JPH02231110A - Cutting of columnar ingot - Google Patents

Abstract

PURPOSE:To obtain a good quality wafer by improving precision of a section, by a method wherein a dummy material is arranged on the circumference of a columnar ingot and a sectional form of a part to be processed is brought close to a square form. CONSTITUTION:Dummy materials 12a, 12b comprised of the same material with an ingot 11 or a material whose quality is resembled to that of the ingot 11 are arranged on the circumference of the ingot 11 and a sectional form of a part to be processed is brought close to a square form. Since a form of a section becomes fixed and is of a square, cutting resistance and a change of a load to a linear blade can be reduced extending from the beginning to the end and a wafer whose precision of the section is high becomes obtainable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention (Field of Industrial Application) This invention relates to a method for cutting a cylindrical ingot using a linear blade.

(American technology) Cutting silicon ingots with a saw with a linear blade has rarely been done in the past, except in some cases for manufacturing wafers for solar cells. The reason for this is that problems with the shape tend to cause uneven thickness, parallelism, and ridges or steps on the cut surface within the seam 7a.

(Problem to be solved by the invention) In order to overcome these problems, there is a conventional computer-controlled method that detects the load or estimates it by calculation from the cross-sectional shape, but at present neither of these methods lead to cutting accuracy. It is.

No matter how much the linear blade bends, the tension (Ten) of the linear blade
aion) remains unchanged. A saw using a linear blade generates a cutting load only when a vertical vector component is generated by an appropriate deflection angle l, but the unit load 1 per linear blade changes from moment to moment depending on the shape of the workpiece.

The fourth factor is an explanatory diagram showing a state of cutting by a saw equipped with a rock-shaped blade used in a conventional cutting method.

In FIG. 4, 1 is a cylindrical cylinder made of silicon or the like.The self-repairing function of the linear blade due to lateral deviation from the vertical direction varies depending on the bending angle of the linear blade and the shape of the workpiece. In other words, it has a significant effect on the corrosion of the cut surface. FIG. 5 shows the relationship of the linear blade 2 to the workpiece 1. In the figure, 3 indicates a multi-groove roller, and 0 indicates a deflection angle.

In the unidirectional linear blade running system, the deflection angle θ also differs at the entrance and exit due to the intrusion and crushing of abrasive grains, increase in chips, etc. That is, the load on the linear blade 2 is also different.

In addition, the tangential load of a linear blade changes depending on the particle size of the abrasive grains (different between new and old ones), viscosity of oil, specific gravity, increase in chips, etc., so the shape calculation value method takes into account all of these factors. It is impossible to incorporate factors.

The present invention was made to solve the above-mentioned problems, and it is an object to provide a method for cutting a cylindrical ingot, which allows obtaining wafers of high quality with high precision of the cut surface.

[Structure of the Invention] (Means for Solving the Problems) n A cutting method characterized in that a dummy material is arranged around a cylindrical ingot so that the cross-sectional shape of the processed part approaches a square shape. It is.

(Function) Since the cutting method of this invention makes the cross-sectional shape of the workpiece close to a square shape, the cutting surface is constant and the cutting resistance and linear cutting edge are constant from the beginning to the end, just like in the case of a square workpiece. It is possible to reduce the change in the load against the load. Therefore, stable cutting accuracy can be obtained, and a wafer with a highly accurate cut surface can be obtained.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The relationship between the work l, the linear blade unit, and the multi-groove roller 1 is almost the same as that of the fourth roller, but the first
As shown in the figure, dummy materials 12m and 12b made of the same material as that of the ingot 11 or materials with similar properties are placed around the cylindrical ingot 11, so that the cross-sectional shape of the workpiece is made into a rectangular shape. Let's go.

In Figure 1, the dummy materials 12m and 12b are arranged on both sides of the cylindrical ingot 11, but it is also possible to arrange the dummy materials 12a and 12b on the upper and lower sides as shown in Figure 2. .

When the configuration shown in Figure 1 or wJz diagram is adopted, the shape of the cut surface is constant and square, so the change in cutting resistance and load on the linear blade can be kept at least Q from the beginning to the end of the cutting operation. Therefore, a wafer with a highly accurate cut surface can be obtained.

! 1 and 2 show the case where one cylindrical ingot 11 is to be processed, but when there are two ingots, a configuration as shown in FIG. 3 can be adopted.

As shown by the line, the ζ-dami material 22e. 22d can also be placed on both sides.

However, cutting silicon ingots for semiconductors with a saw using a linear blade has the advantage that, unlike other boring and lapping processes that involve pressing loose abrasive grains, the processing fracture layer and crystallographic damage are extremely small.

Therefore, as long as the cutting accuracy (particularly the undulations) can be maintained, the next step of lapping, and in some cases even boring, can be omitted as in normal wafer manufacturing. The machining allowance and cutting allowance of the damaged layer are 0. 3 mm
．． Compared to this, the dummy material is made of a material that has properties similar to the diameter of the linear blade, and by adopting this configuration, it is possible to efficiently obtain wafers with high precision.

Note that it has the advantage of being able to be further broken to increase the precision of the cut surface.

FIG. 6(1) shows the cut surface of a silicon single crystal round ingot cut by a conventional method, as measured by a surface roughness meter.

Figure 6fb) is the ingot as shown in Figure 1.
The cut surface obtained when cutting with the dummy materials 12a and 12b provided is measured at the surface Jt.

By comparing FIG. 6f&) and fb)t, it can be seen that the accuracy of the cut surface is significantly improved when the method according to the present invention is used.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and may have different configurations without changing the spirit of the invention.

[Effects of the Invention] According to the present invention, it is possible to provide a method for cutting a cylindrical ingot, which allows obtaining wafers of high quality with high precision of the cut surface.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a workpiece according to an embodiment of the present invention, FIG. 2 is a sectional view showing the structure of a workpiece according to another embodiment of the invention, and FIG. 3 is a sectional view showing the structure of a workpiece according to another embodiment of the invention. 4 is an explanatory diagram showing the cutting state in the case of a saw equipped with a linear blade used in the conventional cutting method. FIG. 5 is a sectional view showing the structure of the workpiece part of the embodiment. Figure 6 (&) is an explanatory diagram of the deflection angle of a linear blade in a silicon single crystal round ingot. fb) is a characteristic diagram when the same ingot was cut according to the first embodiment of the present invention and the cut surface was measured using a gold surface roughness meter. 1.11.21m, 2lb-cylindrical ingot 2...
Linear blade 3...Multi-groove rollers 12a, 12b, 22a"! 2d - Dummy material procedure correction writing method) Figure Fumi Takeshi Yoshida, Commissioner of the Patent Office l. Indication of the case Patent Application No. 1-53251 2. Name of the invention Method for cutting cylindrical ingots 3. Relationship with the case of the person making the amendment Patent applicant M Setec Co., Ltd. 4. Agent address 11fl7T Nishikan, Ota-ku, Tokyo [l 5 0-3 ■1
Village Building 319} Figure 5. Date of amendment order (shipment date) May 308, 1999 7. Contents of amendment (1) Submit the document certifying the power of attorney (power of attorney) as is. (2) Add Figure 6 (a) to the drawings attached to the application as shown in the attached sheet. Attachment C b Applicant M Setec Co., Ltd.

Claims (1)

[Claims] A method for cutting a cylindrical ingot using a linear blade stretched between rollers, which is characterized by arranging a dummy material around the cylindrical ingot so that the cross-sectional shape of the processed part approaches a square shape. How to cut an ingot.