JP2000263545A - Cutting method of silicon ingot - Google Patents

Abstract

(57) [Problem] To cut a wafer with high flatness from a silicon ingot having a diameter of 300 mm or more. A cutting method using a wire electric discharge machine for cutting a wafer from a silicon ingot.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cutting a single crystal silicon ingot used for a substrate for a semiconductor integrated circuit.

[0002]

2. Description of the Related Art Conventionally, methods of cutting a silicon ingot for cutting a wafer from a single crystal silicon ingot include an inner peripheral blade cutting method and a wire wrapping cutting method. The inner peripheral blade cutting method is a method in which an inner peripheral blade on which diamond abrasive grains are electrodeposited is rotated at a peripheral speed of about 1000 m / min, pressed against an ingot and moved in parallel with the blade surface to perform cutting. There are high features. However, the metal of the inner peripheral blade has a small thickness (often 0.3 mm or less) in order to suppress material loss at the cutting edge,
The blade must have high tensile strength to withstand uplift for achieving cutting accuracy, and the width of the blade metal must be at least three times as large as the inner peripheral diameter (greater than the workpiece diameter). For this reason, slicing of a wafer having a diameter of 200 mm or less is performed by this method, but application to slicing of a wafer having a diameter of 300 mm or more is considered difficult. That is, the size of the silicon ingot that can be cut is limited. On the other hand, wire lapping cutting is applied to slicing of a wafer having a diameter of 300 mm. In this method, silicon is wrapped and cut while applying abrasive slurry using a traveling wire as a lap tool.
Although a wire of about 15 mm is used, there is a problem that undulation occurs in the cutting direction due to lapping resistance and the flatness of the cut surface is low.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultra-precision cutting method which can exhibit a higher precision and a higher efficiency.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device having a diameter of 300 mm.
It is an object of the present invention to provide a method for cutting a silicon ingot, characterized by using a wire electric discharge machine capable of obtaining a cut surface having a good flatness which can be applied to a silicon ingot of not less than mm.

[0005]

The principle of wire electric discharge machining is that a conductive wire running in a straight line is used as one electrode, and an appropriate gap is provided between the two in an electrically insulating liquid, and a pulse voltage is impressed. In this case, a discharge is generated, and a minute portion of the workpiece is melted and scattered and removed. Therefore, since the wire and the workpiece do not directly come into solid contact with each other, the workpiece is processed into a shape following the traveling wire. FIG. 1 is a perspective view showing a cutting state of a silicon ingot according to the present invention. (1) is a silicon ingot, (2) is a wire, and (3) is a direction of wire travel. The entire silicon ingot is immersed in an electrically insulating liquid in a bathtub. The ingot is sent to the wire as much as the processing has progressed (in FIG. 1, the ingot is sent upward perpendicular to the plane of the paper). Since a brass wire having a diameter of about 0.2 mm is used for the wire, material loss at the cut is small. Since the cutting speed is low, the production efficiency can be practically improved by running the wire in parallel and cutting a plurality of places at the same time. When a silicon ingot is targeted for electrical discharge machining, the specific gravity of the electrical discharge machining debris is smaller than when steel is used as the workpiece, and it is hard to disperse and settle in the insulating liquid. Required condition. The size of the diameter of the ingot is not particularly limited up to about 400 mm. The length of the straight running portion of the wire is set larger than the diameter.

[0006]

According to the present invention, since no force is applied to the wire at the time of cutting, the cut surface is high in accuracy, and there is no restriction on the size of the diameter of the ingot that can be cut. Therefore, a wafer is cut from a silicon ingot having a diameter of 300 mm or more. be able to.

[0007]

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention.

[Explanation of symbols]

 1 Silicon ingot 2 Wire 3 Wire running direction

Claims (1)

[Claims] 1. A method for slicing a semiconductor silicon ingot into wafers, comprising using a wire electric discharge machine as a cutting device.