JPH03142928A - Cutting-out of wafer - Google Patents

Abstract

PURPOSE:To contrive the improvement of the plane accuracy of the butting surface of an ingot by a method wherein when the ingot is cut into a wafer of a prescribed thickness, the cutting is performed by a cutting means in a state that an abutting means is abutted on the end surface, which is cut, of the ingot. CONSTITUTION:Each time an ingot 1 is cut into a water of a prescribed thickness, the cutting is performed by a cutting means 3 in a state that a proper abutting means 4 is abutted on the end surface, which is cut, of the ingot. Accordingly, both ends of the ingot 1 result in being supported substantially and vibrations which are generated by the drive of the means 3 and the cutting result in being dispersed equally on the side of the ingot 1 and the side of the wafer. Thereby, the cutting surface of the ingot is not formed into a waveform, the ingot does never bend as a whole and each wafer can be cut in almost parallel to the cutting surface.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method of sequentially cutting thin wafers into slices from an ingot of silicon or the like.

[Prior art]

As a method of cutting out this type of wafer, the method disclosed in, for example, Japanese Unexamined Patent Publication No. 106207/1983 is well known as a conventional example. In this conventional method, each time a wafer is cut from an ingot, the end face of the ingot is ground to make it flat, thereby increasing the flatness of one side of the cut wafer. That is, in the conventional example, as shown in FIGS. 6 and 7, a wafer b cut out from an ingot a has one side C.
However, the end face of the ingot a is ground before being cut into a flat surface, and the other face, that is, the cut face d, is still warped or uneven even on the ingot side. In other words, when the ingot a is cut by the blade e of the inner peripheral edge, the vibrations generated due to the drive and cutting of the blade are concentrated and transmitted to the thinly sliced and unsupported wafer part side, and the wafer bl
vibrates even more, and as a result, the cutting surface d becomes wavy and the entire surface is bent. Therefore, in the cut wafer b, the cut surface d is ground to make it flat in the subsequent process, and on the ingot part side, the wave-like unevenness of the cut surface d is removed by end face grinding to the position indicated by the imaginary line f. After grinding with a whetstone to make it flat, the next piece is cut out.

[Problem to be solved by the invention]

As explained in the above-mentioned conventional example, the actual situation is that the flatness of the cut surface cannot be obtained due to various conditions during cutting. In the conventional example, an attempt is made to cut out a wafer with flatness accuracy even on just one side. However, in cutting out the wafer, there is still no solution to the problem that considerable warpage or unevenness occurs on the cut surface, and therefore, removing such warpage or unevenness with a grinding wheel results in a significant waste of material. There is. When cutting a wafer, the causes of warping or unevenness on the cutting surface are that the ingot is cut in a cantilevered state, and that as the cutting progresses sequentially, the support on the free end side is lower than on the thicker ingot side. It is thought that the vibration transmission is concentrated on the thinner wafer side that is not coated, and that the thinner wafer side is weaker in strength and bends, so the cutting blade tends to tilt toward the weaker side, which causes warping or unevenness. Considering these actual circumstances, in the conventional example, there is a serious problem that must be solved in cutting out wafers from an ingot itself. [Means for Solving the 81 Problems] As a specific means for solving the problems of the conventional example, the present invention provides an appropriate abutment means for the cut end face every time an ingot is cut into a wafer of a predetermined thickness. The present invention provides a wafer cutting method characterized in that cutting is carried out by a cutting means while the wafer is in contact with the ingot, and the pre-wetting means cuts the abutting surface of the ingot by the cutting means that cuts the ingot in advance. is cut or ground so as to contact the cutting means in a state where parallelism is maintained, and the contact means is cut or ground by the cutting means that is folded at least once every time the cutting means is replaced. It is designed to cut or grind the wafer, thereby supporting and adding strength to the cut wafer.Furthermore, each time the ingot is cut into a wafer of a predetermined thickness, a predetermined cut is applied to the end face of the ingot to be cut. By attaching and cutting a plate material with a thickness of Or, the occurrence of unevenness is eliminated.

【Example】

Next, the present invention will be explained in more detail with reference to the illustrated embodiment. In the first embodiment shown in FIGS. The lower end becomes the so-called cutting end from which the wafers are successively cut out. As the cutting means 3 for this cutting, for example, a well-known doughnut-shaped blade having a cutting edge on the inner peripheral edge is used. A contact means 4 such as a turntable that comes into contact with the end surface is disposed on the end side to be cut, and the corresponding contact means 4
Cutting is performed by the cutting means 3 while the two are in contact with each other with a predetermined pressing force. In this case, the contact means 4 is
Its upper surface is cut or ground by the cutting means 3 in advance, so that the cutting means 3 and the upper surface of the abutment means 4 are positioned parallel to each other. Of course, each time the cutting means 3 is replaced with a new one, the upper surface of the abutment means 4 is cut or ground by the new cutting means 3 to obtain a flatness that matches the characteristics of the new cutting means 3. It is intended to be preserved. The contact means 4 used in ff may be made of a material such as ceramics, silicon, or aluminum, and may be a plate-shaped member corresponding to the end surface of the ingot 1, or a porous material or suction member that holds the cut wafer. It may also be a suction table provided with holes. In any case, vI! at the cut end of ingot 1! It is preferable to use a material that comes into contact with the material to absorb vibrations generated by the cutting means and has high thermal conductivity. When the abutting means 4 is brought into contact with the end face of the cutting or cutting side of the ingot 1 with a predetermined pressing force and the cutting means 3 cuts the ingot 1, a thin wafer is cut out as shown in FIG. 5 has its strength increased by the abutting means 4, and the vibrations are evenly distributed between the ingot 1 side and the wafer 5 side, so that the cut surface does not become corrugated.
It is cut in a substantially flat state. Moreover, since the side of the wafer 5 to be sliced thinly is supported by the abutting means 4 in parallel to the cutting means 3, almost no bending occurs. Further, as in the second embodiment shown in FIG. 3, in order to improve the adhesion between the abutting means 4 and the cut end of the ingot, the base 10 and the abutting means 4 are connected by a flexible joint. It's good as well. For example, a ball joint 4a is formed at the lower part of the contact means 4, and the ball joint 4a is connected to the base 1.
The abutment means 4 is rotatably received and attached at the end of 0.
When the ingot 1 contacts the end of the ingot 1, the position can be changed (by rotation) to follow the state of the end, so that the contact means 4 closely contacts the end of the ingot 1. It will become. In the third embodiment shown in FIGS. 4 and 5, instead of the abutting means 4, a plate material 6 of a predetermined thickness is integrally adhered to the cutting end surface of the ingot 1 with wax or the like for cutting. do. In other words, each time an ingot 1 is cut, a plate material 6 is attached to the end face of the ingot to perform the cutting, so that the thin wafer cut out has a thickness that substantially includes the plate material 6. As a result, the strength on the wafer side increases, the vibrations caused by the cutting means 3 are no longer concentrated on the thin wafer side, the uneven cutting is eliminated, and the cutting surface is approximately parallel and no deflection occurs as in the previous embodiment. It can be cut like this. The plate material 6 to be pasted in this case is made of a material such as silicon, aluminum, iron, or ceramics, and its thickness varies depending on the material, so it is not necessarily limited to a thickness several times that of the wafer to be cut out. It suffices if it is.

【Effect of the invention】

As explained above, in the wafer cutting method according to the present invention, each time an ingot is cut into a wafer of a predetermined thickness, the end face to be cut is brought into contact with an appropriate contact means, and then the cutter is By carrying out the cutting, both ends of the ingot are substantially supported, so that vibrations caused by driving the cutting means and cutting are evenly distributed between the ingot side and the wafer side. As a result, the cutting surface does not become corrugated, and the cutting surface can be cut almost parallel without bending, and the degree of grinding in the subsequent process is extremely low, and no extra grinding allowance is required. It has the excellent effect of being able to cut wafers to a predetermined thickness, eliminating material waste, and making it possible to cut wafers approximately 1.5 times larger than conventional methods from an ingot of the same size. . Further, the abutting means has its abutting surface cut or ground in advance by a cutting means for cutting the ingot, so that the abutting means abuts while maintaining parallelism with the cutting means, and the abutting means Each time the cutting means is replaced, the contact surface is cut or ground by a new cutting means at least once, and the wafer to be cut out is thereby supported in parallel with the cutting means and given strength. and
Similarly to the above, vibrations generated by driving the cutting means and cutting are evenly distributed between the ingot side and the wafer side, the cut surface does not become corrugated, and no bending occurs. It has the excellent effect of being able to efficiently cut out the machining material and eliminating material waste. Furthermore, each time the ingot is cut into wafers of a predetermined thickness,
By attaching a plate material with a predetermined thickness to the end face to be cut and cutting the wafer, strength is imparted to the wafer being cut, preventing concentration of vibrations and also preventing deviation of the cutting means. This eliminates the occurrence of warpage or unevenness on the cut surface, thereby achieving the same effect as described above.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a state in which the method of the first embodiment of the present invention is implemented, FIG. 2 is an explanatory diagram showing an enlarged state of cutting by the same method, and FIG. A schematic explanatory diagram of an example; FIG. 4 is an explanatory diagram showing a state in which the method of the third embodiment is carried out; FIG. 5 is an explanatory diagram showing an enlarged state of a wafer cut by the same method; FIG. 6 is an explanatory diagram showing the implementation status of the conventional example, and FIG. 7 is an explanatory diagram showing an enlarged state of a wafer cut by the conventional example. 1... Ingot 3... Cutting means 5... Wafer 2... Support member 4... Contact means 6...・Plate material

Claims (4)

[Claims] (1) A wafer cutting method characterized in that each time an ingot is cut into a wafer of a predetermined thickness, cutting is carried out by a cutting means with an appropriate contact means in contact with the end face to be cut. . (2) The abutting means has its abutting surface cut or ground by a cutting means that cuts the ingot in advance, and the abutment surface is brought into contact with the cutting means while maintaining parallelism (
1) The wafer cutting method described above. (3) The wafer cutting method according to claim 1 or 2, wherein the abutting means cuts or grinds the abutting surface with a new cutting means at least once every time the cutting means is replaced. . (4) A wafer cutting method characterized in that each time an ingot is cut into a wafer of a predetermined thickness, a plate material having a predetermined thickness is attached to the end face of the ingot to be cut.