JP2015050616A - Quartz wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce occurrence of cracking even if cooling from the highest temperature.SOLUTION: From a crystal substance of artificial quartz, a flat sheet of Z-cut is cut out at a cut angle in a direction orthogonal to the Z axis, out of the crystal axes of the quartz, i.e., X axis, Y axis and Z axis, and parallel with the X axis and Y axis. For example, irregularities on a surface cut out by wrapping process are reduced, arithmetic average roughness Ra of the surface becomes Ra≤0.2 μm by the polishing process, and the outer peripheral edge of a parallel plate is chamfered.

Description

  The present invention relates to a quartz wafer formed on a flat plate.

Conventionally, a thin plate-like wafer is used when manufacturing an integrated circuit element (hereinafter also referred to as “IC”) or a piezoelectric thin film component. As this plate-like wafer, for example, thinly processed quartz glass (for example, see Patent Document 1) or ceramic (for example, see Patent Document 2) is used.
In some cases, a thin film for forming an electronic circuit pattern or a piezoelectric component is provided on the surface of the plate-like wafer.
When this thin film is provided, the film is formed at a high temperature of 800 ° to 1000 °.

International Publication No. 00/063956 JP 2004-282514 A

However, in a conventional plate-like wafer, when it is cooled from the maximum temperature, it contracts and the plate-like wafer may break.
Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a crystal wafer that can reduce the occurrence of cracks even when cooled from the maximum temperature.

In order to solve the above-mentioned problems, the present invention is a quartz wafer, which is cut out from a crystal of artificial quartz with a Z-cut flat plate, and has an arithmetic average roughness Ra of Ra ≦ 0.2 μm. To do.
Further, the present invention is characterized in that the outer peripheral edge of the flat plate is chamfered.

  According to such a quartz wafer, it is cut out from an artificial quartz crystal by a Z-cut parallel plate, and the arithmetic average roughness Ra of the surface is Ra = 0.2 μm or less, so that the surface unevenness is the starting point. A Z-cut parallel plate that is a cut angle in a direction perpendicular to the Z-axis and parallel to the X-axis Y-axis among the X-axis, Y-axis, and Z-axis that is the crystal axis of the crystal while reducing the occurrence of cracks Therefore, since the voids are uniformly formed in the atomic bond state of the crystal, the occurrence of cracks can be reduced even when cooled from the maximum temperature.

It is a perspective view which shows an example of the crystal wafer which concerns on embodiment of this invention. It is a schematic diagram which shows an example of the crystal structure of the crystal wafer of the main surface side which concerns on embodiment of this invention. It is a schematic diagram which shows an example of the crystal structure of the crystal wafer of the side surface which concerns on embodiment of this invention. It is a schematic diagram which shows the state which cut | disconnected the crystal structure of the crystal wafer of the main surface side which concerns on embodiment of this invention. It is a schematic diagram which shows the state which cut | disconnected the crystal structure of the crystal wafer of the side surface which concerns on embodiment of this invention.

  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. Note that each component is exaggerated for easy understanding of the state. Moreover, let the main surface be the widest surface and a surface parallel to the surface, and let the surface surrounding this main surface be a side surface.

  As shown in FIG. 1, a crystal wafer 10 according to an embodiment of the present invention is formed in a disk shape, for example, and is provided with an orientation flat (hereinafter referred to as “orientation flat”) at a predetermined position. .

The quartz wafer 10 is a flat plate having a predetermined thickness and formed in a circular shape in plan view.
A predetermined portion of the flat crystal wafer 10 is provided with an orientation flat so that the direction of the crystal axis of the crystal can be known.
For example, the main surface of the crystal wafer 10 is orthogonal to the Z axis, which is one of crystal axes of the crystal, and is parallel to the X axis and the Y axis. At this time, the orientation flat is provided so as to be parallel to the Y axis.

  As shown in FIGS. 2 to 5, such a crystal wafer 10 has holes (gap) 12 of atomic size in a lattice shape in the crystal structure of the crystal. The generation of cracks due to expansion can be prevented by reducing the size of the holes 12, and the occurrence of cracks can be reduced by returning the holes 12 to their original size even if the expansion is reduced by cooling from the expansion due to heating. Can do.

  For example, as shown in FIGS. 2 and 4, the crystal wafer 10 according to the embodiment of the present invention is in a state in which holes 12 penetrating in the Z-axis direction are vacant in a lattice shape. Moreover, as shown in FIGS. 3 and 5, the crystal wafer 10 according to the embodiment of the present invention is in a state where a space is also formed in the X-axis direction. As a result, even if the crystal wafer 10 expands due to heating, the space of these holes 12 is narrowed to maintain the crystal structure, and even if the crystal wafer 10 contracts due to cooling, the space of these holes 12 returns to its original state. Will be maintained. Thereby, the crystal wafer 10 according to the embodiment of the present invention can reduce the occurrence of cracks even if it is cooled after heating.

The surface 11 of the main surface of the quartz wafer 10 has an arithmetic average roughness Ra of Ra ≦ 0.2 μm.
Here, when the arithmetic average roughness Ra is set to Ra ≦ 0.2 μm, it is possible to reduce the occurrence of cracks due to unevenness on the surface 11.
When the arithmetic average roughness Ra is Ra> 0.2 μm, cracks may occur from the boundary between the surface irregularities.

The crystal wafer 10 according to the embodiment of the present invention can be manufactured by the following method.
For example, although not shown, a crystal body of artificial quartz is cut at a predetermined thickness to form a plate-shaped quartz wafer. The quartz wafer at this stage is in a state where the surface of the main surface is roughened by the processing after cutting.
A lapping process is performed in which the quartz wafer main surface is polished using a polishing agent having a roughness of # 800 to # 1700 using a double-side polishing machine to reduce large irregularities on the quartz wafer main surface. Do. At this time, the arithmetic average roughness Ra of the quartz wafer is, for example, 0.4 μm ≦ Ra ≦ 0.8 μm.
The quartz wafer subjected to the lapping process is subjected to a polishing process using a # 3000 grindstone, for example, until the arithmetic average roughness Ra becomes Ra ≦ 0.2 μm.

  In addition, the quartz wafer 10 according to the embodiment of the present invention is preferably heated to, for example, 1150 ° and maintained at this temperature for a predetermined time, and then gradually lowered to cool to, for example, the room temperature. Here, when the temperature is lowered, it is preferable that the rate of the temperature drop is made constant or cooled so as to draw a functionally gentle curve.

  By doing so, the quartz wafer 10 according to the embodiment of the present invention is cut out from the crystal body of the artificial quartz crystal by a Z-cut parallel plate, and the arithmetic average roughness Ra of the surface is Ra = 0.2 μm or less. This reduces the occurrence of cracks starting from unevenness on the surface, and cuts in the direction perpendicular to the Z axis and parallel to the X axis among the X, Y, and Z axes that are the crystal axes of the crystal Since it is a Z-cut parallel plate that is an angle, the gaps are evenly formed in the atomic bond state of the crystal, so that the generation of cracks can be reduced even when cooled from the maximum temperature. it can.

10 Crystal wafer 11 Surface 12 Hole

Claims (2)

  A quartz wafer characterized by being cut out from an artificial quartz crystal by a Z-cut flat plate and having an arithmetic average roughness Ra of Ra ≦ 0.2 μm.   The quartz wafer according to claim 1, wherein an outer peripheral edge of the flat plate is chamfered.

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