JPH02155231A - Manufacture of wafer - Google Patents

Abstract

PURPOSE:To reduce the production time and cost by forming periodic irregularities to the outer circumference of an ingot, slicing the ingot in recessed sections and dividing the ingot into wafers. CONSTITUTION:Protruding sections 2 are shaped so as to execute the beveling working of wafers by using a specified jig (a grinding stone). It is favorable that the surfaces 3 of the adjacent sections of the protruding sections 2 are part of the surface of a column centering around the axis of an ingot 1-that is, the surfaces 3 are made approximately parallel with the axis of the ingot. It is because the deviation and warpage of the blade (the grinding stone) at the time of slicing are avoided. The ingot 1, the outer circumference of which is ground, is sliced by a known cutter into wafers 5. When the positions S of cutting are determined on the slicing, the protruding bodies 2 are used as alignment marks. Accordingly, the positional errors of slicing are inhibited at a small value, thus equalizing the thickness of the wafers 5 after slicing in the whole wafers.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a wafer manufacturing method, more specifically, to an improvement in the processing process of grinding and slicing semiconductor ingots into wafers by reducing the number of steps in the wafer manufacturing process. For the purpose of reducing time and cost and making the wafer thickness more uniform during slicing, periodic irregularities are formed on the outer periphery of the ingot in the outer periphery grinding process of the ingot before the ingot slicing process, The ingot is configured to be sliced into wafers in the recess.

[Industrial application field]

The present invention relates to a method for manufacturing a wafer, and more particularly, to an improvement in the process of grinding and slicing a semiconductor ingot into a wafer.

[Conventional technology]

Semiconductor materials such as silicon, GaAs, and InP are made into wafers in the process of manufacturing semiconductor devices such as ICs and LSIs from their ingots. A conventional wafer manufacturing process usually consists of the following steps (a) to (g).

(A) Production of crystal ingot; (B) Grinding of the outer periphery of the ingot; (1) Slicing of the ingot; (I) Chamfering of the wafer (grinding of the outer periphery): (1)
wafer lapping; (force) wafer etching; and (g) wafer polishing.

By performing the above-mentioned chamfering process, it is possible to prevent or prevent chipping of the wafer edge, to prevent the occurrence of shrimp crowns during epitaxial growth, and to prevent swelling around the resist layer due to spin coating.

[Problem to be solved by the invention]

In the conventional process, the outer periphery grinding process is performed twice, once for ingots and once for wafers.

It is an object of the present invention to reduce the number of steps in the wafer manufacturing process to reduce manufacturing time and cost and to provide more uniform wafer thickness during slicing.

[Means to solve the problem]

The above-mentioned object is characterized in that in the step of grinding the outer periphery of the ingot before the step of slicing the ingot, periodic irregularities are formed on the outer periphery of the ingot, and the ingot is sliced in the recesses and divided into wafers. This is achieved by a wafer manufacturing method.

[For production]

In the present invention, the wafer is chamfered when the outer periphery of the ingot is ground, and the convex parts (protrusions) from this chamfering can be used as position detection marks during slicing, which improves the cutting accuracy (i.e. , wafer thickness accuracy).

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described in detail below with reference to the drawings, while comparing the sea urchin production method according to the present invention with a conventional method.

Wafers are manufactured according to the following steps.

(a) Production of crystal ingot (see Figure 8).

An ingot 1 of a semiconductor such as Si, GaAs, InP or quartz glass is made by a known method such as the CZ method. The cylindrical surface of the ingot 1 has wave-like irregularities in the longitudinal section. Then, both ends of the ingot are cut.

(b) Grinding the outer periphery of the ingot (see Figures 1A, 1B, 2A, and 2B).

In the present invention, as shown in FIGS. 1A and 1B, when grinding the outer periphery of the ingot 1, a predetermined jig (grinding wheel) is used.
A convex portion (protrusion) 2 is formed so that the wafer is chamfered using a wafer. As shown in FIG. 1B, the projection 2
It is preferable that the surface 3 of the adjacent portion is part of a cylindrical surface centered on the central axis of the ingot 1, in short,
Surface 3 is approximately parallel to the central axis of the ingot. This is to avoid deviation or warping of the blade (grindstone) during slicing.

Conventionally, as shown in FIGS. 2A and 2B, the outer periphery of the ingot 1 is ground into a cylindrical shape, so that the outer periphery surface 4 of the ingot is substantially parallel to the central axis of the ingot and is flat.

(1) Ingot slicing (Fig. 3A, 3B)
4A and 4B).

In the present invention, as shown in FIGS. 3A and 3B, an ingot 1 whose outer periphery has been ground is sliced into wafers 5 using a known cutting machine (for example, a slicing machine using an internal grindstone). During this slicing, when determining the slicing (cutting) position S in FIG. 1B, the protrusion 2 is used as a positioning mark. Therefore, the slicing position error can be suppressed to a small value, and the thickness of the wafers 5 after slicing can be made uniform over all the wafers. As shown in FIG. 3B, there is a protrusion 2 on the outer peripheral edge of the obtained wafer 5, which forms the chamfered end face of each wafer.

Conventionally, as shown in FIGS. 4A and 4B, an ingot 1 is sliced to obtain a wafer X6, and the end face of each wafer is approximately perpendicular to the slicing plane as shown in FIG. 4B. In this case, since there is no positioning mark during slicing, the slicing position error becomes large, and the thickness of the wafer after slicing is uneven when viewed from the total number of wafers. For this reason, in order to make the wafer thickness a predetermined value, it is necessary to process the wafer surface by increasing the machining allowance in a subsequent process. This results in wasted material in machining time and machining allowances.

(1) Wafer chamfering (see Figures 5A and 5B) In the present invention, wafer chamfering (grinding) is not necessary, and in the conventional example, as shown in Figure 5B, wafer chamfering (grinding) A chamfer 7 is applied to the wafer 6.

(e) Wafer lapping (see Figures 6A and 6B) Lapping is performed to smooth the wafer surface to eliminate unevenness caused by slicing, and in the present invention,
A part of the cylindrical surface adjacent to the protrusion 2 on the end face of the wafer 5 (a surface approximately flat with the ingot central axis) is also shaved at the same time, and the entire end face is chamfered 8 as shown in FIG. 6B. .

Conventionally, the unevenness on the surface of the wafer 5 is similarly smoothed by lapping, and the chamfered portion is the same as in the present invention, as shown in FIG. 6B.

(Force) Wafer etching and polishing (see Figure 7).

In the present invention and in the prior art, wafers can be manufactured by etching the wafer 4.5 to remove the layer damaged by lapping, and polishing the wafer surface to a mirror surface 9.

〔Effect of the invention〕

As described above, according to the present invention, the conventional two steps of outer circumferential grinding and chamfer grinding can be performed simultaneously in the ingot outer circumferential grinding process, thereby reducing the number of steps during wafer manufacturing. Furthermore, the convex portion (
Since the protrusions) can be used as positioning marks during slicing, variations in thickness between wafers can be reduced even when slicing a large number of wafers. For these reasons, the present invention can reduce the time and cost in manufacturing wafers.

[Brief explanation of the drawing]

FIG. 1A is a schematic cross-sectional view of an ingot in the ingot outer circumferential grinding process in wafer manufacturing according to the present invention, FIG. 1B is an enlarged cross-sectional view of the surface portion of the ingot in FIG. 1, and FIG. 2A is a FIG. 2B is an enlarged sectional view of the surface portion of the ingot in FIG. 2A, and FIG. 3A is a schematic sectional view of a sliced wafer according to the present invention. 3B is an enlarged sectional view of the edge of the wafer in FIG. 3A, FIG. 4A is a schematic sectional view of a conventionally sliced wafer, and FIG. 4B is an enlarged sectional view of the edge of the wafer in FIG. 4A. FIG. 5A is a schematic cross-sectional view of a conventional chamfer-ground wafer, FIG. 5B is an enlarged cross-sectional view of the edge of the wafer in FIG. 5A, and FIG. FIG. 6B is an enlarged cross-sectional view of the edge of the wafer in FIG. 6A; FIG. 7 is a schematic cross-section of a wafer etched and polished according to the present invention and conventionally; FIG. FIG. 8 is a schematic cross-sectional view of a crystal ingot. ■...Ingot, 2...Convex part (protrusion), 5
．． 6... Wafer 7. End... Chamfering.

Claims (1)

[Claims] 1. In the step of grinding the outer periphery of the ingot before the step of slicing the ingot, periodic irregularities are formed on the outer periphery of the ingot, and the ingot is sliced at the recesses to be divided into wafers. Characteristic wafer manufacturing method.