Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Including specific material of construction
Patent
1991-06-14
1992-08-18
Kunemund, Robert
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Including specific material of construction
1566171, 1566181, 1566204, 156DIG64, 422248, B01D 900
Patent
active
051397501
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus for manufacturing large-diameter silicon single crystals in accordance with the Czochralski method.
BACKGROUND ART
In the field of LSIs, the diameter required for silicon single crystals has been increased year after year. At present, silicon single crystals of 6 inches in diameter are used for the latest devices. It is said that in the future silicon single crystals of 10 inches or more in diameter, e.g., silicon single crystals of 12 inches in diameter will be needed.
The silicon single crystal manufacturing methods according to the Czochralski method are classified into two types of conceptions. One type is a method in which a crucible is rotated and the other type is a method in which a crucible is not rotated. At present, all the silicon single crystals according to the CZ method, which are used for LSIs, are manufactured by the method of rotating a crucible and a silicon single crystal in the opposite directions and heating the crucible by an electric resistance heater surrounding the side of the crucible. In spite of many attempts silicon single crystals of over 5 inches in diameter have not been manufactured up to date by any methods in which the crucible is not rotated or by any other heating methods than the above-mentioned one. Nor they will be produced in the future. The reason is that it is impossible to obtain a temperature distribution which is completely concentric with a growing silicon single crystal without the rotation of the crucible and by such heating methods as magnetic induction heating or electric resistance heating from the bottom surface of the crucible. The growth of a silicon single crystal is extremely sensitive to the temperature distribution.
In accordance with the CZ method which rotates the crucible (hereinafter referred to as the ordinary CZ method), a strong convection is caused in the molten silicon owing to the crucible rotation and the electric resistance heater attached to the side of the crucible, and the molten silicon is stired excellently. This is desirable for the growth of a large-diameter silicon single crystal. 1n other words, a complete and uniform concentric temperature distribution of the molten silicon surface is obtained for the silicon single crystal. Therefore, the present invention is based on the ordinary CZ method. As mentioned previously, there is a great difference in molten silicon flow between the ordinary CZ method and the other CZ method. This difference results in considerable variations in the growth of silicon single crystals. As a result, there are great differences between the two with respect to the functions of the furnace components (e.g. the heater). The two methods differ entirely with respect to the conception for the growth of a silicon single crystal.
In accordance with the ordinary CZ method, the amount of molten silicon within the crucible is decreased as a silicon single crystal grows. Thus, as the silicon single crystal grows, the dopant concentration is increased and the oxygen concentration is decreased in the silicon single crystal. In other words, the properties, e.g., the electric resistivity of the silicon single crystal varies in the direction of its growth. Since the quality required for LSIs has been made severer year after year with increase in the level of integration of LSIs, this problem must be overcome.
As a means of solving this problem, there is known a method in which the interior of a quartz crucible according to the ordinary CZ methods is divided by a cylindrical quartz partition member including holes formed therethrough for molten silicon and a cylindrical silicon single crystal is grown on the inner side of the partition member while feeding granular silicon starting material to the outer side of the partition member (e.g., Patent Publication No. 40-10184, page 1, lines 20 to 35).
As pointed out in Laid-Open Patent No. 62-241889 (page 2, lines 12 to 16), this method is disadvantageous in that solidification of the molten silicon tends to
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Araki Kenji
Kamio Hiroshi
Shima Yoshinobu
Suzuki Makoto
Garrett Felisa
Kunemund Robert
Meller Michael N.
NKK Corporation
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