JPS5830137A - Manufacture of wafer - Google Patents

Abstract

PURPOSE:To obtain a wafer with uniform specific resistance by donor-killer heat treatment of a single crystal containing O more than 1.0X10<18>/cm<3> which is obtained by the CZ method, thereafter treating it at 550 deg.C-1,000 deg.C for more than 1hr. CONSTITUTION:A wafer is made from a single crystal Si containing 0 more than 1.0X10<18>/cm<3>, which is obtained by a CZ method, undergoes heat treatment at the temperature of 650 deg.C for 30-40min to eliminate donors. Then it is subject to another heat treatment at the temperature 550-1,000 deg.C to get a uniform specific resistance. The wafer is completed with chemical abrasion and mirror grinding. After this, uniform specific resistance distribution is maintained even after heating for a long time at about 1,250 deg.C. This phenomenon is specific to the wafer obtained by the CZ method: oxygen content contributes to this phenomenon. Heat lower than 550 deg.C is inappropriate because donors come into the wafer and the temperature higher than 1,000 deg.C may cause a lattice defect. Heat treatment for uniform specific resistance is effective only when it is carried out with a single crystal containing O more than 1.0X10<18>/cm<3> for more than 1hr.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wafer manufacturing method for manufacturing wafers from single crystals obtained by the Chiral Ralski method (C2 method).

Currently, the silicon materials used in the semiconductor industry have CHI! Kralski method (CZ method) and 70-ting zone method (
FZ method) There are zero types depending on K. However, in the silicon materials produced by these methods, non-uniform distribution of impurities (hereinafter referred to as striations) occurs within the crystal due to the influence of convection and rotation (seeding, rooting) during pulling. A P-type wafer made from a pulled silicon single crystal with a crystal orientation (100) and a resistivity of 40 to 60 has a resistance value measured by the wafer measurement method, as shown in Figure 1, with a unit of is (Ω). Further, the horizontal axis indicates the distance from the reference position in the diametrical direction of the wafer, and the unit is (■).

Nowadays, as device miniaturization approaches sub-micron dimensions, using wafers with such variations in resistivity distribution causes fluctuations in threshold voltage and other factors that reduce manufacturing yields. Put it away.

This invention was made in view of the above circumstances,
It is an object of the present invention to provide a wafer manufacturing method capable of manufacturing a wafer having a uniform resistivity distribution free from striations from a single crystal obtained by the C2 method.

Hereinafter, an embodiment of the present invention will be explained with reference to the drawings.

First, [C1] Yu2
Slice a 10"ys-" silicon single crystal 1,
Then, the wafer 2 was heated to 0-order K as shown in Figure 2 (03), and the wafer 2 was subjected to heat treatment (donor killer heat treatment) for eliminating oxygen donors at 650°C for 30 to 60 minutes.
・The disappearance of oxygen donors with respect to the heat treatment time is shown in the graph of Figure 3. ・From this figure, 6
It can be seen that oxygen donors are eliminated by heat treatment at 50° C. for 15 minutes or more.

The sample used to obtain the data shown in FIG. 3 is of P type, has a crystal orientation of (100), and a resistivity of 4501.

After such normal donor killer heat treatment, heat treatment is performed to make the resistivity distribution uniform (eliminating striations), which is a feature of the present application.
The process is carried out at 1000℃ for over 1 hour. After heat treatment to make the specific resistance distribution uniform, chemical polishing and surface polishing are performed to complete the wafer. When heat treatment was carried out at 650° C. for 1 hour to make the resistivity distribution uniform, the resistivity distribution as measured by the resistance measurement method after the wafer spread became K as shown in FIG. In addition, heat treatment was performed at 650°C for 2 hours, 5 hours, and 1 hour to make the resistivity distribution uniform.
The distribution of resistivity of the wafer when the test was carried out for 0 hours is as shown in FIG. 4(B), FIG. Note that the vertical and horizontal axes in FIGS. 4 (roll) to [F]) are the same as those in FIG. 1. This figure 4 η
From ) to ), it can be seen that when heat treatment is performed to make the resistivity distribution uniform after the normal donor killer heat treatment, the resistivity distribution becomes uniform.

The wafer was heat-treated at 650°C for 10 hours to make the resistivity distribution uniform.
As shown in Figure 5, even after 30 hours of high-temperature heat treatment, the uniform resistivity distribution is maintained. Therefore, even if heat treatment is performed on a wafer obtained by the FZ method, the specific i resistance distribution is not made uniform, which indicates that this is a phenomenon peculiar to wafers obtained by the C2 method.

Therefore, it is inferred that oxygen rO3] contained in the wafer obtained by the C2 method is involved in this phenomenon.

Note that the heat treatment for making the resistivity distribution uniform is as follows:
If it is less than 50°C, it is unsuitable because it is the temperature at which donors are deposited, and if it exceeds 1000°C, wafer sum lattice defects may occur. In addition, the heat treatment time for making the resistivity distribution uniform is shown in Figure 4 (kJ
As can be seen from ~(b), the effect is hardly visible unless the time is longer than 1 hour.Furthermore, the oxygen content in the single crystal pulled by the C2 method is 1゜0XI.
O''/- or more, even if heat treatment is performed to make the resistivity distribution uniform, the effect of making the resistivity distribution uniform will not clearly appear in the above embodiment.9 Therefore, the present invention In the example, a single crystal containing oxygen of 1,0 x 101 s/- or more pulled by the CZ method,
As a heat treatment to make the resistivity distribution uniform.

The test was carried out at 550°C to 1000°C for 1 hour.

As described above, according to the present invention, it is possible to provide a wafer manufacturing method capable of manufacturing a wafer having a uniform resistivity distribution free of striations from a single crystal obtained by the C2 method. can.

[Brief explanation of the drawing]

@Figure 1 is a graph showing the distribution of resistivity of a wafer obtained by the C2 method obtained by the conventional method, and Figure 2 (A) is a graph showing the distribution of resistivity of a wafer obtained by the C2 method obtained by the conventional method.
Figure 2 (CB) is a diagram showing a wafer obtained by slicing the silicon single crystal, and Figure 3 is a graph showing the effect of donor-Giller heat treatment on time. Figure 7, Figure 4 (4
) to (6) and FIG. 5 are graphs showing nine-way characteristics obtained by the manufacturing method of the present invention. 1-Silicon single crystal, 2-Way 80

Claims (3)

[Claims] (1) A method for manufacturing a wafer, which comprises a step of performing donor killer heat treatment on a single crystal obtained by the CZ method, and a step of performing heat treatment to make the resistivity uniform after the donor killer heat treatment.・ (2) The single crystal obtained by the above CZ method is 1.0×10
The method for manufacturing a wafer according to claim #I1, which is a silicon single crystal containing oxygen of /d or more◎ (3) The heat treatment to make the resistivity uniform is 5
The method for manufacturing a wafer according to claim 1, wherein the heat treatment is performed at a temperature of 50°C to 1000°C for 1 hour or more.