JPH10256196A - Marking method at beveling part of wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine a mark for crystal orientation easily without imparting residual strain into a wafer by polishing a predetermined position at the beveled circumferential fringe part of the water using a polishing butt wheel thereby making a thin shallow groove, as a mark for identifying the crystal orientation, in the beveled part. SOLUTION: A polishing butt wheel 1 pressed against a beveled part 3 while turning to make a thin shallow groove 4. Since a polishing butt wheel 1 is used for putting a mark, a groove 4 can be made slightly on the inside of the beveled part 3 with no loss of effective area of the wafer 2 nor any adverse effect, e.g. machining stress or thermal stress, on the wafer 2 body. Since a groove 4 thus made has different light reflecting state, it can be detected both visually and through use of an optical sensor and when the groove 4 is made on the surface side of the water 2, the water can be positioned from the surface side easily and visually or through an automatic system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a marking method for marking a mark used for identifying a crystal orientation on a chamfered portion of a wafer.

[0002]

2. Description of the Related Art A wafer cut from an ingot is sent to an etching process through processes such as lapping and chamfering. At this time, a mark indicating the crystal orientation of the wafer is attached to the edge of the wafer. The marks are used, for example, to scribe the cleavage plane when scribing the wafer. For conventional marking, an OF with an orientation flat at one corner of the wafer
There are employed a notch method in which a cut is made in one corner of a wafer, a laser marking method in which a wafer is melted and stamped on a wafer surface, and the like.

[0003]

However, in the OF method,
The accuracy of the crystal orientation alignment tends to be insufficient, and there is a disadvantage that the effective area of the wafer is reduced. In addition, the orientation flat restricts the shape of the electrostatic chuck used for handling the wafer, and causes a bad influence on the dynamic balance when the wafer spins. On the other hand, when the cut is made by the notch method, the processing strain tends to remain around the cut portion, and it is difficult to completely remove the remaining processing strain. Also, laser engraving has a problem with automatic reading. The present invention has been devised to solve such a problem, and by marking a chamfered portion with a polishing buff wheel, it is easy to perform either visual observation or automatic reading without giving residual distortion to the wafer. It is an object of the present invention to provide a mark for a crystal orientation that can be distinguished from a crystal orientation.

[0004]

In order to achieve the object, a marking method according to the present invention is characterized in that a predetermined position of a chamfered portion on a peripheral edge of a wafer is polished with a polishing buff wheel to obtain a thin and shallow marking for crystal orientation identification. It is characterized in that a groove is formed in the chamfer.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a polishing buff wheel similar to a buff wheel for chamfering a mirror is used. This polishing buff wheel has a buff made of polyurethane or the like adhered to the peripheral surface of a metal roll. The polishing buff wheel 1 faces the chamfered portion 3 on the peripheral edge of the wafer 2 as shown in FIG. 1, and generally has <110> ± 1 so as to have the same crystal orientation as the orientation flat or the notch.
It is positioned at a circumferential position indicating the crystal orientation such as degree.

When the polishing buff wheel 1 is pressed against the chamfered portion 3 while rotating as shown in FIG.
A shallow concave groove 4 is formed. If the depth measured as shown in FIG. 3 is 10 μm or more, the concave groove 4 is sufficiently used as a mark. When the concave groove 4 is formed in the chamfered portion 3, the effective area of the wafer 2 is not slightly impaired. The groove 4 is slightly inserted into the chamfered portion 3.
Is formed, since the marking is performed using the polishing buff wheel 1, no adverse effects such as processing distortion and thermal stress are given to the main body of the wafer 2. The concave groove 4 has a V
The bottom shape is shaped into a shape, a U shape, a trapezoidal shape, and the like.

[0007] Since the formed groove 4 has a different light reflection state, it can be determined either visually or by an optical sensor. Further, when the concave groove 4 is formed on the front side of the wafer 2,
Positioning can be easily performed from the front side of the wafer 2 visually or by an automatic device. For example, the position of the marking groove can be detected by image processing using a TV camera. Although this method can detect the position with high accuracy, it has a drawback that the equipment cost is high. Therefore, a method for detecting the reflection of a light beam that is narrowed down can be considered as an inexpensive and simple position detection method with slightly lower accuracy. That is, as shown in FIG. 4, a light beam 6 narrowed down by a slit 5 or the like is applied to the concave groove 4 from directly above the wafer 2. And
The position of the concave groove 4 is detected by detecting the light beam 6 reflected by the concave groove 4 by the light receiving element 7 arranged at a specific position.

[0008]

As described above, in the present invention, since the mark is formed on the chamfered portion of the wafer by using the polishing buff wheel, the residual processing distortion and the thermal stress do not occur with the marking. No adverse effect on the wafer body. The groove formed in the chamfered portion by the polishing buff wheel is used as a mark when aligning the crystal orientation of the wafer.

[Brief description of the drawings]

FIG. 1 is a plan view of a polishing buff wheel facing a chamfered portion of a wafer periphery.

FIG. 2 is a partial sectional view showing a positional relationship between a chamfered portion and a polishing buff wheel.

FIG. 3 is a cross-sectional view showing a chamfered portion in which a concave groove is formed by a polishing buff wheel.

FIG. 4 is a view for explaining a method for detecting the position of a groove using a light beam reflected by the groove.

[Explanation of symbols]

1: polishing buff wheel 2: wafer 3: chamfered portion 4: concave groove 5: slit 6: light beam 7: light receiving element d: depth of concave groove

Claims (1)

[Claims] 1. A method for marking a chamfered portion of a wafer, wherein a predetermined position of a chamfered portion on a peripheral edge of the wafer is polished by a polishing buff wheel, and a thin shallow groove as a crystal orientation identification marking is formed on the chamfered portion.