JP2006180169A - Manufacturing method of vibrator package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of forming a vibrator package of a smaller size by bonding a wafer level. <P>SOLUTION: Glass wafers 102, 103 are anodic-bonded with a joining film 114 of a crystal wafer 101. Thus, a vibrator chip 112 is brought into a state of being sealed in a space configured by recessed parts 122, 123 in each chip region. Thereafter, outer side faces of the glass wafers 102, 103 are shaped by e.g., sand-blast processing to thin the glass wafers 102, 103 up to prescribed thicknesses. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a vibrator package covered with a cover made of glass or the like.

  Piezoelectric elements such as crystal filters and SAW filters are susceptible to damage due to changes in ambient temperature and humidity, or changes in characteristics caused by minute foreign matter, and mechanical vibrations and impacts. For this reason, the element mentioned above is sealed for use in a package. The package system is divided into a hermetic sealing system and a simple sealing system using a resin. In the SMD (Surface Mounted Device) type hermetic sealing system, materials such as ceramics and metals are mainly used. Further, as a cheaper hermetic sealing method, a hermetic sealing plastic package using plastic has been realized.

  In the above-described package, the package is formed individually for each element. On the other hand, after being sealed at the wafer level where a plurality of elements are simultaneously formed, the package is cut into individual elements (chips). There is also proposed a technique for forming a packaged chip (see Patent Document 1). In this technique, as schematically shown in the perspective view of FIG. 2, glass wafers 202 and 203 are bonded to a crystal wafer 201 on which a plurality of crystal resonator bodies are formed to seal the crystal resonator body portion. It is in the state. As shown in the plan view of FIG. 3, the plurality of chip portions formed on the crystal wafer 201 are composed of a frame portion 210 and a crystal resonator element 211 formed by hollowing out the periphery.

  In the state of the chip, as shown in the cross-sectional view of FIG. 4, the cover 215 and the cover 216 made of glass are bonded to the frame portion 210 via the bonding film 214, and the crystal resonator piece is sealed in the space sealed by these. 211 is arranged. Note that electrodes 212 are formed on both surfaces of the crystal resonator element 211, and a predetermined signal can be applied by wiring not shown. Further, as the bonding between the frame portion 210 and the cover 215 and the cover 216, anodic bonding using a bonding film 214 made of a metal such as aluminum has been proposed (see Patent Document 2). According to the package of the above-described form, mass production can be easily performed and the chip can be easily downsized.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
JP 2003-188436 A Japanese Patent No. 3390348

  By the way, while a smaller chip is required, it is better that the chip is formed thinner. Here, the crystal wafer in which the crystal resonator element and the frame are integrally formed is a part where the characteristics of the product are determined, and cannot be made thinner than a certain degree. Therefore, in order to obtain a thinner chip, the cover is made thinner. However, in order to obtain a mass production effect, it is better to use a wafer with a larger area. However, as the area of the wafer increases, it becomes difficult to use a thinner wafer. For example, when a glass wafer having a diameter of 3 inches is used, the thickness is limited to about 0.2 mm in order to prevent damage in a process such as bonding.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to enable a smaller vibrator package to be formed by bonding at a wafer level.

  A method of manufacturing a vibrator package according to the present invention includes a step of preparing a crystal wafer including a plurality of substantially rectangular chip portions in which a frame portion and a crystal resonator piece disposed inside the frame portion are integrally formed; The first glass wafer is bonded to the first main surface of the crystal wafer, and the second glass wafer is bonded to the second main surface on the back side of the first main surface of the crystal wafer. A step of cutting and thinning the outer surfaces of the first glass wafer and the second glass wafer in a state in which the first glass wafer and the second glass wafer are bonded to the crystal wafer, and a plurality of chip portions. And at least a step of making individual cutouts. Even when a thick glass wafer is used, a more compact state can be obtained in the chip state.

  As described above, according to the present invention, since the glass wafer is thinned after the glass wafer is bonded to the quartz wafer, even if a thick glass wafer is used, in the state of the chip, A miniaturized state can be obtained, and an excellent effect can be obtained that a smaller vibrator package can be formed by bonding at a wafer level.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram for explaining an example of a method for manufacturing a vibrator package according to an embodiment of the present invention. FIG. 1 is a cross-sectional view schematically showing a state in each step. First, as shown in FIG. 1A, a crystal wafer 101 having a predetermined thickness is prepared, and a frame portion 111 and a vibrator piece 112 are respectively formed in a plurality of chip regions 101a. The quartz wafer 101 is, for example, AT-cut for thickness shear vibration or + 2 ° X-cut for tuning fork bending vibration. By processing the crystal wafer 101 by a known photolithography technique and etching technique, the frame portion 111 and the vibrator piece 112 can be formed in each chip region 101a.

  Next, as shown in FIG. 1B, the electrode 113 is formed on the surface of each vibrator piece 112, and the bonding film 114 is formed on the frame 111. For example, a metal film made of an electrode material is formed on both surfaces of the quartz wafer 101 by sputtering or the like, and the formed metal film is processed by a known photolithography technique and etching technique, whereby the electrode 113 is formed. It can be in the formed state. Similarly, an aluminum film is formed on both surfaces of the quartz wafer 101 by sputtering or the like, and the formed aluminum film is processed by a known photolithography technique and etching technique, whereby the bonding film 114 is formed. State. Note that the frame portion 111 and the vibrator piece 112 may be formed after the electrode 113 and the bonding film 114 are formed.

  Next, as shown in FIG. 1 (c), a glass wafer (first glass wafer) 102 is prepared. Then, as shown in FIG. 1 (d), a bonding surface is formed on one surface of the glass wafer 102. It is assumed that a plurality of recesses 122 are formed in a region surrounded by the frame portion 121. The frame portion 121 is formed in a lattice shape, and a concave portion 122 is formed in a portion of the lattice, and the concave portion 122 is arranged corresponding to the above-described chip region 101a. Here, since the glass wafer 102 is bonded on the surface on the side where the recess 122 is formed, this surface is mirror-finished. As the glass wafer 102, a glass plate having a thickness of about 0.4 m whose both surfaces are polished may be used. If the glass plate has a certain thickness as described above, it can be obtained at a low cost, and the warpage due to the processing of the concave portion 122 can be reduced and the joining can be easily performed.

  Next, as shown in FIG. 1E, the surface of the bonding film 114 formed on one surface (first main surface) of the frame portion 111 of the crystal wafer 101 and the surface of the frame portion 121 of the glass wafer 102. Are in contact with each other. Further, the surface of the frame portion 121 of the glass wafer (second glass wafer) 103 formed in the same manner as the glass wafer 102 is also bonded to the other surface (second main surface) of the frame portion 111 of the crystal wafer 101. The state is in contact with the surface of the film 114. The stage before bonding the wafers is almost the same as the conventional state shown in FIG.

  After the wafers are brought into contact with each other as described above, the glass wafer 102, the glass wafer 103, and the quartz wafer 101 are first heated to about 150 ° C., for example. Next, with the bonding film 114 as an anode, cathodes are respectively disposed on the outer surfaces of the glass wafer 102 and the glass wafer 103 so that a predetermined electric field is applied, and the glass wafer 102 and the glass wafer are applied to the bonding film 114. 103 is anodically bonded. As a result, in each chip region, the vibrator element 112 is sealed in the space formed by the recess 122 and the recess 132.

  Next, the outer surfaces of the glass wafer 102 and the glass wafer 103 are shaved, and the glass wafer 102 and the glass wafer 103 are thinned to a predetermined thickness to obtain a predetermined thickness as shown in FIG. The glass wafer 102 a and the glass wafer 103 a are bonded to the bonding film 114 of the crystal wafer 101. For example, the outer surfaces of the glass wafer 102 and the glass wafer 103 may be cut by sandblasting. Until the thinning step, each glass wafer is in a thick state, and breakage in the formation of the concave portions 122 and the concave portions 132 and the bonding process is suppressed. In addition, when the layer is thinned, it is bonded to the crystal wafer 101, so that it is less likely to be damaged as compared with the case where the layer is thinned alone.

  Thereafter, for example, a terminal (external electrode) connected to the electrode 113 by a wiring (not shown) is formed on the outer surface of the glass wafer 102. The terminals are formed in each chip area. Since the outer surface is roughened by the sandblasting process described above, a state in which the terminals are more closely attached can be obtained. Next, the cutting area provided in the area of the frame portion 111 is cut and cut into individual chips, whereby the cover 120 and the cover 130 are anodically bonded to the bonding film 114 as shown in FIG. Thus, the vibrator package fixed to the frame portion 111 is obtained.

  According to the above-described method for manufacturing a vibrator package, a more compact vibrator package including a thinner cover can be easily obtained. According to the method described above, for example, it is easy to make the thickness of the cover 120 thinner than 0.4 mm. This is useful not only from the miniaturization of the package but also from the following. As described above, when glass is bonded to quartz, the materials have different coefficients of thermal expansion, so that stress remains inside after being heated and bonded. This residual stress warps in the case of a two-layer structure, and causes problems such as peeling of the joint portion in the case of a three-layer structure as shown in FIG. However, according to the manufacturing method described above, the thickness of the cover can be easily made thinner than 0.4 mm, so that the problem of residual stress after bonding is solved.

  Further, the above-described bonding may be performed in a state in which pressure is applied between the glass wafer 102 and the glass wafer 103 and pressed against the quartz wafer 101 side. For example, the wafers may be brought into contact with each other, heated, applied with a voltage, anodically bonded, and pressed and pressed until cooled to about room temperature. At this time, the pressing may be performed using a press plate made of a material whose thermal expansion is suppressed. As a result, expansion of each member due to heat is suppressed, and problems such as misalignment can be solved.

  In addition, according to the above-described embodiment, the glass wafer is in a state having a certain thickness at the time of bonding, so that even when pressed and pressed, it is difficult to break. Yes. In other words, according to the above-described embodiment, it is possible to use a glass wafer having a thickness that can withstand the pressing and pressing, so that it is possible to press and apply pressure during anodic bonding.

It is process drawing explaining the example of the manufacturing method of the vibrator package in embodiment of this invention. It is a perspective view which shows the structure of the conventional crystal oscillator package. It is a top view which shows a partial structure of the conventional crystal oscillator package. It is sectional drawing which shows the structure of the conventional crystal oscillator package.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Quartz wafer, 101a ... Chip area | region, 102 ... Glass wafer, 103 ... Glass wafer, 111 ... Frame part, 112 ... Vibrator piece, 113 ... Electrode, 114 ... Bonding film, 120 ... Cover, 121 ... Frame part, 122 ... recesses, 130 ... covers, 132 ... recesses.

Claims (1)

Preparing a crystal wafer comprising a plurality of substantially rectangular chip portions in which a frame portion and a crystal resonator piece disposed inside the frame portion are integrally formed;
The first glass wafer is bonded to the first main surface of the crystal wafer; and
The second glass wafer is bonded to the second main surface on the back side of the first main surface of the crystal wafer; and
In a state where the first glass wafer and the second glass wafer are bonded to the crystal wafer, the outer surfaces of the first glass wafer and the second glass wafer are scraped and thinned;
And a step of cutting the plurality of chip portions into individual cutouts.

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