the frame portion that is continuous with the film, and a plurality of upper substrates having bonding surfaces provided corresponding to the upper surface of the frame portion are disposed. A step of forming an upper substrate wafer made of glass, a step of forming a lower substrate wafer made of glass in which a plurality of lower substrates having a bonding surface provided corresponding to the lower surface of the frame portion are provided, and the upper substrate wafer Bonding surface, frame portion of the piezoelectric substrate wafer, and lower substrate wafer A step of forming a laminated body by anodically bonding the bonding surface, and a step of cutting the laminated body along vertical and horizontal cutting lines to separate the piezoelectric vibrator into pieces, and the lower substrate wafer Forming a recess in the surface of the intersection of the cutting lines, and in the state where the laminate is formed, a step of opening a through hole in the recess, and an inner surface of the through hole Forming a connection electrode connected to the upper conductive film or the extraction electrode.
Here, as the piezoelectric vibrating piece, for example, a quartz vibrating piece can be adopted.

  According to the present invention, in the structure of the piezoelectric vibrator in which the first and second excitation electrodes provided on the piezoelectric vibrating piece are taken out from the through holes provided in the lower substrate, the through holes are subjected to anodic bonding. Since the through hole is opened after anodic bonding with no penetration (recessed state), discharge generated in the through hole during anodic bonding can be suppressed, and damage to the piezoelectric vibrating piece, electrode, etc. due to discharge can be suppressed. Can be prevented.

  In the present invention, it is preferable that the concave portion is formed on the lower surface side of the lower substrate wafer.

  In this way, the bonding surface between the lower substrate wafer and the piezoelectric substrate wafer does not have a concave opening, and the bonding surface is a smooth and uniform surface, so that it is easy to ensure bonding quality. There is an effect like this.

  More preferably, the recess is formed in a tapered shape in which the opening on the lower surface side of the lower substrate wafer is wider than the bottom.

  As described above, through holes are formed in the recesses after anodic bonding, and connection electrodes are formed. As will be described later in detail in the embodiment, the connection electrode is formed by means such as sputtering from the lower surface side of the lower substrate wafer. Therefore, since the opening on the lower surface side is formed in a taper shape wider than the bottom portion, the connection is made from the lower surface of the lower substrate wafer to the depth of the lower conductive film or the extraction electrode in the upper surface direction of the lower substrate wafer. An electrode can be formed.

  Moreover, it is more preferable that the concave portion is formed by a sandblasting process.

  There are many methods for drilling a tapered recess, but sand blasting makes it possible to easily form a desired taper shape by adjusting the abrasive material, particle size, spraying speed, time, etc. Furthermore, since a plurality of recesses can be formed simultaneously in a short time, the production efficiency can be increased.

  In the present invention, it is desirable to form the concave portion on the upper surface side of the lower substrate wafer.

  Thus, even if the concave portion is formed in the upper surface direction of the lower substrate wafer, the through hole is not opened until the anodic bonding is completed (the concave portion state), and the anodic bonding is performed to open the through hole after the anodic bonding. Sometimes, it is possible to prevent the electric discharge generated in the through hole.

  In the present invention, it is more desirable to form the recess by an etching process.

  Although details will be described in an embodiment described later, a space serving as a cavity for accommodating the piezoelectric vibrating piece is formed on the upper surface of the lower substrate wafer by an etching process. This space is formed by the etching process. If it makes it, a recessed part and a space can be formed in the same etching process, and productivity can be improved.

  Moreover, although this recessed part can also be formed by sandblasting etc., the recessed part formed by sandblasting becomes a taper shape. When the concave portion is viewed from the lower surface of the lower substrate wafer, it becomes a reverse taper, and when the connection electrode is formed by sputtering from the lower surface side, it does not reach the lower conductive film or the extraction electrode on the upper surface side of the lower substrate wafer from the lower surface of the lower substrate wafer. It is possible. However, according to the etching, the side surface in the recess can be formed substantially perpendicular to the lower surface of the lower substrate wafer, so that the connection electrode can be formed up to the lower conductive film or the extraction electrode.

  Moreover, it is preferable that the process of opening the through-hole mentioned above is an etching process.

  In this case, the bottom of the concave portion only needs to be removed by etching as compared with the polishing method in which the opening of the through hole as in the prior art described above is used, so that the lower substrate wafer is not damaged and the thickness does not vary. .

  In the present invention, it is more desirable to include a step of filling the inner surface of the connection electrode with a conductive member after the step of forming the connection electrode.

  The connection electrode is formed in the above-described through hole by sputtering or the like. However, when the through hole is deep (the lower substrate wafer is thick), it is rarely formed uniformly to the depth of the lower conductive film or the extraction electrode. Although it is conceivable, the lower conductive film or the upper conductive film and the connection electrode can be more reliably connected by filling the conductive member.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 4 show the structure of the piezoelectric vibrator according to the first embodiment of the present invention, FIGS. 5 to 8 show the method of manufacturing the piezoelectric vibrator according to the first embodiment, and FIGS. 9 and 10 show the second embodiment. FIG. 11 shows a part of the method for manufacturing a piezoelectric vibrator according to the third embodiment. In the present invention, a crystal resonator using a crystal as a piezoelectric resonator will be described as an example.
(Embodiment 1)

  FIG. 1 is a plan view showing a schematic structure of the crystal resonator according to the first embodiment, and FIG. 2 is a cross-sectional view showing the AA section of FIG. FIG. 1 shows a state in which the upper substrate 31 is seen through. 1 and 2, the crystal resonator 10 is configured by integrally laminating an upper substrate 31 and a lower substrate 41 on each of an upper surface and a lower surface of a crystal vibrating piece 21. In the present embodiment, the upper substrate 31 and the lower substrate 41 are preferably made of soda glass having an approximate thermal expansion coefficient in the plane direction of the crystal vibrating piece 21. The upper substrate 31, the crystal vibrating piece 21, and the lower substrate 41 are each anodically bonded in the state of a large-sized wafer to form the laminate 1, and then cut and separated along the cutting line 2, A vibrator 10 is formed.

As shown in FIG. 1, the quartz crystal vibrating piece 21 is a tuning fork type vibrating piece in which vibrating arms 22 and 23 extend from a base 24, and includes a frame portion 25 surrounding the base 24 and the vibrating arms 22 and 23. Are integrally formed. The details of the electrode configuration are shown in FIGS. 3 and 4, and the first and second excitation electrodes 26 and 27 are continuous on the front and back surfaces of the vibrating arms 22 and 23 and the frame portion 25, respectively. A lower conductive film 26a and an upper conductive film 27a are formed.
The upper conductive film 27a communicates with a via hole (contact hole) 28 and is connected to an extraction electrode 27b provided on the lower surface side.

  The upper substrate 31 is formed with a recess 32 so that the vibrating arms 22 and 23 can be vibrated, and the peripheral portion of the recess 32 is a joint surface 33 formed in substantially the same shape as the frame portion 25 of the crystal vibrating piece 21. Yes (dot display area in FIG. 1).

  The lower substrate 41 is provided with a recess 42 so that the vibrating arms 22 and 23 can vibrate in the same manner as the upper substrate 31, and the peripheral portion of the recess 42 is formed in substantially the same shape as the frame portion 25 of the crystal vibrating piece 21. This is the bonded surface 43 (in FIG. 1, a region indicated by dots). In addition, a notch 44a is provided at the outer peripheral corner of the lower substrate 41. On the inner surface (side surface) of the notch 44a, a connection electrode 48 connected to the extraction electrode 27b and a lower conductive film are provided. A connection electrode 47 connected to 26a is formed. The connection electrodes 47 and 48 are provided at two places on the left and right in the drawing, respectively. Further, the connection electrodes 47 and 48 are connected to external electrodes 45 and 46 provided on the lower surface of the lower substrate 41.

  A plurality of crystal vibrating pieces 21 are formed on the crystal substrate wafer 20, an upper substrate 31 is formed on the upper substrate wafer 30, and a plurality of lower substrates 41 are formed on the lower substrate wafer 40. After that, it is cut along the cutting line 2 and separated into crystal units 10. Therefore, the above-described cutout portion 44 a is formed by cutting the through hole 44 provided in the outer peripheral corner portion of the lower substrate 41.

  In the crystal resonator 10 configured as described above, the vibrating arms 22 and 23 are housed in a cavity formed by the recesses 32 of the upper substrate 31 and the recesses 42 of the lower substrate 41 so as to vibrate. The first excitation electrode 26 and the second excitation electrode 27 are connected to the external electrodes 45 and 46, respectively, so that an excitation signal can be input from the external electrodes 45 and 46 and a resonance signal can be output. .

Next, each electrode configuration formed on the crystal vibrating piece 21 will be described with reference to the drawings.
3 shows the upper surface side of the quartz crystal vibrating piece, and FIG. 4 shows the lower surface side. 3 and 4, a first excitation electrode 26 is provided at the top end of the upper surface of the vibrating arm 22 and extends from the outer peripheral surface of the vibrating arm 22 to the upper surface of the base 24 and the center of the upper surface of the vibrating arm 23. ing. Further, a lower conductive film 26 a is formed on the lower surface of the frame portion 25 so as to extend from the side surface of the vibrating arm 22 to the lower surface side.

  A second excitation electrode 27 is provided at the top end of the upper surface of the vibrating arm 23, and extends from the outer peripheral surface of the vibrating arm 23 to the upper surface of the base 24 and the center of the upper surface of the vibrating arm 22. Furthermore, an upper conductive film 27 a is formed on the upper surface of the frame portion 25 so as to extend from the side surface of the vibrating arm 23 to the upper surface side.

  The first excitation electrode 26 and the second excitation electrode 27 are formed so as to be plane symmetric with respect to the upper surfaces of the vibrating arms 22 and 23. The upper conductive film 27a extends to the lower surface side by two via holes 28 formed in the frame portion 25 at the end portion (right end portion in the drawing) of the frame portion 25, and is connected to the extraction electrode 27b. ing. Accordingly, the first excitation electrode 26 and the second excitation electrode 27 extend to the lower surface side of the crystal vibrating piece 21 and are connected to the lower conductive film 26a and the extraction electrode 27b.

  Each electrode is formed in the state of the quartz substrate wafer 20 by first forming the vibrating arms 22 and 23 and the via hole 28 (through hole state) by an etching process and then using a photolithography technique. .

  The first excitation electrode 26, the second excitation electrode 27, the lower conductive film 26a, the upper conductive film 27a, and the extraction electrode 27b described above are formed of Al or an Al alloy, but are made of a material such as Cr, Ti, or Au. One or more kinds of thin films selected from the above may be used, and the connection electrodes 47 and 48 and the external electrodes 45 and 46 can be used by vapor deposition, sputtering or plating of Au / Cr, Ni, Ti or the like.

Next, a method for manufacturing a crystal resonator according to this embodiment will be described with reference to the drawings. First, a method for manufacturing the lower substrate wafer 40 will be described.
5A and 5B show the manufacturing process of the lower substrate wafer 40 according to the present embodiment, where FIG. 5A is a perspective view showing the lower surface 40a side, and FIG. 5B is a cross-sectional view showing the BB cut surface of FIG. It is. 5A and 5B, a recess 42 is formed as a space for forming a cavity by half-etching on the upper surface 40b side. The peripheral part of the recessed part 42 is the joint surface 43 (refer FIG. 2). And the recessed part 50 is formed in the lower surface 40a side.

  The recess 50 is formed by sandblasting the lower substrate wafer 40 at each intersection of the cutting lines 2. In the sandblasting process, the recess 50 is drilled to a predetermined depth using a mask having an opening of a predetermined size. In this embodiment, the remaining thickness is about 30 μm, the diameter of the opening on the lower surface 40a side is 200 μm, and the diameter of the bottom is 100 μm. The material, particle size, spraying speed, processing time, etc. of the abrasive in sandblasting are appropriately selected according to the desired depth of the recess 50 and the tapered shape.

Next, a method for manufacturing the upper substrate wafer 30 will be described with reference to FIG.
FIG. 6 is an explanatory view showing a state before the upper substrate wafer 30, the quartz substrate wafer 20 and the lower substrate wafer 40 are bonded. The upper substrate wafer 30 is shown in the uppermost layer of FIG. The upper substrate wafer 30 has a recess 32 formed as a space for forming a cavity on the back surface side (lower side in the drawing) by half etching. The concave portion 32 is formed at a position and size corresponding to the concave portion 42 of the lower substrate wafer 40 described above, and the peripheral portion of the concave portion 32 is a bonding surface 33 (see FIG. 2).

  The method for manufacturing the quartz substrate wafer 20 has been described with reference to FIGS. 3 and 4 and will be omitted. However, the tuning fork in which the base 24 and the vibrating arms 22 and 23 are extended from the frame 25 and the above-described tuning fork are described. In the state where each electrode is formed, a plurality of crystal vibrating pieces 21 are arranged to form a crystal substrate wafer 20. The upper substrate wafer 30, the crystal substrate wafer 20 and the lower substrate wafer 40 thus formed are accurately positioned, stacked, and bonded.

FIG. 7 is a cross-sectional view illustrating the bonding process to the connection electrode forming process. FIG. 7A shows the joining process. In the bonding process, the upper substrate wafer 30 is laminated on the upper surface of the quartz substrate wafer 20 and the lower substrate wafer 40 is laminated on the lower surface. In this state, the upper and lower substrate wafers and the quartz substrate wafer are heated and pressed and held by a hot plate (not shown). A positive electrode of a DC power supply 90 is connected to the substrate wafer 20, and a negative electrode is connected to the upper substrate wafer 30 and the lower substrate wafer 40, and voltage is applied to perform anodic bonding. The conditions of anodic bonding according to the present embodiment were that a predetermined bonding strength and hermeticity were obtained by applying a voltage of 0.5 to 1.4 kV for 5 minutes while applying pressure in an environment of 140 to 160 ° C. .
Note that there is no need to apply pressure due to the nature of the bonding. The bonding atmosphere can be performed in the air, in N ₂ or in a vacuum of 10 ⁻⁴ Pa or less.

  A plurality of recesses 50 are formed in the lower substrate wafer 40. Since these recesses do not penetrate, the occurrence of discharge during anodic bonding is suppressed.

Subsequently, a process of forming a connection electrode for taking out the first excitation electrode 26 and the second excitation electrode 27 after the anodic bonding process to an external electrode will be described.
The first excitation electrode 26 is connected to the lower conductive film 26a, and the second excitation electrode 27 is connected to the extraction electrode 27b through the upper conductive film 27a and the via hole 28 (FIGS. 3 and 4). However, since the structures of the connection electrodes 45 and 46 connected to the lower conductive film 26a and the extraction electrode 27b are the same, the lower conductive film 26a side will be described as an example.

  As shown in FIG. 7B, after the anodic bonding, a corrosion-resistant film 60 is formed on the lower surface 40 a side of the lower substrate wafer 40 in the state of the laminated body 1. The corrosion resistant film 60 has a three-layer structure including Cr, Au, and a resist film in this order from the substrate side. Cr and Au are formed to increase the adhesion between the glass and the resist. Further, a corrosion resistant film 61 is also formed on the upper surface of the upper substrate wafer 30. The structure of the corrosion resistant film 61 has a three-layer structure similar to that of the corrosion resistant film 60 described above, and is provided to protect the surface of the upper substrate wafer 30 during an etching process described later.

  Next, the corrosion resistant film on the inner surface of the recess 50 is removed by exposure and development. As shown in FIG. 7C, the corrosion-resistant film 60 is opened at the recess 50 portion.

Next, as shown in FIG. 7D, the bottom of the recess 50 is removed by an etching process to form a through hole 44. The etchant is processed using HF or H ₂ O ₂ + NH ₄ HF ₂ at a liquid temperature of about 25 to 30 ° C. until the surface of the lower conductive film 26a is exposed. Then, the corrosion resistant films 60 and 61 are peeled off and cleaned including the inner surface of the through hole 44 (not shown).

  Subsequently, as shown in FIG. 7E, a corrosion-resistant film 62 is formed on the lower surface 40a of the lower substrate wafer 40, and openings 62a are opened around the through-holes 44 and the through-holes 44 by exposure and development processes. To do. The opening 62a is a region where the external electrodes 45 and 46 are formed.

  Next, as shown in FIG. 7F, connection electrodes 47 and external electrodes 45 and 46) are formed by means such as sputtering. The external electrode 45 is connected to the lower conductive film 26a (that is, the first excitation electrode 26), and the external electrode 46 is connected to the extraction electrode 27b (that is, the second excitation electrode). Since the through hole 44 has a tapered shape when the recess 50 is formed, the connection electrode 47 is uniformly formed up to the inner side surface and the lower conductive film 26a (or the extraction electrode 27b) by sputtering from the lower surface side. Is possible.

  After the connection electrode 47 and the external electrodes 45 and 46 are formed, the corrosion-resistant film 62 is peeled off and washed to form the laminate 1 (not shown).

In addition, the process shown in FIG.7 (b)-FIG.7 (f) showed the suitable example of this embodiment, and it is possible to use another routing.
For example, it is possible to clean the through hole 44 (see FIG. 7D) and subsequently form the connection electrode 47 by a sputtering process. Then, corrosion-resistant film formation, exposure, development, and formation of external electrodes 45 and 46 may be performed. Further, it is possible to form a terminal by sputtering or vapor deposition using a metal mask, and in this case, a process such as formation of a corrosion-resistant film is not necessary.
In addition, the external electrodes 45 and 46 can be formed in advance before the through hole 44 is opened.

  Furthermore, the external electrodes 45 and 46 can be omitted. In such a case, a structure in which the connection electrode 47 corresponding to each of the first excitation electrode 26 and the second excitation electrode 27 is directly connected to a circuit board (not shown) using the notch 44a (see FIG. 1). It is good.

Subsequently, the laminated body 1 formed as described above is cut into pieces.
FIG. 8 is an explanatory view schematically showing a step of cutting the laminate 1. The laminate 1 is cut vertically and horizontally along the cutting line 2 and separated into individual pieces to form a crystal resonator 10 as shown in FIGS.

  Therefore, according to the first embodiment described above, the first excitation electrode 26 and the second excitation electrode 27 provided on the crystal vibrating piece 21 are provided in the through hole 44 provided in the lower substrate wafer 40 (in the individual piece, a notch 44a). In the structure of the crystal resonator 10 taken out from the outside, the through hole 44 is not penetrated until the anodic bonding is completed (the state of the recess 50), and the through hole 44 is opened after the anodic bonding. Since the occurrence of discharge in the through-hole 44 is excluded, it is possible to prevent the quartz crystal resonator element 21 and each of the electrodes described above from being damaged.

  Further, since the recess 50 is formed in the direction of the lower surface 40a of the lower substrate wafer 40, there is no opening in the bonding surface 43 between the lower substrate wafer 40 and the quartz substrate wafer 20, so that the state of the bonding surface 43 is smooth. Because of this uniform surface, there is an effect that it is easy to ensure the bonding quality.

  Moreover, since the opening in the direction of the lower surface 40a of the lower substrate wafer 40 is tapered so that the recess 50 is wider than the bottom, the connection electrode 47 is formed by sputtering from the lower surface 40a side of the lower substrate wafer 40. A continuous connection electrode can be suitably formed up to the depth of the lower conductive film 26a or the extraction electrode 27b on the upper surface 40b side.

  Further, by drilling this tapered recess 50 by sandblasting, it is easy to form a desired tapered shape by adjusting the material, particle size, spraying speed, time, etc. of the abrasive, and a plurality of Since the recess 50 can be formed at the same time in a short time, the production efficiency can be increased.

Furthermore, since the bottom of the recess 50 is removed by etching, the opening of the through hole as in the prior art described above does not cause damage to the lower substrate wafer 40 and variations in thickness compared to the polishing method. There is a great effect.
(Embodiment 2)

Next, a method for manufacturing a crystal resonator according to Embodiment 2 of the present invention will be described with reference to the drawings. The second embodiment is characterized in that a concave portion is formed on the upper surface 40b of the lower substrate wafer 40, and is the same as the first embodiment except for the steps from the concave portion formation to the through hole formation. Explanation is omitted, and common portions are denoted by the same reference numerals.
9A and 9B show a manufacturing process of the lower substrate wafer 40 according to the present embodiment, where FIG. 9A is a perspective view showing the upper surface 40b side, and FIG. 9B is a cross-sectional view showing a CC cut surface of FIG. It is. 9A and 9B, a concave portion 42 and a concave portion 51, which are spaces for forming a cavity by half etching, are formed on the upper surface 40b side.

The recess 51 is also formed by half etching around each intersection of the cutting lines 2 of the lower substrate wafer 40. As a means for forming the recess 51, the sand blast described in the first embodiment may be used, but in this embodiment, it is desirable to form the inner side surface perpendicular to the upper surface 40b by etching. The remaining thickness of the recess 51 is about 30 μm.
The lower substrate wafer 40 and the quartz substrate wafer 20 formed in this way are overlaid and stacked (see FIG. 6).
And the laminated body 1 is formed by anodic bonding.

  FIG. 10 is a partial cross-sectional view showing the connection electrode forming step after the anodic bonding step. The lower conductive film 26a side will be described as an example.

  FIG. 10A shows an anodic bonding process. In the bonding process, the upper substrate wafer 30 is laminated on the upper surface of the quartz substrate wafer 20, and the lower substrate wafer 40 is laminated on the lower surface. In this state, the upper and lower substrate wafers and the quartz substrate wafer are heated and pressed by a hot plate (not shown). A positive electrode of a DC power supply 90 is connected to the wafer 20, and a negative electrode is connected to the upper substrate wafer 30 and the lower substrate wafer 40, and voltage is applied to perform anodic bonding. The conditions for anodic bonding are the same as those in the first embodiment (see also FIG. 7).

  The lower substrate wafer 40 is formed with a plurality of recesses 51 having openings in the direction of the quartz substrate wafer 20, but these recesses are not penetrating, so that in anodic bonding, The occurrence of discharge that occurs is suppressed.

  Next, as shown in FIG. 10B, after anodic bonding, a corrosion-resistant film 60 is formed on the lower surface 40 a side of the lower substrate wafer 40 in the state of the stacked body 1. Similarly to the first embodiment, the corrosion-resistant film 60 has a three-layer structure composed of Cr, Au, and a resist film from the substrate side. Further, a corrosion resistant film 61 is also formed on the upper surface of the upper substrate wafer 30.

  Subsequently, as shown in FIG. 10C, unnecessary portions of the corrosion-resistant film are removed by exposure and development, and an opening 60 a having a shape corresponding to the recess 51 is formed.

Next, as shown in FIG. 10D, the bottom of the recess 51 is removed by an etching process to form a through hole 44. The etchant is processed using HF or H ₂ O ₂ + NH ₄ HF ₂ until the surface of the lower conductive film 26a is exposed. Then, the corrosion resistant films 60 and 61 are peeled off and cleaned including the inner surface of the through hole 44 (not shown).

  Subsequently, as shown in FIG. 10E, a corrosion-resistant film 62 is formed on the lower surface 40a of the lower substrate wafer 40, and openings 62a are opened around the through holes 44 and the peripheral portions of the through holes 44 by exposure and development processes. To do. The opening 62a is a region where a connection electrode and an external electrode are formed.

Next, as shown in FIG. 10F, a connection electrode 47 and external electrodes 45 and 46) are formed by means such as sputtering. The external electrode 45 is connected to the lower conductive film 26a (that is, the first excitation electrode 26), and the external electrode 46 is connected to the extraction electrode 27b (that is, the second excitation electrode 27). In the present embodiment, since the through hole 44 is formed substantially perpendicular to the upper surface 40b when the recess 51 is formed, the inner side surface and the lower conductive film 26a (or the extraction electrode) are formed by sputtering from the direction of the lower surface 40a. 27b), it is possible to form the connection electrode 47 that is continuously continuous.
After the connection electrode 47 and the external electrodes 45 and 46 are formed, the corrosion-resistant film 62 is peeled off and washed to form the laminate 1. And it cut | disconnects (refer FIG. 8) and singulated, and forms the crystal oscillator 10 as shown in FIG.

In this embodiment as well, the process may be performed in which the through-hole 44 is cleaned after opening (shown in FIG. 10D), and then the connection electrode 47 is formed by a sputtering process. Then, the order of forming the corrosion-resistant film, exposing, developing, and forming the external electrodes 45 and 46 may be adopted.
In addition, the external electrodes 45 and 46 can be formed in advance before the through hole 44 is opened.

  Furthermore, the external electrodes 45 and 46 can be omitted. In such a case, a structure in which the connection electrode 47 corresponding to each of the first excitation electrode 26 and the second excitation electrode 27 is directly connected to a circuit board (not shown) using the notch 44a (see FIG. 1). It is good.

  Therefore, according to the second embodiment described above, even when the recess 51 is formed in the direction of the upper surface 40b of the lower substrate wafer 40, the through hole 44 is not penetrated until the anodic bonding is completed (the recess 51 is formed). In addition, since the through hole 44 is opened after the anodic bonding, it is possible to prevent discharge from occurring during the anodic bonding.

  In this embodiment, the recess 51 is formed by an etching process. However, the upper surface 40b of the lower substrate wafer 40 is formed with a recess 42 that forms a cavity for housing a crystal vibrating piece by an etching process. Therefore, the recessed part 42 and the recessed part 51 can be formed in the same process, and productivity can be improved.

Moreover, although the recessed part 51 can be formed also by sandblasting etc., the recessed part formed by sandblasting becomes a taper shape. When this concave portion is viewed from the lower surface 40a side of the lower substrate wafer 40, it becomes a reverse taper. When the connection electrode 47 is formed by sputtering from the lower surface 40a side, the lower conductive film 26a in the direction from the lower surface 40a of the lower substrate wafer 40 to the upper surface 40b It is conceivable that the depth of the extraction electrode 27b is not reached. However, according to the etching, the side surface in the recess 51 can be formed substantially perpendicular to the lower surface 40 a of the lower substrate wafer, so that the connection electrode 47 can be formed in the entire inside of the through hole 44.
(Embodiment 3)

  Next, a method for manufacturing a crystal resonator according to Embodiment 3 of the present invention will be described. In the third embodiment, until the connection electrode 47 (including the external electrodes 45 and 46) is formed, it is formed by the method according to the first embodiment or the second embodiment described above, and then conductive inside the recess formed by the connection electrode 47. It is characterized by embedding substances. Only portions different from the first and second embodiments will be described.

  FIG. 11 is a cross-sectional view illustrating a part of the laminate 1 according to the third embodiment. Since the connection electrode 47 is formed along the inner surface of the through hole 44, a recess is formed in the center. The conductive member 70 is formed so as to fill the recess. The conductive member may be hole filling plating, solder, conductive adhesive, or the like.

  When hole-filling plating or solder is used as the conductive member, a base plating may be formed on the inner surface of the through hole 44 instead of the connection electrode 47.

  According to the third embodiment, the connection electrode 47 is formed in the above-described through hole 44 by sputtering or the like. However, when the through hole 44 is deep (the lower substrate wafer 40 is thick), the lower conductive film 26a or the lead-out electrode is formed. Although it may occur rarely that the electrode 27b is not uniformly formed to the depth of the electrode 27b, by filling the conductive member 70, the lower conductive film 26a or the extraction electrode 27b and the connection electrode 47 are more reliably connected. Can be done.

  In addition, in FIG. 11, although the recessed part shape formed with the manufacturing method by Embodiment 2 is illustrated, it is applicable also when forming the taper-shaped recessed part by Embodiment 1, and improves reliability more. Can do.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
That is, although the present invention has been illustrated and described with particular reference to particular embodiments, it is not intended to depart from the technical spirit and scope of the invention. Various modifications can be made by those skilled in the art in terms of materials, combinations, other detailed configurations, and processing methods between manufacturing processes.

  Therefore, the description limited to the shape, material, manufacturing process and the like disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. Descriptions of the names of members from which some or all of the limitations such as materials and combinations are removed are included in the present invention.

  For example, in the first to third embodiments described above, the crystal resonator has been described as an example. However, in the case of anodic bonding between glass and a different material, when it is necessary to form a through hole in the glass, the anodic bonding is performed. Then, the discharge in the through hole can be suppressed by opening the through hole by etching after anodic bonding instead of forming the through hole. Of course, it can be used for anodic bonding of two layers instead of three layers.

  Therefore, according to the above-described first to third embodiments, there is provided a method for manufacturing a crystal resonator that can prevent the crystal resonator element from being damaged by discharge during anodic bonding and can enhance the reliability of the bonding. be able to.

1 is a plan view showing a schematic structure of a crystal resonator according to a first embodiment of the invention. Sectional drawing which shows the AA cut surface of FIG. FIG. 3 is a plan view showing an electrode configuration on the upper surface side of the crystal resonator element according to the first embodiment of the invention. FIG. 3 is a plan view showing an electrode configuration on the lower surface side of the crystal resonator element according to the first embodiment of the invention. 5A and 5B show a manufacturing process of a lower substrate wafer according to the first embodiment of the present invention, where FIG. 5A is a perspective view showing a back surface side, and FIG. Explanatory drawing which shows the state before joining of the upper substrate wafer which concerns on Embodiment 1 of this invention, a crystal substrate wafer, and a lower substrate wafer. Sectional drawing which shows from the joining process which concerns on Embodiment 1 of this invention to a connection electrode formation process. Explanatory drawing which shows typically the process of cut | disconnecting the laminated body which concerns on Embodiment 1 of this invention. The manufacturing process of the lower substrate wafer concerning Embodiment 2 of this invention is shown, (a) is a perspective view which shows the surface side, (b) is sectional drawing which shows the CC cut surface of (a). The fragmentary sectional view which shows the anodic bonding process-connection electrode formation process which concerns on Embodiment 2 of this invention. Sectional drawing which shows a part of laminated body which concerns on Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laminated body, 2 ... Cutting line, 10 ... Quartz crystal oscillator, 20 ... Quartz substrate wafer, 21 ... Quartz vibrating piece, 22, 23 ... Vibrating arm, 25 ... Frame part, 26a ... Lower conductive film, 30 ... Top Substrate wafer, 31 ... upper substrate, 40 ... lower substrate wafer, 41 ... lower substrate, 44 ... through hole, 47 ... connection electrode, 50 ... recess.

Claims (8)

A plurality of piezoelectric vibrating pieces in which a vibrating arm and a frame portion around the vibrating arm are integrated are provided, and a first excitation electrode provided on the vibrating arm and the first excitation electrode are connected to a lower surface of the frame portion. A lower conductive film to be formed; a second excitation electrode; an upper conductive film formed on the upper surface of the frame portion and continuous with the second excitation electrode; and formed on a lower surface of the frame portion continuous with the upper conductive film. Forming a piezoelectric substrate wafer having a lead electrode,
Forming an upper substrate wafer made of glass in which a plurality of upper substrates having a bonding surface provided corresponding to the upper surface of the frame portion are disposed;
Forming a lower substrate wafer made of glass in which a plurality of lower substrates having a bonding surface provided corresponding to the lower surface of the frame portion are disposed;
Forming a laminate by anodically bonding the bonding surface of the upper substrate wafer, the frame portion of the piezoelectric substrate wafer, and the bonding surface of the lower substrate wafer;
Cutting the laminate along vertical and horizontal cutting lines to singulate the piezoelectric vibrator,
The step of forming the lower substrate wafer includes a step of forming a recess on the surface of the intersection of the cutting lines,
In the state in which the laminate is formed, the method further includes the step of opening a through hole in the recess, and the step of forming a connection electrode connected to the lower conductive film or the extraction electrode on the inner surface of the through hole. A method for manufacturing a piezoelectric vibrator characterized by the above. In the manufacturing method of the piezoelectric vibrator according to claim 1,
A method of manufacturing a piezoelectric vibrator, comprising forming the concave portion on a lower surface side of the lower substrate wafer. In the manufacturing method of the piezoelectric vibrator according to claim 1 or 2,
A method of manufacturing a piezoelectric vibrator, wherein the recess is formed in a tapered shape in which the opening on the lower surface side of the lower substrate wafer is wider than the bottom. In the manufacturing method of the piezoelectric vibrator according to claim 3,
A method for manufacturing a piezoelectric vibrator, wherein the recess is formed by a sandblasting process. In the manufacturing method of the piezoelectric vibrator according to claim 1,
A method of manufacturing a piezoelectric vibrator, comprising forming the concave portion on an upper surface side of the lower substrate wafer. In the manufacturing method of the piezoelectric vibrator according to claim 5,
A method of manufacturing a piezoelectric vibrator, wherein the recess is formed by an etching process. In the manufacturing method of the piezoelectric vibrator according to claim 1,
A method of manufacturing a piezoelectric vibrator, wherein the step of opening the through hole is an etching step. In the manufacturing method of the piezoelectric vibrator according to claim 1,
A method of manufacturing a piezoelectric vibrator, comprising a step of filling an inner surface of the connection electrode with a conductive member after the step of forming the connection electrode.

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