JP2010057095A - Piezoelectric vibrator and method of manufacturing the same, and oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrator capable of performing batch processing in a wafer state while ensuring flexibility in designing a wiring pattern provided in a multilayer structure, and thus improving manufacturing efficiency. And a method of manufacturing the same and an oscillator.
A plurality of mounting regions 210 for mounting piezoelectric pieces 230 formed on a substrate 200 made of ceramic that includes glass and can be fired at a temperature lower than a predetermined reference temperature. A mounting step of mounting 230;
[Selection] Figure 1

Description

  The present invention relates to a piezoelectric vibrator, a manufacturing method thereof, and an oscillator.

  Conventionally, various types of crystal resonators using quartz have been developed as representative piezoelectric resonators. This crystal resonator is mounted on, for example, a mobile phone, and generates a clock signal that serves as a reference when each circuit operates.

  By the way, two types of quartz resonators have been developed depending on the shape of the container that houses and protects the quartz piece. 7A and 7B are exploded perspective views showing an example of the configuration of such a crystal resonator. That is, the crystal resonator 10 (FIG. 7A) on which the crystal piece 60 is mounted in the concave cavity 30 formed in the package 20 and the crystal piece 140 on the substrate 110 called a flat base are mounted. There is a crystal unit 100 (FIG. 7B).

  Specifically, as shown in FIG. 7A, the crystal resonator 10 uses a package 20 in which a concave cavity 30 is formed as a container for protecting the crystal piece 60. In the package 20, for example, a flat plate made of ceramic is prepared as the first layer, and a cavity 30 is formed by laminating a frame made of ceramic as the second layer on the flat plate.

  Thus, the mounting pad 40 is disposed on the inner bottom surface of the cavity 30 formed in the package 20, and the mounting pad 40 and the excitation electrodes 70 formed on both surfaces of the crystal piece 60 are electrically conductive adhesive. (Not shown).

  A metallized layer (metal layer) 50 is formed on the upper surface of the package 20, and a lower surface of the lid (lid) 80 is sealed so as to correspond to the metallized layer (metal layer) 50 formed on the upper surface of the package 20. A stop material 90 is applied. The crystal unit 10 is formed by bonding the metallized layer 50 and the sealing material 90.

  On the other hand, as shown in FIG. 7B, the crystal unit 100 includes a mounting pad 120 disposed on a substrate 110 called a flat base and excitation electrodes 150 formed on both surfaces of the crystal piece 140. The crystal piece 140 is mounted on the substrate 110 by connecting via a conductive adhesive (not shown).

  The cap 160 serving as a cover for protecting the crystal piece 140 is formed with a concave cavity 170, and the substrate 110 and the cap 160 are bonded via the bonding material 130 so as to accommodate the crystal piece 140. Has been. The substrate 110 and the cap 160 are both made of ceramic, for example.

The following is a list of literature names related to crystal units.
JP 2007-324852 A

  By the way, in recent years, as a method for manufacturing a crystal resonator, crystal pieces are collectively mounted in a plurality of cavities formed in advance on a substrate, and the substrate and the lid are joined using anodic bonding, and the so-called singulation is performed. A manufacturing method by batch processing in a wafer state has been proposed.

  However, in such a manufacturing method, when a ceramic substrate is used, the substrate shrinks when fired after forming a plurality of cavities in the substrate. In this case, since the degree of shrinkage varies depending on the position of the substrate, the dimensions of the cavity vary. Therefore, when performing batch processing in the wafer state, it is necessary to perform highly accurate positioning.

  In order to solve such a problem, as a material for the substrate and the lid, the degree of shrinkage during firing is small, and considering that the substrate and the lid are joined in a wafer state using anodic bonding, the material has ion conductivity. It has been proposed to use glass. When a wiring pattern is provided in a multilayer structure such as a ceramic substrate using this glass, there is a problem that the thickness becomes thicker than that of a ceramic substrate.

  However, when glass is used as the material for the substrate and the lid, it becomes difficult to ensure adhesion between different layers and conduction between different layers, compared to the case of using ceramic. There has been a problem that the wiring pattern cannot be freely designed. In addition, there is a problem that it is difficult to form a cavity by changing the shape for each different layer.

  The present invention provides a piezoelectric vibrator capable of performing batch processing in a wafer state while ensuring a degree of freedom in designing a wiring pattern provided in a multilayer structure, and thus improving manufacturing efficiency, and manufacturing the same. It is an object to provide a method and an oscillator.

  A method for manufacturing a piezoelectric vibrator according to an aspect of the present invention includes a plurality of piezoelectric pieces for mounting a piezoelectric piece formed on a ceramic substrate that includes glass and can be fired at a temperature lower than a predetermined reference temperature. A mounting step of mounting the piezoelectric piece on the mounting region, a bonding step of bonding the substrate and a lid formed to correspond to the substrate by anodic bonding via a metal film, and bonding And a piezoelectric vibrator forming step for forming a piezoelectric vibrator by separating the substrate and the lid into individual pieces.

  In the method for manufacturing a piezoelectric vibrator according to one aspect of the present invention, in the joining step, the lid made of the same ceramic or Kovar as the substrate is joined to the substrate.

  A piezoelectric vibrator according to an aspect of the present invention includes a substrate that includes glass, is made of ceramic fired at a temperature lower than a predetermined reference temperature, and has a mounting region for mounting a piezoelectric piece, and the substrate has A piezoelectric piece mounted on the mounting area; and a lid bonded to the substrate via a metal film by anodic bonding.

  In the piezoelectric vibrator according to one aspect of the present invention, the lid is made of the same ceramic or kovar as the substrate.

  In the piezoelectric vibrator according to one aspect of the present invention, the substrate is made of a low-temperature co-fired ceramic.

  An oscillator according to one aspect of the present invention includes a substrate that includes glass and is made of ceramic fired at a temperature lower than a predetermined reference temperature, and includes a mounting region for mounting a piezoelectric piece, and the mounting the substrate has A piezoelectric piece mounted in the region, a lid joined by anodic bonding via the metal film to the substrate, an oscillation circuit is formed inside, and electrically connected to the piezoelectric piece via the piezoelectric piece connecting electrode And a semiconductor chip electrically connected to an external connection terminal provided on the substrate via an external terminal connection electrode.

  In the oscillator according to one aspect of the present invention, the lid is made of the same ceramic or Kovar as the substrate.

  In the oscillator according to one aspect of the present invention, the substrate is made of a low-temperature co-fired ceramic.

  According to the piezoelectric vibrator, the manufacturing method thereof, and the oscillator of the present invention, it is possible to perform batch processing in a wafer state using anodic bonding while ensuring a degree of freedom in designing a wiring pattern provided in the multilayer structure. Therefore, manufacturing efficiency can be improved.

  In addition, according to the piezoelectric vibrator, the manufacturing method thereof, and the oscillator of the present invention, it is possible to prevent the occurrence of distortion and stress during heating.

  In addition, according to the piezoelectric vibrator, the manufacturing method thereof, and the oscillator of the present invention, it is possible to easily form a multilayer structure having an accommodating portion and to reduce the thickness.

  In addition, according to the piezoelectric vibrator, the manufacturing method thereof, and the oscillator of the present invention, it is not necessary to form an accommodating portion in the lid, and accordingly, it is not necessary to perform positioning when joining the substrate and the lid, thereby improving the production efficiency. Can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1A to 1C show a method for manufacturing a crystal resonator according to an embodiment of the present invention. First, as shown in FIG. 1A, a substrate called a flat base is prepared as the first layer. This substrate is made of, for example, a low-temperature co-fired ceramic (LTCC) that can be fired at a low temperature of about 900 ° C. or less lower than a predetermined reference temperature. The low temperature cofired ceramic includes a glass having ion conductivity.

  Next, a substrate having a plurality of cavities 210 is formed by laminating a frame 200A made of a low-temperature co-fired ceramic as a second layer on the substrate and forming a lattice-shaped cavity 210. 200 is formed. The cavity 210 corresponds to a housing portion as a mounting area on which the crystal piece 230 is mounted.

  As described above, if a low-temperature co-fired ceramic is used as the substrate 200, a multilayer structure having a cavity 210 can be easily formed and the thickness can be reduced as compared with the case where a conventional ceramic is used. Can do.

  Then, the substrate 200 on which the plurality of cavities 210 are formed is baked at a low temperature. In this case, since a low-temperature co-fired ceramic is used as the substrate 200, the substrate 200 is compared with a case where, for example, a predetermined reference temperature is set to about 1500 ° C. and fired at this temperature as in the conventional ceramic. The degree of shrinkage can be reduced. Accordingly, there is no variation in the dimensions of the cavity 210, and batch processing in the wafer state is possible.

  Thereafter, the mounting pads 220 are collectively formed on the inner bottom surface of each cavity 210. Then, as shown in FIG. 1B, by attaching a crystal piece 230 to the mounting pad 220 formed in each cavity 210 via a conductive adhesive (not shown), a plurality of wafers in a wafer state is obtained. The crystal pieces 230 are mounted together.

  As shown in FIG. 1C, a lattice-shaped frame 200A that forms the substrate 200 on the bonding surface to be bonded to the substrate 200 of the flat lid 240 made of low-temperature co-fired ceramic is formed by sputtering. For example, a metal film (not shown) made of, for example, aluminum (Al) or chromium (Cr) is formed. This metal film may be formed on the upper surface of the frame 200 </ b> A that forms the substrate 200.

  Thereafter, the substrate 200 and the lid 240 are bonded in a wafer state by anodic bonding in a vacuum or a nitrogen atmosphere. Since the low-temperature co-fired ceramic forming the substrate 200 and the lid 240 includes glass having ion conductivity, anodic bonding is possible. As described above, the substrate 200 and the lid 240 formed so as to correspond to the substrate 200 are bonded to each other through the metal film (not shown) by anodic bonding.

  In the present embodiment, since the plurality of cavities 210 are formed in the substrate 200, it is not necessary to form cavities in the lid 240, and accordingly, it is necessary to perform positioning when joining the substrate 200 and the lid 240. The production efficiency can be improved.

  In addition, since the board | substrate 200 and the lid | cover 240 are formed with the low-temperature co-fired ceramic which is the same material, a distortion and stress do not generate | occur | produce in the case of a heating. Moreover, compared with the case where it forms with glass, intensity | strength can be improved.

  Then, dicing is performed on the bonded substrate 200 and the lid 240 to divide them into individual pieces, thereby manufacturing a crystal resonator. As an example of the crystal resonator manufactured in this manner, a two-layer crystal resonator 250 is shown in FIG. 2A, and a three-layer crystal resonator 300 is shown in FIG. 2B.

  As shown in FIG. 2A, the two-layer crystal resonator 250 is provided with a flat plate 260A as the first layer, and as the second layer, a flat plate 260A is laminated on the flat plate 260A, thereby forming the flat plate 260A. And the substrate 260 and the cavity 270 formed of the frame 260B. A crystal piece 280 is mounted on the exposed area of the upper surface of the flat plate 260A, and a lid 290 is bonded to the upper surface of the frame 260B.

  On the other hand, as shown in FIG. 2B, in the three-layer crystal resonator 300, a flat plate 310A is prepared as a first layer, and a frame 310B is stacked on the flat plate 310A as a second layer. As a feature, a frame 310C having a shorter width than the frame 310B is stacked on the frame 310B. Thereby, the substrate 310 composed of the flat plate 310A and the frames 310B and 310C and the stepped cavity 320 are formed.

  A crystal piece 340 is mounted on the exposed area of the upper surface of the frame 310B, and a lid 350 is bonded to the upper surface of the frame 310C.

  Here, FIGS. 3A and 3B show a specific configuration of the crystal resonator 400 manufactured by the above-described manufacturing method. This crystal resonator 400 uses a substrate 410 on which a concave cavity 420 is formed as a container on which a crystal piece 450 is mounted. The substrate 410 is made of a low-temperature co-fired ceramic, and the low-temperature co-fired ceramic includes glass having ion conductivity. Thus, the substrate 410 includes glass, is made of ceramic fired at a temperature lower than a predetermined reference temperature, and has a cavity 420 as a mounting region for mounting the crystal piece 450.

  A mounting pad 430 is disposed on the inner bottom surface of the cavity 420 formed in the substrate 410, and the mounting pad 430 and the excitation electrodes 460 formed on both surfaces of the crystal piece 450 are interposed via a conductive adhesive 440. Connected. In this way, the crystal piece 450 is mounted in the cavity 420 included in the substrate 410.

  The lid 470 is made of a low-temperature co-fired ceramic like the substrate 410, and the substrate 410 and the lid 470 are joined by anodic bonding via a metal film 480 made of, for example, aluminum (Al) or chromium (Cr). .

  As described above, according to the present embodiment, it is possible to perform batch processing in a wafer state while ensuring a degree of freedom in designing a wiring pattern provided in the multilayer structure, thereby improving manufacturing efficiency. it can.

  Here, FIGS. 4 to 6 show configuration examples of the oscillator manufactured by using the above-described manufacturing method. Hereinafter, it demonstrates in order. First, as shown in FIGS. 4A to 4C, in the oscillator 500, a first cavity 520 having a concave shape is formed on the front surface side of the substrate 510, and a second concave shape is formed on the back surface side. The cavity 530 is formed. The substrate 510 is made of a low-temperature co-fired ceramic, and the low-temperature co-fired ceramic includes glass having ion conductivity.

  A crystal piece 550 is mounted on the inner bottom surface of the first cavity 520 via a conductive adhesive 540, and excitation electrodes 560 formed on both surfaces of the crystal piece 550 are connected to the conductive adhesive 540. ing. The lid 570 is made of a low-temperature co-fired ceramic like the substrate 510, and the substrate 510 and the lid 570 are joined by anodic bonding.

  On the other hand, on the inner bottom surface of the second cavity 530, a semiconductor chip 580 provided with connection electrodes 590 made of, for example, solder balls is mounted, and the semiconductor chip 580 has an oscillation circuit formed therein. . An external connection terminal 600 is provided on the back surface side of the substrate 510.

  The semiconductor chip 580 is electrically connected to the crystal piece 550 through the crystal piece connection electrode (that is, the piezoelectric piece connection electrode) among the connection electrodes 590 and externally connected through the external terminal connection electrode. The terminal 600 is electrically connected.

  Subsequently, as shown in FIG. 5, the oscillator 700 uses a substrate 710 having a concave shape and having a cavity 720 having a stepped portion 725 as a container on which the semiconductor chip 730 and the crystal piece 750 are mounted. . The substrate 710 is made of a low-temperature co-fired ceramic, and the low-temperature co-fired ceramic includes glass having ion conductivity.

  A semiconductor chip 730 provided with connection electrodes 740 is mounted on the inner bottom surface of the cavity 720, and the semiconductor chip 730 has an oscillation circuit formed therein. A crystal piece 750 is mounted on the surface of the stepped portion 725 via a conductive adhesive 760.

  The lid 770 is made of a low-temperature co-fired ceramic like the substrate 710, and the substrate 710 and the lid 770 are joined by anodic bonding. An external connection terminal 780 is provided on the back surface side of the substrate 710.

  The semiconductor chip 730 is electrically connected to the crystal piece 750 through the crystal piece connection electrode (that is, the piezoelectric piece connection electrode) among the connection electrodes 740 and externally connected through the external terminal connection electrode. The terminal 780 is electrically connected.

  Subsequently, as shown in FIGS. 6A and 6B, the oscillator 800 uses a substrate 810 on which a concave cavity 830 is formed as a container for mounting a crystal piece 860, and mounts a semiconductor chip 890 thereon. As a container to be used, a substrate 820 in which a concave cavity 840 is formed is used, and the substrates 810 and 820 are stacked. The substrates 810 and 820 are made of a low-temperature co-fired ceramic, and the low-temperature co-fired ceramic includes glass having ion conductivity.

  A crystal piece 860 is mounted on the inner bottom surface of the cavity 830 formed in the substrate 810 via a conductive adhesive 850, and the excitation electrodes 865 formed on both surfaces of the crystal piece 860 are electrically conductive adhesive 850. It is connected to the. The lid 870 is made of a low-temperature co-fired ceramic like the substrates 810 and 820, and the substrate 810 and the lid 870 are joined by anodic bonding. An external connection terminal 900 is provided on the back side of the substrate 810.

  On the other hand, a semiconductor chip 890 provided with a connection electrode 880 is mounted on the inner bottom surface of the cavity 840 formed in the substrate 820, and the semiconductor chip 890 has an oscillation circuit formed therein. An external connection terminal 910 is provided on the front surface side of the substrate 820, and an external connection terminal 920 is provided on the back surface side.

  The semiconductor chip 890 is electrically connected to the crystal piece 860 through the crystal piece connection electrode (that is, the piezoelectric piece connection electrode) of the connection electrodes 880 and the external connection terminals 900 and 910 in order, and is connected. The electrode 880 is electrically connected to the external connection terminal 920 through an external terminal connection electrode.

  The above-described embodiment is an example and does not limit the present invention. For example, as a material for the lid 240, Kovar (Kv) may be used instead of the low-temperature co-fired ceramic. In this case, the thickness can be further reduced. At that time, the expansion coefficient of the substrate 200 made of the low-temperature co-fired ceramic may be adapted to Kovar (Kv).

  In the above-described embodiment, the case where the substrate 200 on which the cavity 210 is formed and the flat lid 240 is anodically bonded has been described. However, the flat substrate and the lid on which the cavity is formed are connected to the anode. You may join.

  In the above-described embodiment, the crystal resonator on which the crystal piece 230 is mounted is manufactured. However, for example, a piezoelectric resonator on which various other piezoelectric pieces such as a piezoelectric ceramic are mounted may be manufactured. good.

  In the above-described embodiment, the substrate 200 made of a low-temperature co-fired ceramic is applied as the substrate. However, various other types of ceramics that contain glass and can be fired at a temperature lower than a predetermined reference temperature. This substrate may be applied.

It is a perspective view of the element according to process in the manufacturing method of the crystal oscillator by an embodiment of the invention. It is a longitudinal cross-sectional view which shows the cross-sectional structure of the crystal unit. It is the disassembled perspective view and longitudinal cross-sectional view which show the specific structure of the crystal oscillator. It is the disassembled perspective view and longitudinal cross-sectional view which show an example of the structure of the oscillator manufactured using the manufacturing method of the crystal oscillator. It is a longitudinal section showing an example of the composition of the oscillator manufactured using the manufacturing method of the crystal oscillator. It is the disassembled perspective view and longitudinal cross-sectional view which show an example of the structure of the oscillator manufactured using the manufacturing method of the crystal oscillator. It is a disassembled perspective view which shows an example of a structure of the conventional crystal oscillator.

Explanation of symbols

200, 410, 510, 710, 810, 820 Substrate 210, 420, 520, 530, 720, 830, 840 Cavity 220, 430 Mounting pad 230, 450, 550, 750, 860 Crystal piece 240, 470, 570, 770, 870 Lid 400 Crystal resonator 480 Metal film 500, 700, 800 Oscillator 580, 730, 890 Semiconductor chip 590, 740, 880 Connection electrode 600, 780, 900, 910, 920 External connection terminal

Claims (8)

A mounting step of mounting the piezoelectric piece on a plurality of mounting regions for mounting the piezoelectric piece formed on a ceramic substrate including glass and capable of firing at a temperature lower than a predetermined reference temperature; ,
A bonding step of bonding the substrate and a lid formed so as to correspond to the substrate by anodic bonding through a metal film;
A piezoelectric vibrator manufacturing method comprising: forming a piezoelectric vibrator by separating the bonded substrate and the lid into pieces. The joining step includes
The method for manufacturing a piezoelectric vibrator according to claim 1, wherein the lid made of the same ceramic or Kovar as the substrate is bonded to the substrate. A substrate including glass, made of ceramic fired at a temperature lower than a predetermined reference temperature, and having a mounting region for mounting a piezoelectric piece;
A piezoelectric piece mounted on the mounting region of the substrate;
A piezoelectric vibrator comprising: a lid joined by anodic bonding via the substrate and a metal film. The lid is
The piezoelectric vibrator according to claim 3, wherein the piezoelectric vibrator is made of the same ceramic or Kovar as the substrate. The substrate is
The piezoelectric vibrator according to claim 3 or 4, comprising a low-temperature co-fired ceramic. A substrate including glass, made of ceramic fired at a temperature lower than a predetermined reference temperature, and having a mounting region for mounting a piezoelectric piece;
A piezoelectric piece mounted on the mounting region of the substrate;
A lid joined by anodic bonding via the substrate and the metal film;
An oscillation circuit is formed inside, and is electrically connected to the piezoelectric piece via the piezoelectric piece connecting electrode and electrically connected to the external connection terminal provided on the substrate via the external terminal connecting electrode. An oscillator characterized by comprising: The lid is
The oscillator according to claim 6, wherein the oscillator is made of the same ceramic or kovar as the substrate. The substrate is
The oscillator according to claim 6 or 7, comprising a low-temperature co-fired ceramic.

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