JP2002283340A - Ingot cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an economical ingot cutting method by preventing the occurrence of a wafer crack due to the vibration of the wafer itself during cutting, which has become increasingly conspicuous along with increase in wafer bore diameter, and keeping the yield of the wafer above a desired level. SOLUTION: An ingot 1 is fixed at a fixing means of a cutting device in such a way that the cleavage plane 3 of the ingot 1 is out of parallel with a plane formed by a row of wires 5 which constitute a wire saw and then cut.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for cutting an ingot, and more particularly to a method for cutting a single-crystal silicon ingot having a large diameter of 20 cm or more.

[0002]

2. Description of the Related Art As a technique for preventing cracking and dropping during cutting of an ingot, there is a method of making a curvature of an ingot contact surface portion of a beam smaller than that of an ingot. However, when the ingot is cut by a method in which the curvature of the ingot contact surface portion is made smaller than that of the ingot, mechanical vibration of the ingot cutting device itself, vibration due to running of the wire, vibration accompanying the cutting operation, and the like occur. It is known. These vibrations are transmitted to the ingot and urge the cutting wafer to vibrate, sometimes causing the wafer to crack. However, when the diameter of the ingot is not very large, the vibration itself does not become so large, so that the frequency of occurrence is low, and the present situation is that the vibration itself is left without any special measures. However, with the sophistication of integration,
With the advent of larger wafers, such cutting phenomena have become significant.

[0003]

SUMMARY OF THE INVENTION As described above, the present invention prevents wafer cracking due to vibration of the wafer itself at the time of cutting, which has become apparent due to the large diameter of the wafer, and provides a desired wafer yield. It is an object of the present invention to provide a more economical method for cutting an ingot by keeping it at a level or higher.

[0004]

Means for Solving the Problems The present inventors have conducted various studies to achieve the above-mentioned object, and as a result, the ingot has a non-open surface with respect to a surface formed by a wire row constituting a wire saw. The inventors have found that the above-mentioned problems can be solved by fixing the ingot to the fixing means of the cutting device so as to be parallel, and cutting the ingot, thereby completing the present invention.

That is, according to the present invention, the diameter is 15 cm
Or more, preferably 20 cm or more, more preferably 30 cm or more.
cm or more when cutting a single crystal silicon ingot used to obtain a wafer having a so-called large diameter
An ingot cutting method is provided in which the ingot is fixed to fixing means of a cutting device and cut so that the open surface of the ingot is non-parallel to the surface formed by the wire rows constituting the wire saw. .

Further, in the above cutting method, a method of fixing and cutting the ingot so that the angle formed by the surface formed by the wire rows and the open surface of the ingot is a maximum angle to an angle close to the maximum angle. Is provided. In this specification, an angle close to the maximum angle is usually 4
An angle of 0 degree or more. Furthermore, when a single crystal silicon ingot is cut to obtain a silicon wafer having a {100} plane, the {11}, which is the open face of the ingot, is obtained.
An ingot cutting method is provided, wherein the ingot is fixed to fixing means of a cutting device and cut so that the angle formed by the 0 ° plane and the surface formed by the wire row is preferably in the range of 10 to 45 degrees.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The ingot 1 is fixed via the beam 2 in the state shown in FIG. 2 during normal cutting, and therefore, during cutting, the wafer 9 is mainly , Vibrations parallel and perpendicular to the vibration are applied. The vibration perpendicular to the plane portion of the wafer 9 causes the surface 6 which is a portion cut from the ingot 1 of the wafer 9 to be a node in the vibration of the wafer 9, so that the largest distortion occurs there. Here, the node refers to a position where the vibration wave becomes 0, and the surface 6 becomes a 0 point at the time of cutting. In addition, the surface 6 refers to a surface formed by the wire row 5 including the series of wires 4 illustrated in FIG. It has been known that cracking of a silicon wafer is likely to occur along a wall opening surface. However, conventionally, when a single crystal silicon ingot is cut, vibration perpendicular to a plane portion of the wafer 9 is caused by cutting. Due to the small diameter of the ingot, the vibration was small, the resulting strain was small, and the silicon wafer was hardly cracked during cutting of the single crystal silicon ingot. The method for cutting an ingot according to the present invention is applicable not only to single crystal silicon but also to other ingots such as single crystal GaAs.

Therefore, when manufacturing a large-diameter single-crystal silicon or the like, the plane of the ingot is parallel to the plane that becomes a node of vibration of the wafer, that is, the plane formed by the row of wires. By fixing the ingot to the fixing means of the cutting device at an angle that does not make it inconsistent, and performing cutting, it has been found that cracking of the wafer at the time of cutting the ingot, which tends to occur along the open surface of the ingot, can be efficiently prevented. If the open surface of the ingot is not parallel to the surface formed by the wire row, cracking of the wafer during cutting can be prevented, but on the surface of the cut wafer,
As shown in FIG. 3, in the silicon wafer having the {100} plane 7, the {110} plane 8, which is the open face of the silicon wafer,
Since they exist in a mutually orthogonal shape, when cutting the ingot, hold the ingot against the surface formed by the wire row so as to be as evenly separated from the mutually open walled surfaces as possible Is preferred. In addition, in this specification, when simply pointing to a beveled surface, it is indicated by using 3 as a code, and when pointing to a {110} surface, a code is used as 8 Is displayed.

[0009] More specifically, the angle of the open surface of the single crystal silicon ingot farthest from the surface formed by the wire row, that is, the open surface of the single crystal silicon ingot is Most preferably, it is fixed at 45 degrees. Of course, when the ingot is cut in such a state, the effect is maximized.
Even if it is not a degree, even if it is fixed at an angle of at least 10 degrees, preferably at least 40 degrees, almost the same crack prevention effect can be obtained.

Hereinafter, a cutting method according to the present invention will be described.
This will be described in more detail with reference to the drawings and embodiments. Figure 1
1 is a drawing schematically showing the relative positions of a wire saw and an ingot in one embodiment of the ingot cutting method according to the present invention. In this case, the surface 6 (not shown) formed by the wire rows 5 and the open surface 3 of the ingot are held at approximately 45 degrees.

[0011]

EXAMPLES (Examples and Comparative Examples) A single-crystal silicon ingot is cut at various angles from 0 to 45 degrees with respect to a plane formed by a row of wires constituting a wire saw. The average cracks per ingot and the average number of drops per ingot when fixed to the fixing means of the apparatus and cut were tested. In the example shown in FIG. 1, the wall 3 is a {110} plane 8, which is perpendicular to the wafer surface and formed from the wall 3 and the wire array 5. The angle formed by the surface 6 (not shown) is maintained at the maximum value of 45 degrees. FIG. 4 schematically shows an example of cutting when the ingot is held at the minimum angle of 0 degrees between the open wall surface 8 and the surface formed by the wire row. , Corresponding to a comparative example.

The angle between the open surface 3 and the surface formed by the wire row 5 is set to an angle at which the open surface 3 of the ingot is parallel to the surface formed by the wire row 5. The fixed angle is fixed at various angles between 45 degrees at which the angle between the two when the beveled surface 3 and the same surface are held non-parallel from a certain 0 degree is 45 degrees, and the ingot 1 is cut. The average cracks and the average number of dropped wafers per ingot were tested. FIG. 5 is a graph showing the results as relative values. In addition, the result shown in FIG. 5 is shown as a result summarized in groups every 10 degrees.

FIG. 5 is a graph showing an average crack of a wafer per ingot and an average number of dropped wafers. As is clear from this graph, when the angle between the open wall and the surface formed by the wire row is less than 10 degrees, the average crack and the average number of dropped sheets become maximum. The value in this case is 1
00, 1 in the range of 10 degrees or more and less than 20 degrees
5.0, 11.7, 3 in the range of 20 degrees or more and less than 30 degrees
In the range of 0 degree or more and less than 40 degrees, the average crack and the average number of dropped sheets are 24.0, which are significantly reduced. Further, in the range of 40 to 45 degrees, neither cracking nor dropping of the wafer was observed.
In other words, it can be seen that when the cut surface is cut in parallel with the open surface and the surface formed by the wire row, the cracking and dropping of the wafer increases, and by fixing the wafer non-parallel and cutting, the cracking and dropping of the wafer can be prevented.

[0014]

As described above, the ingot is fixed to the fixing means of the cutting device so that the open surface of the ingot is not parallel to the surface formed by the wire rows constituting the wire saw, and cutting is performed. By doing so, it is possible to prevent the wafer from being cracked and dropped during cutting. Thus, according to the present invention, a wafer can be manufactured with a very high yield.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of an ingot cutting method using a wire saw according to the present invention.

FIG. 2 is a cross-sectional view schematically showing a state of an ingot during cutting.

FIG. 3 is a front view of the wafer showing a positional relationship between a silicon wafer having a {100} plane and a {110} plane which is a fully open surface thereof.

FIG. 4 is a schematic diagram showing the positional relationship between the beam and the open face of the ingot when the silicon ingot having the {100} plane is cut at an angle of 0 ° between the wire row and the open face of the wall.

FIG. 5 is a graph showing a relationship between an angle at the time of cutting a silicon ingot having a {100} plane and a drop and crack of a wafer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ingot, 2 ... Beam, 3 ... Open surface of ingot, 4 ... Wire, 5 ... Wire row, 6 ... Surface formed by wire row when cutting ingot, 7 ...
{100} plane, 8 ... {110} plane, 9 ... wafer.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3C058 AB03 AB04 BA02 BA07 CA01 CB02 CB03 CB05 DA03 3C069 AA01 BA06 BB03 CA04 EA02 EA05

Claims (3)

[Claims] 1. A method for cutting an ingot, comprising: fixing the ingot so that a surface formed by a wire row of a wire saw and a open surface of the ingot are not parallel to each other; and cutting the ingot. . 2. The ingot is fixed so that an angle formed between a surface formed by a wire row of a wire saw and a wall of the ingot is a maximum angle to an angle close to the maximum angle. Cutting method described in 1. 3. The ingot to be cut is a single crystal silicon, and the single crystal silicon ingot is cut into {100}.
When a silicon wafer having a surface is obtained, an angle between a {110} surface, which is the open surface of the silicon ingot, and the surface formed by the wire row is fixed in a range of 10 degrees to 45 degrees. The cutting method according to claim 1.