JP2007013628A - Manufacturing method of piezoelectric vibrator and piezoelectric vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a piezoelectric vibrator and the piezoelectric vibrator, which reduce the cost, attain downsizing and a low height, and obtain a stable joining state. <P>SOLUTION: The piezoelectric vibrator manufactured by the method comprises: a substrate 10; a piezoelectric element 40 mounted on the substrate 10; and a lid 20 provided thereon with a recessed part 21 for sealing the piezoelectric element 40, wherein the substrate 10 and the lid 20 are joined to block the recessed part 21. The method includes: the substrate 10 the surface of which is processed flat; circuit 60 connected to the piezoelectric element 40, provided at the substrate 10, and acting like an oscillator; a mount pattern 31 for mounting the piezoelectric element formed on the substrate 10; a laying pattern 32 for being externally laid around the mount pattern 31; an external mount pattern 33 connected to the laying pattern 32; a metallic film 34 formed on a joining face of the substrate 10; and the piezoelectric element 40 mounted to each mount pattern by GGI bonding. The substrates 10 and the lids 20 anodic-joined in a wafer state are made in piece. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface-mountable piezoelectric vibrator manufacturing method and a piezoelectric vibrator.

Conventionally, as shown in FIG. 7, as a surface-mountable piezoelectric vibrator, a piezoelectric substrate 203 made of crystal in which a frame portion 203A and a vibrating portion 203B are integrally formed, a lid 201 and a substrate 202 made of glass together. There has been proposed a piezoelectric vibrator 200 that is sandwiched between layers (for example, see Patent Document 1).
In such a piezoelectric vibrator 200, in order not to deteriorate the vibration characteristics of the piezoelectric substrate 203, the lid 201 and the substrate 202 are formed with a recess 210 that can accommodate the vibrating portion 203 </ b> B. Further, a metal layer 203C is formed on both the back surface and the front surface of the frame portion 203A of the piezoelectric substrate 203, and the recess portion 210 is formed by anodic bonding of the frame portion 203A and the lid 201, and the frame portion 203A and the substrate 202. It joins toward the vibration part 203B.
In addition, a through hole 204 is provided in the surface of the substrate 202 that is bonded to the crystal in order to route the electrode to the outside. In this case, a mounting electrode 205 that covers one end of the through hole 204 is provided on the crystal side, and after joining the crystal and the substrate 202, a metal film 205 is provided inside the through hole 204 by sputtering to provide an external electrode. It is said.

In the method of manufacturing the piezoelectric vibrator 200, first, the lid 201 and the substrate 202 are diced from a wafer into individual pieces. Next, after the lid 201 and the substrate 202 are diced from the wafer into individual pieces, the frame portion 203A and the vibration portion 203B are integrally formed on the piezoelectric substrate 203, and a metal is formed on the back surface and the front surface of the outer frame 203A. A step of forming the layer 203C, a step of forming the recess 210 in the lid 201, a step of forming the recess 210 in the substrate 202, a step of forming the through hole 204 in the substrate 202, and one surface of the frame portion 203A A step of joining the lid 201 to the vibrating portion 203B by anodic bonding, a step of joining the other surface of the frame portion 203A and the substrate 202 to the vibrating portion 203B by anodic bonding, and Through this process, the piezoelectric vibrator 200 is manufactured.
In general, glass frit, resistance welding, seam welding, resin sealing, thermal fusion, EB sealing, and the like are known as hermetic sealing methods for vibrators and oscillators.

In addition, a sealing method in which a metal layer for bonding and a part of the extraction electrode are bonded by anodic bonding, heat-resistant adhesive, and eutectic bonding has been proposed (for example, see Patent Document 2).
Japanese Patent No. 3390348 (paragraphs 0005 to 0013, FIG. 3) Japanese Patent No. 362435

However, when assembling the piezoelectric vibrator with the substrate and lid in pieces, the manufacturing equipment becomes complicated to handle each component individually due to factors such as substrate accuracy, jig accuracy, and equipment accuracy. Management related to the manufacturing apparatus becomes complicated, or it becomes necessary to introduce new equipment, which causes an increase in cost.
Further, when assembling the piezoelectric vibrator with the substrate and the lid being in pieces, it is difficult to reduce the size and height of the piezoelectric vibrator because the equipment needs to grip or / and fix each component. ing.
In addition, the piezoelectric element made of quartz is not only costly to manufacture because the frame part and the vibrating part are integrally formed, but it also takes time to manufacture because it requires advanced etching technology. .
In addition, when a piezoelectric vibrator is used as an oscillator, an additional IC must be purchased and mounted on the piezoelectric vibrator, resulting in an increase in manufacturing cost.
Furthermore, when anodic bonding is performed with a quartz crystal sandwiched between glass, the expansion coefficient differs between the quartz crystal and the glass, so that stress remains after bonding, and it is difficult to obtain a stable bonded state.

  Further, if the sealing method according to Patent Document 2 is to be handled by a wafer in which the substrate is arranged in a matrix, it is necessary to insulate a part of the extraction electrode from the metal film for bonding in order to adjust individually. However, when this is done, there is a problem that anodic bonding cannot be performed.

  Accordingly, it is an object of the present invention to provide a piezoelectric vibrator manufacturing method and a piezoelectric vibrator that solve the above-described problems, reduce costs, enable a reduction in size and height, and obtain a stable bonded state. .

  In order to solve the above-described problems, the present invention provides a lid wafer made of glass in which a substrate wafer made of silicon, a piezoelectric element mounted on the substrate wafer, and concave portions for sealing the piezoelectric element are provided in a matrix. A metal film is formed on the bonding surface of the substrate wafer, a circuit that functions as an oscillator on the substrate wafer so as to be accommodated in the recesses, a mounting pattern for mounting the piezoelectric element, and this mounting pattern A method of manufacturing a piezoelectric vibrator in which a routing pattern that leads to the outside, an external mounting pattern connected to the routing pattern is formed, and the substrate wafer and the lid wafer are bonded so as to close the concave portion. A piezoelectric element mounting step for mounting the piezoelectric element on a pattern, and the substrate wafer and the lid wafer are positively sealed so as to close the recess. A method of manufacturing a piezoelectric vibrator, comprising: a wafer bonding step for bonding and hermetically sealing by bonding; and an individualization step for dividing the bonded substrate wafer and the lid wafer into individual pieces. is there.

  In the present invention, the piezoelectric element may be bonded to each mounting pattern by GGI bonding. In the present invention, the metal film may be Cr or Ag.

  The present invention also includes a substrate, a piezoelectric element mounted on the substrate, and a lid provided with a recess for sealing the piezoelectric element, and the substrate and the lid so as to close the recess. A piezoelectric vibrator connected to the piezoelectric element, a circuit that functions as an oscillator provided in the substrate so as to fit in the recess, and a substrate wafer so as to fit in the recess. A mounting pattern for mounting the piezoelectric element, a routing pattern for routing the mounting pattern to the outside, an external mounting pattern connected to the routing pattern, the substrate wafer is made of silicon or glass, and the lid wafer is a heat-resistant insulating material Formed on the bonding surface of the lid wafer, or the lid wafer is made of silicon or glass, and the substrate wafer is a heat-resistant insulating material. A metal film wherein formed on the bonding surface of the substrate wafer when Ranaru, a piezoelectric vibrator, characterized in that it comprises, and the piezoelectric element mounted to each mounting pattern.

  In the present invention, the piezoelectric element may be mounted on each mounting pattern by GGI bonding. In the present invention, the metal film may be Cr or Ag.

According to such a method for manufacturing a piezoelectric vibrator, the cost can be reduced, the size and the height can be reduced, and the bonding state between the substrate wafer and the lid wafer can be stabilized.
Further, according to such a piezoelectric vibrator, the cost can be reduced, the size and the height can be reduced, and the bonding state between the substrate and the lid can be stabilized.

(First embodiment)
Next, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate. The case where a blank type crystal is used as the piezoelectric element will be described in the piezoelectric vibrator of the present invention. A case where a metal film is formed on a substrate wafer (substrate) will be described. Unless otherwise specified, the through holes are provided at two corners located on the diagonal line of the portion to be the substrate.

FIG. 1 is an exploded perspective view showing an example of a state in which the piezoelectric vibrators according to the first embodiment of the present invention are arranged in a wafer shape. 2A is a cross-sectional view taken along line AA in FIG. 1, and FIG. 2B is a cross-sectional view illustrating an example of a state in which a piezoelectric element is mounted. FIG. 3 is a cross-sectional view showing a state before the lid wafer and the substrate wafer are bonded together. FIG. 4A is a cross-sectional view showing a state after the lid wafer and the substrate wafer are bonded, and FIG. 4B is a cross-sectional view showing a state of being separated into piezoelectric vibrators. FIG. 5A is a conceptual diagram illustrating an example of a formation state of a circuit functioning as an oscillator when through holes are provided at four corners, and FIG. 5B is a circuit illustrating an example of a circuit functioning as an oscillator. FIG. FIG. 6 is a flowchart showing an example of steps of a method for manufacturing a piezoelectric vibrator according to an embodiment of the present invention.
In FIG. 1 to FIG. 4, in order to clarify the explanation of the piezoelectric vibrator, a circuit that functions as an oscillator is omitted.

As shown in FIG. 4, the piezoelectric vibrator 100 according to the present invention includes a substrate 10, a lid 20 having a recess 21, a piezoelectric element 40, and a piezoelectric element 40 provided on the substrate 10 so as to be accommodated in the recess 21. Functions as an oscillator provided on the substrate 10, a wiring pattern 32 for routing the mounting pattern 31 to the outside, an external mounting pattern 33 connected to the routing pattern 32, a metal film 34 for anodic bonding, and the substrate 10. The circuit 60 is constituted.
In addition, description of the manufacturing method of the piezoelectric vibrator according to the first embodiment of the present invention is included in the description of each component, and redundant description is omitted.

The plurality of substrates 10 are made of silicon, arranged in a matrix before being singulated, and are in a wafer (hereinafter referred to as “substrate wafer”) state as a whole (see FIG. 1).
Each substrate 10 is provided with a circuit recess 19 for providing a circuit 60 that functions as an oscillator, which will be described later, and the circuit 60 that functions as an oscillator and the piezoelectric element 40 can be hermetically sealed. ing.
Further, the plurality of lids 20 are made of glass, and the recesses 21 are arranged in a matrix before being singulated, so that the entire lid 20 is in a wafer state (hereinafter referred to as “lid wafer”) ( (See FIG. 1).
.. Of the substrate wafer KW corresponds to the arrangement position of the lids 20, 20... Of the lid wafer FW (see FIG. 1).

Further, the surface of the substrate wafer KW may be processed flat. This treats the surface of the substrate wafer KW flatly for anodic bonding with the lid wafer FW.
When processing or processing the substrate wafer KW, the substrate wafer KW can be easily fixed by using, for example, a processing machine (not shown) provided with a suction type fixed bed.
Further, it is desirable that the surface of the substrate wafer KW and the lid wafer FW described later is flattened by mirror polishing.

Then, as shown in FIGS. 5A and 5B, a circuit 60 (hereinafter sometimes simply referred to as “circuit”) functioning as an oscillator on the substrate 10 (the portion of the substrate wafer KW that becomes the substrate 10). Provide.
As shown in FIG. 5B, the circuit 60 includes, for example, an inverter 61, a feedback resistor Rf, a drain resistor Rd, a gate capacitor Cg, and a drain capacitor Cd.
As a connection state, the inverter 61 and the feedback resistor Rf are connected in parallel, the drain resistor Rd and the output side of the inverter 61, the drain resistor Rd and the feedback resistor Rf are connected in series, and the inverter 61 and the feedback resistor are connected. Rf is connected to the piezoelectric element 40. This portion is referred to as a connection portion XT1. A portion where the drain resistor Rd and the piezoelectric element 40 are connected is referred to as a connection portion XT2. The connection part XT1 is connected to the gate capacitor Cg grounded to the ground and to one terminal of the mounting pattern 31. The connection portion XT2 is connected to the drain capacitor Cd grounded to the ground and is connected to the other terminal of the mounting pattern 31.

The inverter 61, the feedback resistor Rf, the drain resistor Rd, the gate capacitor Cg, and the drain capacitor Cd may be provided on the substrate 10 that is not in contact with the mounted piezoelectric element 40, or the piezoelectric element 40 is mounted. You may provide in the back surface with respect to the surface to be.
The circuit 60 can also be provided with wiring for supplying power.

  For example, as shown in FIG. 5A, when the through holes 11 are provided at the four corners of the substrate 10, the through hole 11 close to one terminal of the mounting pattern 31 is connected to GND and the other terminal of the mounting pattern 31. When the through hole 11 close to Fout and the GND through hole 11 opposite to GND is Vcc and the through hole 11 opposite to Fout is set to Vcc, the terminal XT1 of the circuit 60 is connected to the terminal of the mounting pattern 31 closer to the through hole 11 to be GND. XT2 of the circuit 60 may be connected to the terminal of the mounting pattern 31 closer to the through hole 11 serving as Fout.

  In this way, by configuring the circuit 60, the crystal resonator 100 can function as an oscillator. Accordingly, there is no need to separately purchase an IC and mount it on the piezoelectric vibrator as in the prior art, so that the cost of purchasing the IC and the cost of mounting it become unnecessary, thereby reducing the manufacturing cost of the piezoelectric vibrator 100. Can do.

  Here, the through hole 11 is provided before the circuit 60 is formed on the substrate.

Also, as shown in FIGS. 1 and 2A, the substrate wafer KW leaves a bonding surface for anodic bonding with the lid wafer FW, that is, the substrate wafer is accommodated in the provided recess 21. A mounting pattern 31 is formed on a portion of the KW substrate 10, and a routing pattern 32 and an external mounting pattern 33 for routing the mounting pattern 31 to the outside are formed on the portion of the substrate 10. In addition, the mounting pattern 31, the routing pattern 32, and the external mounting pattern 33 are provided with a conductive material.
The mounting pattern 31, the routing pattern 32, and the external mounting pattern 33 are made of Au, and the mounting pattern 31 that mounts the piezoelectric element 40 is connected to the routing pattern 32 that leads the mounting pattern 31 to the outside. The external mounting pattern 33 is connected.
Further, the routing pattern 32 is provided through the through hole 11 provided in the bonding surface on the substrate 10 of the substrate wafer KW in order to connect the mounting pattern 31 and the external mounting pattern 33.

  The metal film 34 can be made of a material (oxide) that is formed on the bonding surface of the substrate wafer KW and can be covalently bonded. In particular, a material having a strong ionization tendency, for example, Al, Cr, Ag or the like is desirable.

As shown in FIG. 2B, the piezoelectric element 40 on which the electrode 41 is formed is mounted on the mounting pattern 31 by GGI bonding (see FIG. 6, S1) (piezoelectric element mounting step).
The electrode 41 formed on the piezoelectric element 40 is Au, and is formed in a film shape on the surface of the piezoelectric element 40, and a bump B is formed on a portion mounted on the mounting pattern 31. .

  On the substrate wafer KW on which the piezoelectric elements 40 are mounted in this way, a mounting pattern 31, a routing pattern 32, and an external mounting pattern 33 are formed corresponding to the substrates 10 arranged in a matrix, respectively. A piezoelectric element 40 is mounted. Therefore, the piezoelectric elements 40 are arranged in a matrix on the substrate wafer KW.

  In this state, the frequency of each piezoelectric element 40, 40... On the substrate wafer KW is adjusted (see FIG. 6, S2).

In addition, in the lid wafer FW, concave portions 21 are formed in a matrix in each portion that becomes the lid 20.
The concave portion 21 is formed in a portion that becomes the lid 20 of the lid wafer FW to the extent that it does not come into contact with a piezoelectric element 40 (described later) mounted on the base wafer KW.
When processing or transporting the lid wafer FW, the lid wafer FW can be easily fixed by using, for example, a processing machine (not shown) provided with a suction type fixing arm.

  And the surface which provided the recessed part 21 of the lid | cover wafer FW, ie, the surface joined to the substrate wafer KW, may be processed flat. In this case, the surface of the lid wafer FW is processed flatly for anodic bonding with the substrate wafer KW.

In this state, the substrate wafer KW and the lid wafer FW are overlapped and anodic bonded so that the piezoelectric element 40 fits in the recess 21 formed in the lid wafer FW (see FIG. 6, S3) (wafer bonding process) ) Seal hermetically.
At this time, the metal film provided on the bonding surface of the substrate wafer KW is bonded to the lid wafer FW, and the routing pattern 32 is not bonded to the lid wafer FW, and the substrate wafer KW and the lid wafer FW are bonded. is doing.
As a result, the substrate wafer KW and the lid wafer FW are joined, and a plurality of piezoelectric vibrators 100, 100... Are arranged in a matrix.
For anodic bonding, various conditions conventionally used can be applied as they are.
As an example, this is performed by applying a voltage of 500 V to 1000 V at a temperature of 200 ° C. to 400 ° C.

  In this way, the plurality of piezoelectric vibrators 100, 100..., That is, the respective substrates 10 and the lid 20 bonded in a wafer state are separated into pieces by using dicing, laser, or the like. (Refer to FIG. 6, S4) (individualization step). If comprised in this way, several piezoelectric vibrator 100,100 ... will be obtained at once.

  Thus, by using the substrate wafer KW in which the substrates 10 are arranged in a matrix and the lid wafer FW in which the lids 20 are arranged in a matrix, the substrate wafer KW and the lid wafer FW can be fixed or / and Since the gripping can be easily performed, the mounting pattern 31, the routing pattern 32, the external mounting pattern 33, and the piezoelectric element 40 can be easily formed on the substrate wafer KW, and the piezoelectric element 40 can be recessed in the lid wafer FW. Since the substrate wafer KW and the lid wafer FW are anodic bonded to each other so as to fit within the substrate wafer KW, the piezoelectric vibrator can be reduced in size and height.

In addition, compared with the conventional case where the substrate and the lid are assembled in the state of individual pieces, a jig for assembling and transporting is not required, so that the cost can be reduced.
Moreover, since the substrate and the piezoelectric element are GGI bonded, bonding is easy, and by forming a metal film on the bonding surface of the substrate wafer or the lid wafer, the metal film can be easily formed. The anodic bonding can be easily performed, and the cost can be reduced.

In addition, since it is possible to join a heat-resistant insulating material that cannot be joined to a material such as silicon or glass, the degree of freedom in design can be increased, and a material that is less expensive than a material such as silicon or glass can be used. Therefore, the cost can be reduced.
Further, since the drawing pattern 32 is apparently in contact with the lid 20 but is not in a joined state, the deformation of the lid 20 and the influence of heat conduction can be reduced as compared with the case of joining.

(Second embodiment)
Next, a piezoelectric vibrator according to a second embodiment of the present invention will be described.
The piezoelectric vibrator (not shown) according to the second embodiment of the present invention is different from the first embodiment in that a metal film (not shown) is formed on the lid wafer.
Thus, even if the piezoelectric vibrator according to the second embodiment is configured, the same effects as those of the first embodiment can be obtained.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. For example, ceramic or the like can be used as the piezoelectric element in addition to quartz.
In addition, the frequency adjustment of the piezoelectric element may be performed after separation, or after the wafer bonding step and before the separation step, it may be inspected whether the bonding state is good.
In addition, when a metal film is formed over the heat-resistant insulating material, a binder material may be provided between the heat-resistant insulating material and the metal film. By doing so, the bond between the heat-resistant insulating material and the metal film can be strengthened.

It is an exploded perspective view showing an example of the state where the piezoelectric vibrator concerning a first embodiment of the present invention was arranged in the shape of a wafer. (A) is AA sectional drawing in FIG. 1, (b) is sectional drawing which shows an example in the state which mounted the piezoelectric element. It is sectional drawing which shows the state before joining a cover wafer and a substrate wafer. (A) is sectional drawing which shows the state after joining a cover wafer and a substrate wafer, (b) is sectional drawing which shows the state separated into the piezoelectric vibrator. (A) is a conceptual diagram which shows an example of the formation state of the circuit which functions as an oscillator at the time of providing a through hole in four corners, (b) is a circuit diagram which shows an example of the circuit which functions as an oscillator. 4 is a flowchart showing an example of steps of a method for manufacturing a piezoelectric vibrator according to an embodiment of the present invention. It is sectional drawing which shows the conventional piezoelectric vibrator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Piezoelectric vibrator 10 Substrate 20 Lid 21 Recessed part 31 Mounting pattern 32 Leading pattern 33 External mounting pattern 34 Metal film 40 Piezoelectric element 41 Electrode 60 Circuit (circuit functioning as an oscillator)
KW Substrate wafer FW Lid wafer B Bump

Claims (6)

A substrate wafer made of silicon, a piezoelectric element mounted on the substrate wafer, and a lid wafer made of glass provided with a concave portion for sealing the piezoelectric element in a matrix, and the bonding surface of the substrate wafer In addition, a circuit that functions as an oscillator on the substrate wafer, a mounting pattern for mounting the piezoelectric element, a routing pattern for routing the mounting pattern to the outside, and the routing pattern A method of manufacturing a piezoelectric vibrator in which a connected external mounting pattern is formed and the substrate wafer and the lid wafer are bonded so as to close the concave portion,
A piezoelectric element mounting step of mounting the piezoelectric element on each mounting pattern;
A wafer bonding step of airtightly sealing the substrate wafer and the lid wafer by anodic bonding so as to close the concave portion;
A process for dividing the bonded substrate wafer and the lid wafer into individual pieces,
A method of manufacturing a piezoelectric vibrator.   The method for manufacturing a piezoelectric vibrator according to claim 1, wherein the piezoelectric element is bonded to each mounting pattern by GGI bonding.   The method for manufacturing a piezoelectric vibrator according to claim 1, wherein the metal film is made of Cr or Ag. A piezoelectric device comprising a substrate, a piezoelectric element mounted on the substrate, and a lid provided with a recess for sealing the piezoelectric element, and the substrate and the lid are joined so as to close the recess. A vibrator,
A circuit that is connected to the piezoelectric element and functions as an oscillator provided on the substrate so as to be accommodated in the recess;
A mounting pattern for mounting the piezoelectric element on the substrate wafer so as to fit in the recesses, a routing pattern for routing the mounting pattern to the outside, an external mounting pattern connected to the routing pattern,
When the substrate wafer is made of silicon or glass and the lid wafer is made of a heat-resistant insulating material, it is formed on the bonding surface of the lid wafer, or the lid wafer is made of silicon or glass, and the substrate wafer is heat-resistant A metal film formed on the bonding surface of the substrate wafer when made of a conductive insulating material;
The piezoelectric elements mounted on the mounting patterns;
A piezoelectric vibrator comprising:   The piezoelectric vibrator according to claim 4, wherein the piezoelectric element is mounted on each mounting pattern by GGI bonding.   The piezoelectric vibrator according to claim 4 or 5, wherein the metal film is made of Cr or Ag.

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