Semiconductor wafer heat treatment method

Details Semiconductor wafer heat treatment method Semiconductor wafer heat treatment method

1993-05-13

1995-01-31

Kunemund, Robert

Single-crystal, oriented-crystal, and epitaxy growth processes;

Processes of growth with a subsequent step acting on the...

117 13, 117930, 437 10, C30B 102

Patent

active

053851153

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a heat treatment method of semiconductor wafers, particularly a wafer obtained by slicing a silicon single crystal produced by a pulling method, and more particularly to a technique for controlling the precipitation amount of oxygen in the wafer by changing the conditions of "heat treatment causing oxygen precipitation nucleus" (hereinafter referred to as the IG heat treatment) in correspondence to quantity of thermal donors in the crystal directly after being pulled.


BACKGROUND ART

In producing a silicon single crystal, for example, by a pulling method, since a crucible for containing melt of a material is usually made of quartz, oxygen of about 10.times.10.sup.17 -20.times.10.sup.17 atoms/cc (old ASTM) is taken into the pulled crystal. During the fabrication of a device, the oxygen taken into the crystal is supersaturated and precipitated by heat treatment, thereby to create micro defects in the crystal. Such defects caused by the precipitation of oxygen can be a gettering site of impurities. Gettering which utilizes the defects caused by oxygen precipitation is called intrinsic gettering (hereinafter referred to as IG) which is widely used as one of clean gettering methods. In of clean gettering methods. In order to fully exhibit the advantageous effect of IG, precise control of the amount of the oxygen precipitation is required. In actuality, however, the amount of oxygen precipitation by heat treatment usually vary according to the thermal history of the crystal in the course of the pulling process.
The behavior of such precipitation of oxygen in a silicon wafer is described, for example, in ASTM Task Force Committee Report "Testing for Oxygen Precipitation in Silicon Wafers", Solid State Technology/March 1987, p. 85.
This report shows the conditions of heat treatment for silicon wafers having various initial interstitial oxygen concentrations (hereafter referred to as initial Oi) such as 1,050.degree. C. for 16 hours, or 750.degree. C. for 4 hours and then 1,050.degree. C. for 16 hours (see Table 1 for the conditions). In the report, heat treatment was performed in accordance with the heat treatment conditions of Table 1, and the difference of interstitial oxygen concentrations (hereinafter referred to as delta Oi) before the heat treatment (initial Oi) and after the heat treatment was measured. The result of the measurement is shown in FIGS. 6 and 7.


TABLE 1 ______________________________________ 1 1,050.degree. C. for 16 hrs 2 750.degree. C. for 4 hrs + 1,050.degree. C. for 16 hrs 3 800.degree. C. for 4 hrs + 1,000.degree. C. for 16 hrs 4 900.degree. C. for 4 hrs + 1,000.degree. C. for 16 hrs 5 1,000.degree. C. for 16 hrs ______________________________________
The heat treatment shown in Table 1 has been conventionally used as simple heat treatment conditions (hereinafter referred to as simulation heat treatment) for examining the amount of oxygen precipitation. FIG. 8 shows the yield of devices with respect to delta Oi as a result the simulation heat treatment. To ensure that the delta Oi falls within a hatched portion of FIG. 8, that is, in a range where the yield of device is not adversely effected, a plurality of wafers having substantially the same initial Oi is subjected to IG heat treatment at 650.degree. C. for 60 minutes as is performed conventionally. However, the delta Oi varies from wafer to wafer, and cannot always fall within the range. In the average, the delta Oi draws a S-curve with respect to the initial Oi, but the variance is large.
It is therefore an object of the present invention to reduce variance of the delta Oi in the device manufacturing process into a desired range of the delta Oi with high controllability so as to improve the yield of the devices.


DISCLOSURE OF THE INVENTION

A part of oxygen taken into a crystal by the pulling method becomes donors in the crystal according to the thermal history during the pulling operation. This is called thermal donors. The results of various experiments exhibit t

REFERENCES:
patent: 4140570 (1979-02-01), Voltmer et al.
patent: 4193783 (1980-03-01), Matsushita
patent: 4220483 (1980-09-01), Cazcarra
patent: 4376657 (1983-03-01), Nagasawa et al.
patent: 4622082 (1986-11-01), Dyson et al.
patent: 5066599 (1991-11-01), Kaneta et al.
patent: 5096839 (1992-03-01), Amai et al.
R. Swaroop et al, Testing for Oxygen Precipitation in Silicon Wafers', Solid State Technology, vol. 3, Mar. 1987, pp. 85-89.

Affiliated with

Also associated with

Rating

Semiconductor wafer heat treatment method does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Semiconductor wafer heat treatment method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor wafer heat treatment method will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1097350