JPS62123098A - Silicon single crystal - Google Patents

Abstract

PURPOSE:To obtain a silicon single crystal having great effect on reduction of crystal defect density, by heat-treating the silicon single crystal for semiconductor within a specific temperature range in an atmosphere of H2 gas over a specified time. CONSTITUTION:A silicon single crystal for semiconductors, particularly CZ- silicon single crystal for semiconductors is heat-treated within 800-1,350 deg.C temperature range in an atmosphere of H2 gas for 1sec-48hr. The H2 gas may be 100% H2 gas and diluted with N2 gas or inert gas or a mixed gas thereof. In the latter case, the ratio of H2 to N2 or inert gas is preferably 1:>=9.

Description

DETAILED DESCRIPTION OF THE INVENTION - No. 1 This invention relates to improvements in silicon single crystals for semiconductors.

1 and 1 - Various treatments are carried out to reduce crystal defects in silicon single crystals for semiconductors. For example, one of the technologies to reduce such crystal defects is defect-free NJ.
(Denudedzone> processing is known.

Since the wafer subjected to the defect-free layer treatment is manufactured through a high-temperature heat treatment process, the concentration of M element between the lattices on the wafer surface is reduced. Therefore, micro defects (
Blllk Micro Defects (oxygen precipitates) are not generated, and in the device process, contaminating heavy metal elements that cause crystal defects are caused by micro defects (oxygen precipitates) in the bulk.
3ulk M 1cro defect). That is, an intrinsic gettering effect (rG effect) occurs. As a result, oxidation induced stacking faults
The occurrence of stacking faults is reduced.

It is generally said that the IG effect is useful for improving manufacturing yield and device reliability.

IJ that B tries to turn on.

Even if the wafer is treated with a defect-free layer, if the original oxidation-induced stacking fault density of the substrate is large, the desired oxidation-induced stacking fault density of 8! In some cases, a reduction in the i-layer defect density cannot be expected.

Furthermore, in order to perform the defect-free layer treatment, a considerably long heat treatment time is required, which has the disadvantage that the manufacturing rate becomes low.

Furthermore, in wafers treated with a defect-free layer, oxygen is precipitated between lattices in the crystal, which reduces the mechanical strength of the wafer and makes slipping and the like less likely.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art as described above and to provide a silicon single crystal that is highly effective in reducing crystal defect density.

In order to achieve such an object, the present invention provides a silicon single crystal for semiconductors which is heated in a temperature range of 800° C. to 1350° C. for 1 second to 48 hours in an atmosphere of N2 gas. The gist is a silicon single crystal that is characterized by being heat-treated over a period of time.

Step 1: In this invention, a silicon single crystal is heat-treated in an N2 gas atmosphere. At that time, the processing temperature range is 8
00°C to 1350°C, and the opening time during processing is 1 second to 48°C.
Within hours. N2 gas is H2 gas 100
%, or diluted with N2 gas, inert gas, or a mixed gas thereof.

In the latter case, it is desirable that the ratio of 2 and N2 or inert gas be 1=9 or more.

Note that this invention includes a silicon single crystal grown by the Czochralski pulling method (CZ method) for semiconductors.

1 dish silicone! By heat-treating the No. 11 crystal at high temperature in an N2 gas atmosphere, the crystal defect density induced by the heat treatment can be significantly reduced. Moreover, such heat treatment does not affect other properties and has great practical effects.

N-type cut from the same area of the same CZ-silicon single crystal ingot as above in circle 11, with surface orientation (100
) as shown in Table 1, N2100
Heat treatment was performed in an atmosphere of % gas or )-12100% gas while changing the heat treatment temperature and heat treatment time.

Further, these wafers were heat treated at 1000° C. for 16 hours in a dry O2 gas atmosphere, and then light etched. Table 2 shows the composition of the light etching solution used.

The oxidation-induced stacking fault density of the light-etched samples was measured using a microscope. The results are shown in FIGS. 1 and 2. FIG. 1 shows the occurrence of oxidation-induced stacking faults when the heat treatment time was 30 minutes and the heat treatment temperature was varied from 800°C to 1350'C.

FIG. 2 does not show the occurrence of oxidation-induced stacking faults when the heat treatment temperature was 1100° C. and the heat treatment time was varied from 0 hours to 100 hours.

From this result, the frequency of oxidation-induced stacking faults is lower when N2 annealing and f-1z annealing are performed than when they are not performed, and furthermore, the frequency of oxidation-induced stacking faults is lower in the H2-annealed sample than in the N2-annealed sample. It is clear that the frequency of occurrence of stacking faults is low. The frequency of occurrence of oxidation-induced stacking faults is lower in the N2-annealed sample than in the N2-annealed sample. The effect of this is confirmed.

This experiment revealed that heat treatment in an H2 gas atmosphere suppresses the occurrence of oxidation-induced stacking faults.

As is clear from FIGS. 1 and 2, the appropriate heat treatment time is within the range of 1 second to 48 hours. Further, the appropriate heat treatment temperature ranges from 800°C to 1350°C.

and 1iL 1] type, two adjacent blocks of silicon single crystals of the (100) orientation pulled by the Czochralski method to a length of about 100 cm were taken out. These blocks had a diameter of 125 mm and a length of 5 cm. One of these two blocks was heated to 1200 ml under an atmosphere of 100% H2 gas.
Heat treatment was performed at ℃ for 48 hours. After processing this block and another block into regular mirror wafers, the same oxidation-induced stacking fault density inspection as in Example 1 described above was performed. As a result, the oxidation-induced stacking fault density of wafers cut from blocks heat-treated in an I-12 gas atmosphere was 10/Cm2 on average. On the other hand, the oxidation-induced stacking fault density of wafers cut from the block that was not heat-treated with the two gases was 80/Cm2 on average.
The effect of suppressing the occurrence of oxidation-induced stacking faults by heat treatment in an f2 atmosphere was confirmed.

n-type cut from the same area of a CZ-silicon single crystal ingot with a surface orientation of about 20Ωam (100
) mirror wafers at Hz 10 as shown in Table 3.
1000℃ or 110℃ in 0% gas atmosphere
Heat treatment was performed at 0°C for 305"1, and the mirror surface of some of the samples was mirror-polished to remove a thickness of 5μ. These wafers were inspected for oxidation-induced stacking fault density in the same manner as in Example 1 above. As a result,
As shown in Table 3, the oxidation-induced stacking fault density is almost the same between the wafer heat-treated in the 1"2 gas atmosphere and the T-wafer heat-treated in the H2 gas atmosphere with 55μ removed. N2 annealing averages 50 pieces/
Cm2, with an average of 30 pieces/Cm2 at 1ioo°C.

On the other hand, the oxidation-induced 4a layer defect density of the 4a layer, which was not heat-treated in a gas atmosphere at Hz, was 300 defects/cm2 on average.

This experiment revealed that the effect of reducing oxidation-induced stacking faults by heat treatment in an H2 gas atmosphere is not lost even if the mirror surface is further removed by polishing by about 5 μm.

Tip Ji N-type cut from the same area of the same 07-silicon single crystal ingot, with a surface orientation (100
) mirror wafers were heated to H2 at the ratios shown in Table 4.
In an atmosphere containing a mixture of gas and △r gas, 100
Heat treatment was performed at 0°C for 30 minutes. These wafers were subjected to the same oxidation-induced stacking fault density inspection as in Example 1 (previously).

The results showed that as the proportion of N2 in the mixed gas decreased, oxidation-induced stacking faults tended to occur more easily, as shown in Figure 3.
In the following cases, the effect of suppressing oxidation-induced stacking faults by this heat treatment is not observed.

As is clear from this experimental result, it is appropriate that the ratio of N2 and N2 or inert gas be 1:'1 or higher.

According to the present invention, the effect of reducing crystal defect density is extremely significant, and effective results can be obtained even with a short treatment time. In particular, in the n-type, which had a poor yield due to the density of oxidation-induced stacking faults, even with a high resistance,
According to the present invention, the average oxidation-induced stacking fault density is about 115
decreased to

Note that the defect-free zone (denuded zone) treatment and the heat treatment using 1"2 gas are completely different treatments, and for example, it is also possible to combine the heat treatment with N2 gas and the defect-free layer treatment. Generally speaking, this defect-free layer treatment is limited to specialized applications and is not normally applied to wafers.

[Brief explanation of drawings]

1 to 3 are graphs showing the effects of the present invention. 7----~, Agent Patent Attorney Toru Tanabe (11,:”:”,)1noF
s, rc Table 1 Table 2 Light etching conc, HF: 6
0m Qconc, HNO3: 30mQ 5M CrO3: 30mQ Cu(NO3)2 ・3f-1z O2! J00nC
, CI-h Coo) → :
60mQ+-120
: 60mQ table 3 table 4

Claims (4)

[Claims] (1) Semiconductor silicon single crystal at 800°C to 1350°C in an H_2 gas atmosphere
A silicon single crystal characterized by being heat-treated at a temperature ranging from 1 second to 48 hours. (2) The silicon single crystal according to claim 1, wherein the H_2 gas is 100% H_2 gas. (3) The silicon single crystal according to claim 1, wherein the H_2 gas is diluted with N_2 gas, an inert gas, or a mixed gas thereof. (4) The silicon single crystal according to claim 1, which is a CZ-silicon single crystal for semiconductor use.