JPH0146235B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing semiconductor wafers.

[Prior art] Semiconductor single crystal ingots are produced using the conventionally known horizontal Bridgeman method (H・B method) and temperature gradient method (G・F method).
method), Czyochralski method (C.Z method), etc.

This semiconductor single crystal was cut into an ingot using a laser beam.

Conventionally, this laser beam was irradiated onto a semiconductor single crystal ingot only from one side.
To exaggerate the situation, as shown in FIG. 1, the thickness of the wafer was uneven between one end and the other end.

In FIG. 1, 11 is a wafer and 12 is a cutting margin.

If the thickness of the wafer is thus non-uniform, a considerable amount must be removed by polishing in order to make the thickness of the wafer uniform in a subsequent polishing process, resulting in a lot of waste.

Incidentally, Japanese Patent Laid-Open Nos. 50-64898 and 1982-114669 have proposed a method of cutting a semiconductor wafer into individual chips using a laser beam. However, when these methods are applied to cutting ingots, the following problems occur. That is, in both of the above methods, the wafer is cut by irradiating the portion of the wafer to be cut with laser beams from above and below simultaneously or alternately so that the cut surface is formed by two laser beams. However, when this method is applied to cutting an ingot, both surfaces of the wafer obtained by cutting become convex. In this case, when a wafer with convex surfaces like this is fixed to a jig for polishing, the wafer is fixed in an inclined position, which not only prevents good polishing but also causes the wafer to crack. There's a problem.

SUMMARY OF THE INVENTION In view of this situation, it is an object of the present invention to provide a method of manufacturing a semiconductor wafer that can produce a wafer with a flat cut surface and a uniform thickness without waste.

[Summary of the Invention] The gist of the present invention is to provide a method for producing a plurality of semiconductor wafers by irradiating a straight body of a semiconductor single crystal ingot with a laser beam to cut the ingot, and in which a plurality of semiconductor wafers are manufactured by cutting the ingot. arranging at least one laser beam irradiation device on each side, and irradiating the ingot with laser beams in two directions from both sides of the ingot so that the respective laser beams irradiated from the irradiation devices on both sides do not collide; One surface of both surfaces of the semiconductor wafer obtained is formed by cutting only with a laser beam from one of the two directions, and the other surface of the semiconductor wafer obtained is formed by cutting the other surface of the semiconductor wafer. It is formed by cutting only with a laser beam from the direction.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 2 is an explanatory diagram showing one embodiment of the present invention, in which 21 is a semiconductor single crystal ingot, and 23 is an irradiation device 23 arranged to irradiate the outer periphery of the straight body of the ingot 21 with a laser beam from both sides thereof. It is. Although FIG. 2 shows that there are three laser beam irradiation devices 23, they can be moved as appropriate, so there may be one or two, or there may be four or more. It's okay.

In reality, it seems economical to arrange two machines, one on each side, and perform irradiation and cutting alternately.

Further, each of the irradiation devices 23 is arranged so that the laser beams 22 to be irradiated do not collide with each other.

In this way, the laser beam 2 is applied to the ingot 21.
3, each laser beam 23 emitted from each irradiation device 23 can cut the ingot 21 without colliding with each other, and one side of the resulting wafer 31 is irradiated from one side as shown in FIG. It is formed by cutting with the laser beam 23, and the other side is formed by cutting with the laser beam 23 irradiated from the other side. In addition, 32
is the cutting allowance. Each cut surface of the wafer 31 thus obtained is formed by cutting with a laser beam in one direction, so it is flat, and each surface of the wafer 31 is formed by cutting with a laser beam 23 in an opposite direction. Because of this, the thickness is uniform. Therefore, when polishing the obtained wafer 31, since both surfaces of the wafer are flat and the thickness is uniform,
Good polishing is possible without the wafer tilting and being fixed to the jig, and the amount of polishing can be reduced.

Furthermore, since the spacing between the irradiation devices 22 can be smaller than in the conventional method of irradiating from one direction, more wafers can be obtained from one ingot 21, and there is no waste.

[Effects of the Invention] As explained above, with the wafer manufacturing method of the present invention, wafers with flat cut surfaces and uniform thickness can be obtained, and furthermore, a large number of wafers can be manufactured from the same ingot compared to the conventional method. The effect is that the wafer can be cut out and there is no waste.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a wafer and a cutting margin according to a conventional manufacturing method, FIG. 2 is an explanatory diagram showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram showing a wafer and a cutting margin according to an embodiment of the present invention. FIG. 21: Ingot, 22: Laser beam, 23:
Irradiation device, 31: wafer, 32: cutting allowance.

Claims (1)

[Claims] 1. In a method of manufacturing a plurality of semiconductor wafers by irradiating a straight body of a semiconductor single crystal ingot with a laser beam to cut the ingot, at least one laser beam is provided on each side of the straight body of the ingot. By arranging a light irradiation device and irradiating the ingot with laser beams in two directions from both sides of the ingot so that the respective laser beams irradiated from the irradiation devices on both sides do not collide, one of the two surfaces of the semiconductor wafer to be cut is One surface is formed by cutting only with a laser beam from one of the two directions, and the other surface of the obtained semiconductor wafer is formed by cutting only with a laser beam from the other direction. 1. A method for manufacturing a semiconductor wafer, comprising forming the semiconductor wafer by cutting.