JP2005231248A - Single crystal cutting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting method of a single crystal capable of cutting out and separating a wafer having no camber without a preliminary test. <P>SOLUTION: A crystal direction is beforehand determined by slicing a single crystal ingot having a crystal direction of <111> parallel to the direction of the crystal habit line. By this the wafer having very little bend and camber can be cut out and separated only by adjusting a cutting direction of a cutter to the direction of the crystal habit line. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a single crystal cutting method for obtaining a wafer by cutting a semiconductor single crystal ingot with a cutting machine (slicing machine).
Specifically, the present invention relates to a single crystal cutting method for slicing a single crystal ingot along a predetermined cutting plane by causing the cutting machine to cut into the single crystal ingot while relatively moving the single crystal ingot and the cutting machine.

  Conventionally, as a single crystal cutting method of this kind, a plurality of cutting positions where the slicing easily proceeds by a preliminary test (zone slicing test) and the rotation direction of the cutting machine at each cutting position are set, and the cutting position and cutting are set. There is one in which bending or warping of a cut wafer is prevented by slicing a single crystal ingot (single crystal member) while switching the rotation direction of the machine (see, for example, Patent Document 1).

Japanese Patent Publication No. 1-15363 (page 1-4, FIG. 1 to FIG. 3)

  However, in such a conventional single crystal cutting method, workability is poor, such as requiring a lot of time for a preliminary test for setting the ingot cutting position, and the apparatus becomes expensive. There were so many problems.

An object of the present invention is to provide a single crystal cutting method capable of cutting and separating a wafer without warping without a preliminary test.
In addition to the object of the invention described in claim 1, the invention described in claim 2 aims to efficiently slice a large-diameter wafer.

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention is characterized in that the crystal orientation of the single crystal ingot is <111> and sliced parallel to the direction of the crystal habit line. It is.
The invention described in claim 2 is characterized in that a configuration in which the cutting machine is a wire saw cutting machine is added to the configuration of the invention described in claim 1.

According to the first aspect of the present invention, the crystal orientation of the single crystal ingot is determined in advance by slicing a single crystal ingot having a crystal orientation of <111> in parallel with the direction of the crystal habit line. By simply aligning the cutting direction of the cutting machine with the direction of the crystal habit line, a wafer with very little bending or warping can be cut and separated.
Therefore, cutting efficiency can be remarkably improved as compared with the conventional method requiring a preliminary test.

In addition to the effect of the invention of claim 1, the invention of claim 2 uses a wire saw as a cutting machine to efficiently slice a large number of wafers at a time even with a large-diameter single crystal ingot. be able to.
Therefore, a large-diameter wafer can be sliced efficiently.

An embodiment of the present invention will be described below.
In this example, a cylindrical silicon single crystal ingot grown so that the crystal orientation is <111> is set on a holding jig with its axial direction oriented horizontally, and the axial direction of this single crystal ingot is A wire saw is provided as a cutting machine for cutting in the intersecting direction, and either or both of the wire saw and the single crystal ingot are relatively parallel to the direction of the habit line of the single crystal ingot which is the cutting direction. This shows a case where the wafer is cut and separated by slicing in the radial direction by moving the wafer closer to the position.

  The wire saw is a multi-wire saw having a conventionally well-known structure, and is arranged at equal intervals in the axial direction of the single crystal ingot, and by continuously moving all of them, a large number of wafers can be simultaneously sliced. Yes.

  Then, using the wire saw, the single crystal ingot having a crystal orientation of <111> is sliced parallel to the direction of the crystal habit line by the above-described single crystal cutting method, and the bending generated in these wafers is obtained. FIG. 1A shows the results of measuring the number of occurrences of bending and warping and the respective deformation amounts in order to investigate the warping and warping.

  Furthermore, for comparison, the number of occurrences of bending and warping and the amount of deformation were also measured for wafers obtained by slicing a single crystal ingot with the same wire saw regardless of crystal orientation and habit line. The results are shown in FIG.

  1 (a) and 1 (b) show the relative frequency (Frequency:%) as the number of occurrences of bending and warping of all wafers, and the surface roughness (waviness WCM value) as the deformation amount of each wafer. : Μm) is a graph with the horizontal axis.

  As a result, the average value (Average) of the wafer obtained by slicing in parallel with the direction of the crystal habit line shown in FIG. 1A is independent of the crystal orientation and the habit line shown in FIG. The average deviation of the wafer obtained by slicing is about ½, and the standard deviation shown in FIG. 1A is about 1 compared to the standard deviation shown in FIG. / 3.

  Thereby, the wafer obtained by slicing parallel to the direction of the crystal habit line shown in FIG. 1A is the wafer obtained by slicing regardless of the crystal orientation and the habit line shown in FIG. It can be seen that the variation in bending and warping is significantly reduced.

  The reason why such a result was obtained is that, in a macro silicon single crystal ingot, the (111) plane is usually a cleavage plane, and the slice direction is along the crystal habit line generated by the difference in the degree of crystal plane development. By correcting this, it is considered that an ideal cut is obtained in which bending and warping hardly occur in the cut wafer.

  In addition, although the case where a wire saw was used as a cutting machine was shown in the previous embodiment, the present invention is not limited to this, and a band saw or a blade may be used instead of the wire saw. Results are obtained.

(A) is a graph which shows the result of the single crystal cutting method which shows one Example of this invention, (b) is a graph which shows the result by the conventional single crystal cutting method.

Claims (2)

In the single crystal cutting method of slicing the single crystal ingot along the planned cutting plane by cutting the cutting machine into the single crystal ingot while relatively moving the single crystal ingot and the cutting machine,
A single crystal cutting method, characterized in that the crystal orientation of the single crystal ingot is <111> and sliced parallel to the direction of the crystal habit line. The single crystal cutting method according to claim 1, wherein the cutting machine is a wire saw cutting machine.

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