JPH05221773A - Method and device for producing silicon single crystal - Google Patents

Abstract

PURPOSE:To control the oxygen depositing behavior in a silicon single crystal and to prevent the generation of crystal defects (OSF, etc.) at the time of producing a silicon single crystal by the Czochralski method. CONSTITUTION:A silicon single crystal is produced by a device for pulling up a silicon single crystal. In this case, the silicon single crystal pulled up from the melt is cooled from 600 to 350 deg.C at the rate of 1.5 to 200 deg.C/min. A cooler 10 is provided in the pull chamber 9 of the device to control the cooling rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents generation of oxygen-induced stacking faults (OSF) in a silicon single crystal and oxygen precipitation in the production of a large-diameter silicon single crystal by the Czochralski method (CZ method). The present invention relates to a method for producing a silicon single crystal and a device therefor for controlling the amount.

[0002]

2. Description of the Related Art As a method for producing a single crystal, a CZ method has been widely used in which a crystal is pulled from a melt in a crucible while growing the crystal. In this CZ method, the oxygen precipitation concentration changes depending on the heat history of the ingot during crystal growth. This amount of precipitation determines the size of the warp of the Si wafer, and
The ic gettering (IG) effect was determined. Oxygen precipitates called oxygen donors are formed in the Si wafer by the low temperature heat treatment at 350 to 650 ° C. This oxygen donor determines the amount of oxygen precipitation during high temperature heat treatment of the wafer. In the conventional method, as disclosed in Japanese Patent Publication No. 58-120591 and Japanese Patent Application Laid-Open No. 1-82841, the amount of oxygen precipitation is controlled by low temperature heat treatment at 450 ° C. to 650 ° C. after processing into a Si wafer. .. However, as the diameter of the silicon crystal is increased to 8 inches and 12 inches (hereinafter simply referred to as 8 and 12 inches), the conventional 5
It has a different thermal history than the 6-inch crystal.

When the thermal history of the ingot was measured using a thermocouple as shown in FIG. 1, the cooling rate of silicon single crystals of 8 and 12 inches was gradually cooled below 600 ° C. as compared with 6 inches. It turned out that Further, as shown in FIG. 4, the cooling rate of 600 ° C. or lower is 8: 1 for 6 inches.
It is faster than 2 inches. The crystal quality of the silicon single crystal in such a state was evaluated. In addition, as shown in FIG. 2, the oxygen precipitation amount of the crystals of 8 and 12 inches was significantly increased as compared with the case of 6 inches. The oxygen precipitation was determined by performing a heat treatment in nitrogen at 800 ° C. for 4 hours and further measuring the oxygen concentration by FTIR measurement before and after the heat treatment at 1000 ° C. for 16 hours in dry oxygen gas.

Further, in the CZ method, the generation of OSF also changes due to the ingot cooling in the temperature range described above. It is considered that in the low temperature region of 650 ° C. or lower, oxygen and metal impurities are precipitated, and the OSF generation nucleus grows largely. Therefore, the OSF changes depending on the cooling rate. The result is shown in FIG.
The OSF density of the 12 inch crystal increased more than that of the 6 inch. The OSF is measured by observing with a microscope after heating a silicon single crystal in wet oxygen gas at 1100 ° C. for 80 minutes and then performing a light etching of 1.5 μm. The conventional cooling in the furnace is cooling with argon gas in a water-cooled stainless steel chamber. There was no other way to control the cooling rate than increasing the pressure in the furnace and the flow rate of argon.

[0005]

SUMMARY OF THE INVENTION The present invention controls the amount of oxygen precipitation in a silicon single crystal in the production of a silicon single crystal by the Czochralski method (CZ method), and the OS
The purpose is to prevent the generation of F.

[0006]

A method and an apparatus for pulling a silicon single crystal of the present invention is an apparatus for pulling a silicon single crystal from a melt in a crucible, and a cooling rate of the silicon single crystal pulled from the melt. In order to adjust the temperature, a coolant is sprayed on the silicon single crystal to cool the temperature range of 600 ° C. to 350 ° C. at a cooling rate of 1.5 ° C./min or more and 200 ° C./min or less. ..

Next, the apparatus of the present invention will be described in detail with reference to the drawings of the embodiments. FIG. 6 is a diagram showing a configuration of an embodiment of a silicon single crystal pulling apparatus of the present invention and a situation at the time of pulling an ingot, and FIG. 7 similarly shows a silicon single crystal pulling apparatus of the present invention and a rapid cooling of the ingot. It is a figure showing a situation. Further, FIG. 8 is a cross-sectional view taken along the line AA of the quenching device of FIG. 7. In the silicon single crystal pulling apparatus of this embodiment, the silicon single crystal 4 is melted from the melt 3 in the quartz crucible 1.
Is raised. In FIG. 6, the melt 3 is heated by a tubular heater 5 and covered with a tubular outer shield 6. The grown silicon single crystal 4 moves to the pull chamber 9. Thereafter, the gate valve 11 separates the pulling furnace chamber 8 and the pull chamber 9. As shown in FIG. 7, the silicon single crystal 4 is subjected to a quenching heat treatment in a quenching device 10 in a pull chamber 9. Argon gas, helium, nitrogen gas, nitrogen, dry air, gas-liquid mist (water and air), water, or the like can be used as the cooling refrigerant.
The quenching device 10 can irradiate the silicon single crystal 4 with these refrigerants. The quenching device 10 can control the cooling rate of the silicon single crystal ingot by spraying the cooling medium. Further, a detailed view of the cooling part of the quenching device is shown in FIG. Further, the quenching device 10 does not need to be mounted inside the pull chamber 9 and can be installed outside the pulling furnace. The appropriate cooling rate condition for the silicon single crystal ingot is determined from the following. As shown in FIG. 5, the temperature of the silicon single crystal is 600 to 350 ° C.
If the cooling rate during this period is 1.5 ° C./minute or less, a large amount of OSF may be generated on the Si wafer, and a large amount of oxygen in the wafer may be precipitated during the high temperature heat treatment. On the other hand, when the cooling rate is 100 ° C./min or more, the silicon single crystal 4 is cracked. Therefore, the temperature of the silicon single crystal is 600-35.
The cooling rate between 0 ° C was set to 1.5 ° C / min or more and 200 ° C / min or less.

[0008]

In the apparatus for pulling a silicon single crystal according to the present invention, a coolant is blown onto the pulled silicon single crystal to obtain a temperature of 600.degree.
It is possible to cool the temperature range of 350 ° C. at a cooling rate of 1.5 ° C./min or more and 200 ° C./min or less. Therefore, oxygen donors and nuclei of OSFs generated in the crystal can be reduced. With this apparatus, the amount of oxygen precipitated in a large-diameter silicon single crystal can be controlled to be constant, and further, the occurrence of oxidation-induced stacking fault (OSF) in the silicon single crystal can be prevented.

[0009]

EXAMPLES Examples of the present invention will be specifically described based on Tables 1 and 2 of Examples. In the apparatus shown in FIGS. 6 and 7, an inner diameter 18 reinforced with a graphite crucible 2 from the outside
Into an inch quartz crucible 1a, 40 kg of 6 inch, 60 kg of 8 inch, and 100 kg of 12 inch of polycrystalline silicon were charged and melted as a raw material. The pulling speed of the silicon single crystal 4 is 1.0 mm / m.
pulled up in. The straight body length of the silicon single crystal 4 is 6
It was 600 mm in inches, 500 mm in 8 inches, and 400 mm in 12 inches. The pulled silicon single crystal 4 was moved to the pull chamber 9 and cooled by the rapid cooling device 10. Argon, helium, nitrogen, dry air, gas-liquid mist (water and air), and water were used as the refrigerant. The cooling nozzle has a slit shape of 2 × 20 mm ² and a space of 30 mm, 1
I made two. In this case, the cooling conditions of the 8- and 12-inch silicon single crystals 4 at 600 ° C. or lower were controlled to be the same as the 6-inch cooling conditions. No difference was detected between the oxygen precipitation amount and the OSF density of 6 inches in these 8 and 12 inch silicon single crystals. The oxygen precipitation was determined by measuring the oxygen concentration by FTIR measurement before and after heat treatment in nitrogen at 800 ° C. for 4 hours and further in dry oxygen gas at 1000 ° C. for 16 hours. O
SF is a silicon single crystal in wet oxygen gas at 1100 ° C.
After heating for 80 minutes, light etching was performed to obtain a thickness of 1.5 μm, which was then measured by microscopic observation. Further, when liquefied nitrogen was used as the refrigerant, or when the cooling rate was higher than 200 ° C./min by increasing the amount of water in gas-liquid mist (water and air), cracks were generated in the ingot.

[0010]

2. Description of the Related Art As in the case of the present invention, in the apparatus shown in FIGS. 6 and 7, a silicon single crystal 4 was placed in a quartz crucible 1a having an inner diameter of 18 inches and reinforced with a graphite crucible 2 from the outside and 6 inches as a raw material. 40 kg, 60 for 8 inches
In the case of kg and 12 inches, 100 kg of polycrystalline silicon was charged and melted. The silicon single crystal 4 was pulled at a pulling rate of 1.0 mm / min. The pulled silicon single crystal 4 was moved to the pull chamber 9 and subjected to cooling heat treatment in the pull chamber 9. The inside of the pull chamber 9 was decompressed in an argon atmosphere with an argon flow rate of 10 l / min and a furnace pressure of 10 mbar. In this case, as shown in FIGS. 1 and 2, the cooling rate of the silicon single crystal of 8 to 12 inches was gradually cooled at 500 ° C. or less as compared with 6 inches. The crystal quality of the silicon single crystal in such a state was evaluated. As shown in FIG. 2, the oxygen precipitation amount of the crystals of 8 and 12 inches was significantly increased as compared with the case of 6 inches. The oxygen precipitation was determined by measuring the oxygen concentration by FTIR measurement before and after heat treatment in nitrogen at 800 ° C. for 4 hours and in dry oxygen gas at 1000 ° C. for 16 hours. Further, as shown in FIG. 3, the OSF densities of the 8 and 12 inch crystals increased more than those of the 6 inch case. The OSF is measured by microscopic observation after heating a silicon single crystal in wet oxygen gas at 1100 ° C. for 80 minutes and then performing a light etching of 1.5 μm.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

According to the present invention, the Czochralski method (C
In the production of a silicon single crystal by the Z method), the oxygen precipitation amount of the large diameter silicon single crystal can be controlled to be constant, and further,
Oxidation-induced stacking fault (OSF) generation in a silicon single crystal is prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing a thermal history of a crystal of 6, 8 or 12 inches below 600 ° C.

FIG. 2 is a diagram showing oxygen precipitation behavior of 6, 8 and 12 inch crystals.

FIG. 3 is a diagram showing OSF generation behavior of 6, 8 and 12 inch crystals.

FIG. 4 is a diagram showing cooling rates of 600 ° C. or lower for 6, 8 and 12 inch crystals.

FIG. 5 is a diagram showing a relationship between cooling rate and OSF generation.

FIG. 6 is a device diagram showing an embodiment of the present invention.

FIG. 7 is a device diagram showing the same embodiment of the present invention.

8 is a cross-sectional view taken along the line AA of the cooling device of FIG.

[Explanation of symbols]

 1 Quartz Crucible 2 Graphite Crucible 3 Melt 4 Silicon Single Crystal 5 Heater 6 Outer Shield 7 Support Stand 8 Pulling Furnace Chamber 9 Pull Chamber 10 Quenching Device 11 Gate Valve 12 Slit

Front page continued (72) Masamichi Okubo 3434 Shimada, Hitsu-shi, Yamaguchi Prefecture, Nittatsu Electric Co., Ltd., Hikari Plant (72) Inventor Kiyoshi Kojima, 3434 Shimada, Hikari-shi, Yamaguchi Prefecture, Nittetsu Electric Co., Ltd., Hikari Plant (72) Inventor ▲ ha ▼ Ryuichi Iku 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Nippon Steel Corporation Advanced Technology Research Laboratories

Claims (3)

[Claims] 1. When manufacturing a silicon single crystal with a silicon single crystal pulling apparatus, the cooling rate of the silicon single crystal pulled from the melt in the temperature range of 600 to 350 ° C. is 1.5 ° C.
/ Min or more and 200 ° C / min or less, The manufacturing method of the silicon single crystal characterized by the above-mentioned. 2. When manufacturing a silicon single crystal with a silicon single crystal pulling apparatus, the temperature range up to 600 ° C. of the silicon single crystal obtained by pulling silicon from a melt is cooled in the silicon single crystal pulling apparatus, A temperature range of 600 ° C. to 350 ° C. is taken out from the silicon single crystal pulling apparatus and cooled at a cooling rate of 1.5 ° C./min or more and 200 ° C./min or less. 3. An apparatus for producing a silicon single crystal, wherein a pulling apparatus for the silicon single crystal is provided with a cooling device for adjusting a cooling rate of the silicon single crystal in the pull chamber.