JP2009172717A - Method for manufacturing wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To process the surface of a wafer in mat finish with desired surface roughness while restricting chipping along the outer circumference of the wafer. <P>SOLUTION: Diamond paste 3 including diamond abrasive grains 3a is applied to the surface of a silicon carbide monocrystal wafer 1, and ultrasonic waves are radiated to the diamond paste 3 applied. The diamond abrasive grains 3a included in the diamond paste 3 are thus vibrated to collide with the surface of the silicon carbide monocrystal wafer 1. The surface of the silicon carbide monocrystal wafer 1 is thus processed in mat finish. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a wafer in which the surface of a wafer is processed into a satin finish.

2. Description of the Related Art Conventionally, there has been known a technique for processing a wafer surface into a satin-like shape having fine irregularities in which light diffusely reflects like ground glass by applying blast processing.
JP 2000-21786 A

  However, the matte processing by the above blast processing has a problem that chipping tends to occur on the outer periphery of the wafer. As a method for solving this problem, a method of changing blasting conditions such as processing pressure and particle size is conceivable. However, when this method is used, the surface roughness of the processed surface also changes at the same time.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress chipping on the outer periphery of the wafer and to process the surface of the wafer into a satin finish having an arbitrary surface roughness. It is to provide a method for manufacturing a wafer.

  In order to solve the above problems, a method for producing a wafer according to the present invention includes a step of applying a slurry containing abrasive grains to the surface of a wafer, and an abrasive contained in the slurry by irradiating the applied slurry with ultrasonic waves. And a step of processing the surface of the wafer into a satin-like shape by vibrating the grains and colliding with the surface of the wafer.

  According to the wafer manufacturing method of the present invention, chipping on the outer periphery of the wafer can be suppressed to an extremely low level, and the surface of the wafer can be processed into a satin finish having an arbitrary surface roughness.

  Hereinafter, a method for manufacturing a wafer according to the present invention will be described based on examples.

[Example 1]
In Example 1, as shown in FIG. 1, a φ2 inch silicon carbide single crystal wafer 1 is fixed to a wafer support 2 with wax or the like, and a diamond paste 3 containing diamond abrasive grains 3a having an average particle diameter of 6 μm is applied to a silicon carbide single crystal. By applying ultrasonic waves to the surface of the crystal wafer 1 and irradiating the applied diamond paste 3 with ultrasonic waves, the diamond abrasive grains 3 a included in the diamond paste 3 are vibrated and collided with the surface of the silicon carbide single crystal wafer 1. The surface of the silicon carbide single crystal wafer 1 was processed into a satin finish as shown in FIG. 2 with a roughness Ra (centerline average roughness) = 0.19 μm. Irradiation of ultrasonic waves is generated by the ultrasonic transducer 4, and the horn 6 that moves the ultrasonic waves amplified by the cone 5 and the horn 6 in the in-plane direction of the silicon carbide single crystal wafer 1 at a predetermined cycle and speed. It was performed by irradiating the diamond paste 3 from the tip of the above.

[Example 2]
Example 2 is the same as Example 1 except that the diamond abrasive grains 3a contained in the diamond paste 3 have an average particle diameter of 9 μm, and has a satin finish with a surface roughness Ra = 0.23 μm. The surface of the single crystal wafer 1 was processed.

[Example 3]
Example 3 is the same as Example 1 except that the diamond abrasive grains 3a contained in the diamond paste 3 have an average particle diameter of 12 μm, and has a satin finish with a surface roughness Ra = 0.33 μm. The surface of the single crystal wafer 1 was processed.

[Example 4]
Example 4 is the same as Example 1 except that the diamond abrasive grains 3a contained in the diamond paste 3 have an average particle diameter of 20 μm, and has a satin finish with a surface roughness Ra = 0.42 μm. The surface of the single crystal wafer 1 was processed.

[Comparative example]
In the comparative example, the surface of the φ2 inch silicon carbide single crystal wafer 1 is blasted using silicon carbide abrasive grains having an average particle size of 50 μm to form a satin-like silicon carbide single crystal wafer 1 having a surface roughness Ra = 0.43 μm. The surface of was processed.

[Evaluation]
Table 1 below shows the results of measuring the number of chipping defects per wafer (hereinafter referred to as defect rate) with 10 wafers for the silicon carbide single crystal wafers 1 of Examples 1 to 4 and the comparative example. In the measurement, the chipping was defined as missing 250 μm or more in the wafer radial direction or 250 μm or more in the wafer edge circumferential direction.

  As shown in Table 1, all defect rates of the silicon carbide single crystal wafers 1 of Examples 1 to 4 were 0.00. In contrast, the defect rate of the silicon carbide single crystal wafer 1 of the comparative example was 0.59. From this, the manufacturing of the wafer which applies the diamond paste 3 to the surface of the silicon carbide single crystal wafer 1 and processes the surface of the silicon carbide single crystal wafer 1 into a satin finish by irradiating the applied diamond paste 3 with ultrasonic waves. According to the method, it has been found that chipping on the outer periphery of the silicon carbide single crystal wafer 1 can be suppressed to an extremely low level and that the surface of the silicon carbide single crystal wafer 1 can be processed into a satin finish having an arbitrary surface roughness. In each of the above-described embodiments, the diamond paste 3 is used. However, the present invention is not limited to this, and the same effect can be obtained as a slurry containing silicon carbide abrasive grains or boron carbide abrasive grains.

It is a figure which shows the manufacturing method of the wafer which concerns on this invention. It is a figure which illustrates the surface of the silicon carbide single crystal wafer processed into the matte form of predetermined surface roughness with the manufacturing method of the wafer concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon carbide single crystal wafer 2 Wafer support 3 Diamond paste 3a Diamond abrasive grain 4 Ultrasonic vibrator 5 Cone 6 Horn

Claims (3)

Applying a slurry containing abrasive grains to the surface of the wafer;
And a step of oscillating the abrasive grains contained in the slurry by irradiating the slurry with ultrasonic waves and colliding with the surface of the wafer to process the surface of the wafer in a satin state. Manufacturing method.   The method for producing a wafer according to claim 1, wherein the wafer is a silicon carbide single crystal wafer.   The method for producing a wafer according to claim 1, wherein the abrasive grains are diamond abrasive grains, boron carbide abrasive grains, or silicon carbide abrasive grains.