JP2006049979A - Method of manufacturing crystal diaphragm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems of a conventional method of manufacturing a crystal diaphragm that chipping is caused because air bubbles including an atmosphere in a space for an adhering process may enter a part between the surface of a crystal wafer and an adhesive tape and cutting water used for cutting enters air bubbles (1) and the chipping may has a possibility of incurring characteristic deterioration of individual crystal diaphragms and decrease the yield (2). <P>SOLUTION: The method of manufacturing the crystal diaphragms 13 disclosed herein includes a step of forming through-holes 12 by the photo lithography method and the etching each penetrated through a crystal wafer at each cross point of cutting lines for cutting the crystal wafer into the individual crystal diaphragms in the thickness direction of the crystal wafer by a succeeding step. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a crystal diaphragm, and more particularly to a method for manufacturing a crystal diaphragm having a good yield when forming a crystal diaphragm.

  In recent years, along with the remarkable miniaturization of devices such as mobile communication devices, further miniaturization of electronic components such as crystal resonators used in these devices is required. Further, with respect to the crystal resonator, there is a demand for an increase in the oscillation frequency in order to cope with an increase in the operating frequency of the CPU and the like simultaneously with downsizing.

  In order to meet such a demand, recently, a crystal vibration in a form (a so-called reverse mesa type) in which a reinforcing portion thicker than the vibration region is formed around a rectangular vibration region excited at several hundred MHz. Crystal resonators using plates have been developed. (For example, see Patent Document 1)

  In other words, the quartz diaphragm has a vibration region excited in the thickness-shear vibration mode and a reinforcing portion thicker than the thickness of the vibration region around the vibration region. For example, when quartz is used as the piezoelectric material and excitation is performed at 600 MHz in the thickness shear vibration mode, the thickness of the vibration region is about 2.7 μm. Note that the structure between the reinforcing portion and the vibration region forms a difference in thickness between the reinforcing portion and the vibration region on one main surface side with respect to both the front and back main surfaces of the crystal diaphragm. Therefore, the other main surface side of the crystal diaphragm is formed so that there is no step between the vibration region and the reinforcing portion and is on the same plane.

  Excitation electrode films that excite the fundamental wave in the thickness-shear vibration mode are formed at substantially the center of both main surfaces of the vibration region. In addition, an extraction electrode is formed which is electrically connected to the quartz crystal container formed at one end of the excitation electrode passing through the reinforcing portion and passing through the reinforcing portion and having a relatively large area of the quartz vibrating plate. Yes.

  As a method for manufacturing such a crystal diaphragm, a method is generally used in which a plurality of crystal diaphragms formed on one flat crystal wafer are cut and separated individually. First, a plurality of rectangular vibration regions obtained by processing the thickness from one main surface side of the crystal wafer to a thickness that excites a desired frequency in the thickness-shear vibration mode on a flat plate-shaped crystal wafer. As a method of processing the thickness of the vibration region at this time, a method of processing a crystal wafer by photolithography and etching is used.

  Next, an excitation electrode film and an extraction electrode film made of gold or an alloy are formed at predetermined positions on both main surfaces of the vibration region and on the front and back main surfaces of the quartz wafer that will be a reinforcing portion in a later step. Next, an adhesive tape is affixed to the entire surface of the other main surface of the flat crystal wafer. As the adhesive of this adhesive tape, an adhesive having a property that the adhesive force disappears when irradiated with ultraviolet rays (UV) is used.

  Next, the crystal wafer with the adhesive tape attached is crystallized by a cutting line along the outer shape of the crystal diaphragm in which a reinforcing portion having a predetermined thickness around the vibration region and a thickness of the crystal wafer is formed. Only the wafer is cut. A manufacturing method is used in which a quartz crystal plate cut from an adhesive tape is separated after cutting to obtain individual quartz plates.

In addition, about the manufacturing method of the above quartz diaphragms or quartz diaphragms, it is disclosed by the following literature.
JP 2001-308666 A Japanese Patent Laid-Open No. 2003-110388

  In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the above prior art document information.

  When the adhesive tape is applied to the other main surface of the crystal wafer having the above-described form, the atmosphere of the space where the application process is performed between the crystal wafer surface and the adhesive tape due to the influence of the warp of the crystal wafer, etc. In some cases, bubbles (unapplied part) including s may be contained. In addition to preventing the divided quartz diaphragm from falling apart when the quartz wafer is cut, this adhesive tape has an end portion of the cut surface of the quartz wafer to which the adhesive tape is attached during the cutting operation. There is also an important effect to prevent chipping (wafer chipping) from occurring on the (corner side face of the crystal diaphragm), but when bubbles are contained in the cut part, cutting is performed on the bubble part when cutting. Water enters and chipping occurs. The chipping may cause deterioration of characteristics as individual crystal diaphragms, and may reduce the manufacturing yield.

  In addition, there is a concern that chipping may cause a decrease in reliability due to mechanical strength deterioration of the quartz diaphragm itself, or a failure such as breakage in a blade used for cutting a quartz wafer.

The present invention solves the above-mentioned problems, and a thickness of a flat crystal wafer is processed by photolithography and etching from one main surface side of the crystal wafer to a thickness that excites a desired frequency in the thickness-shear vibration mode. A plurality of rectangular vibration areas are aligned in a matrix, and an adhesive tape is applied to the entire other main surface of the crystal wafer to reinforce the thickness of the predetermined area and the crystal wafer around the vibration area. In the manufacturing method of the crystal diaphragm, which is cut to form a part to obtain a plurality of crystal diaphragms,
Immediately before or immediately after the step of forming the vibration region in the crystal wafer, through holes that penetrate the crystal wafer in the thickness direction at intersections of cutting lines for cutting the crystal wafer into individual crystal vibration plates are formed by photolithography and etching. It is a manufacturing method of the crystal diaphragm characterized by comprising the process of forming.

  Further, in the method for manufacturing a crystal diaphragm described in the preceding paragraph, in the through hole forming step, the step of patterning the shape of the opening of the through hole on the main surface of the crystal wafer and the shape of the vibration region are set to those of the crystal wafer. It is also a method for manufacturing a quartz diaphragm, wherein the patterning process on the surface is performed simultaneously.

  By the above method for manufacturing a crystal resonator, the atmosphere in the bubbles generated when the adhesive tape is applied to the entire other main surface of the crystal wafer is exhausted from the through-hole formed near the bubbles, and the crystal wafer and the adhesive tape are removed. The entire surface can be applied uniformly.

  Therefore, it is possible to prevent chipping from occurring at the end of the cut surface of the crystal wafer to which the adhesive tape is attached during the cutting operation, greatly improve the manufacturing yield of the crystal diaphragm, and the strength of the crystal diaphragm itself. The effect that can be maintained. Further, since no chipping occurs, the blade used for wafer cutting hardly causes any troubles such as breakage.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a perspective view showing an embodiment in which an adhesive tape is attached to a quartz wafer on which a plurality of quartz diaphragms are formed in the present embodiment. 2 is an enlarged partial perspective view of a part of the quartz wafer disclosed in FIG. Further, FIG. 3 is a cross-sectional view of the quartz wafer as viewed from the side when cut along the cutting line A1-A2 shown in FIG. In each drawing, a part of the structure is not shown for the sake of clarity. Each dimension is also partially exaggerated, and in particular, the dimension in the thickness direction at each part is particularly exaggerated. Furthermore, in each figure, the same code | symbol shall show the same object.

  That is, a plurality of rectangular vibration regions 11 having a thickness processed from one main surface side of the quartz wafer to a thickness for exciting a desired frequency in the thickness-shear vibration mode on the rectangular flat plate-shaped quartz wafer 10 are arranged in a matrix. Form. In the thickness direction structure of the formed vibration region, a difference in thickness between one main surface of the crystal wafer 10 and the vibration region 11 is formed as a step on one main surface side of the crystal wafer 10. Therefore, the other main surface of the quartz wafer 10 is formed so as to be flush with the vibration region 11 without being stepped. As a method of processing the thickness of the vibration region 11 at this time, a method of processing the crystal wafer 10 by photolithography and etching is used.

  Next, at each intersection of a plurality of cutting lines for cutting the quartz wafer 10 into individual quartz diaphragms in a later process, each corner of the quartz diaphragm 13 in contact with these intersections is chamfered. A through-hole 12 that penetrates both the front and back main surfaces in the thickness direction of the crystal wafer 10 is formed in the shape. The size of the opening of the through-hole 12 is arbitrarily large enough to maintain the strength of the entire crystal wafer 10 and not to affect the vibration characteristics of the vibration region 11 when the crystal diaphragm 13 is individually formed. decide.

  Although the shape of the opening of the through hole 12 is rectangular in this embodiment, the strength of the entire quartz wafer 10 is maintained and the vibration characteristics of the vibrating region 11 are affected when the quartz diaphragm 13 is individually formed. As long as the shape is not given, a circular shape, an elliptical shape or a polygonal shape may be used. Further, as a method for forming the through hole 12, the same photolithography method as that for the vibration region 11 is used. Therefore, the patterning of the through hole 12 can be performed during the patterning process of the vibration region 11, and a part of the manufacturing process can be shortened by this method.

  Next, Ni—Cr is used as a base layer at a predetermined position on both main surfaces of the individual vibration regions 11 and on the front and back main surfaces of the crystal wafer 10 which will be the reinforcement portions of the individual crystal vibration plates 13 in a later step. A gold or alloy excitation electrode film 14 and extraction electrode film 15 are formed thereon by vapor deposition.

  Next, the adhesive tape 16 is affixed to the entire surface of the other main surface of the crystal wafer 10 that is flat. As the adhesive of the adhesive tape 16, an adhesive having a property that the adhesive strength is lost when irradiated with ultraviolet rays (UV) is used. At this time, if a bubble including the atmosphere of the space in which the pasting process is performed enters between the other main surface of the quartz wafer 10 and the adhesive tape 16, the through hole 12 closest to the bubble is used. The atmosphere in the bubbles is exhausted from between the other main surface of the crystal wafer 10 and the adhesive tape 16, and the adhesive tape 16 is uniformly attached to the entire surface of the other main surface of the crystal wafer 10.

  Next, the quartz wafer 10 to which the adhesive tape 16 is attached is aligned with the outer shape of the quartz vibrating plate 13 in which a reinforcing portion having a predetermined thickness and a thickness of the quartz wafer 10 is formed around the vibrating region 11. Only the quartz wafer 10 is cut by the cut line. At that time, since the adhesive tape 16 is uniformly attached to the entire other main surface of the crystal wafer 10, it is possible to uniformly reinforce all the cut surface end portions (side corner portions of the crystal diaphragm) of the crystal wafer. Chipping does not occur at the side corners of the crystal diaphragm 13 after cutting.

  Next, after the crystal wafer 10 is cut in a predetermined form, the adhesive tape 16 is irradiated with ultraviolet rays to eliminate the adhesive force of the adhesive tape 16, and the adhesive tape 16 is peeled from the crystal wafer 10. The quartz crystal plates 13 cut by this process are individually separated to obtain individual quartz crystal plates.

  In this embodiment, after the excitation electrode film 14 and the extraction electrode film 15 are formed on the main surface of the crystal wafer 10 and the vibration region 11 in which the through holes 12 are formed, the step of cutting and separating into individual crystal vibration plates is performed. However, after cutting and separating the quartz wafer and the vibration region in which the through holes are formed into individual quartz crystal plates, a plurality of the separated quartz crystal plates are arranged on a carrier or the like. Even if it changes to the process of forming an excitation electrode film | membrane and an extraction electrode in an excitation area | region and a reinforcement part, and also changes to the process of forming the vibration area | region 11 in the quartz wafer 10 which formed the through-hole 12 previously, The effect of the invention does not change, so it does not matter.

FIG. 1 is a perspective view showing a form in which an adhesive tape is attached to a quartz wafer on which a plurality of quartz diaphragms are formed. FIG. 2 is an enlarged partial perspective view of a part of the quartz wafer disclosed in FIG. FIG. 3 is a cross-sectional view of the quartz wafer as viewed from the side when cut along the cutting line A1-A2 shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Quartz wafer 11 ... Vibrating region 12 ... Through-hole 13 ... Quartz diaphragm 14 ... Excitation electrode film 15 ... Extraction electrode 16 ... Adhesive tape

Claims (2)

A rectangular vibration region obtained by processing a thickness from one main surface side of a quartz wafer to a thickness that excites a desired frequency in a thickness-shear vibration mode on a flat plate-shaped quartz wafer in a matrix by photolithography and etching. A plurality of alignments are formed, and an adhesive tape is applied to the entire other main surface of the quartz wafer, and the quartz wafer is cut so as to form a predetermined area and a reinforcing portion having a thickness of the quartz wafer around the vibration area. In the manufacturing method of the quartz crystal diaphragm to obtain a plurality of quartz diaphragms,
Immediately before or immediately after the step of aligning and forming the vibration region on the quartz wafer, a through-hole penetrating the quartz wafer in the thickness direction is formed at an intersection of cutting lines for cutting the quartz wafer into individual quartz plates. And a method of manufacturing a quartz diaphragm, comprising a step of forming by etching and etching.   2. The method of manufacturing a quartz diaphragm according to claim 1, wherein the through hole is formed by patterning the shape of the opening of the through hole on the main surface of the quartz wafer, and the shape of the vibrating region is the quartz wafer. And a step of patterning the main surface of the quartz crystal plate simultaneously.

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