Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Including specific material of construction
Patent
1991-12-23
1994-01-18
Chaudhuri, Olik
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Including specific material of construction
1566171, 1566204, 156DIG64, 422245, C30B 1530
Patent
active
052797988
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus for manufacturing large-diameter silicon single crystals according to the Czochralski method. More particularly, the invention relates to a silicon single crystal manufacturing apparatus including a rotation-type quartz crucible containing molten silicon, an electric resistance heater for heating the quartz crucible from the side thereof, a quarts partition member arranged to divide the molten silicon to an inner single crystal growing section and an outer material melting section within the quartz crucible and having small holes for permitting passage of the molten silicon therethrough, and starting material feed means for continuously feeding starting material silicon to the material melting section.
BACKGROUND ART
In the field of LSIs, the required diameter for silicon single crystals has been increased year after year. At present, crystals of 6 inches in diameter are used for the latest devices. It is said that in the future crystals of 10 inches or over in diameter, e.g., crystals of 12 inches in diameter will be needed.
In accordance with the Czochralski method (CZ method) which is known as a method of manufacturing large-diameter silicon single crystals, the amount of molten silicon in a crucible is decreased as a single crystal is grown. As a result, the dopant concentration is increased and the oxygen concentration is decreased in the crystal as the crystal is grown. In other words, the properties of the crystal are varied in the direction of its growth. Since the quality required for silicon single crystals 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, a method has been known from the old in which the interior of a quartz crucible according to the ordinary Czochralski method is divided by a quartz crucible having small holes for molten silicon so that the inner side forms a single crystal growing section and the outer side forms a material melting section thereby growing a cylindrical silicon single crystal on the inner side while continuously feeding starting material silicon to the material melting section, and many patents have been disclosed (Patent Publication No. 40-10184, Laid-Open Patent No. 62-241889, Laid-Open Patent No. 63-233092, Laid-Open Patent No. 63-319287, Laid-Open Patent No. 64-76992 and Laid-Open Patent No. 1-96087).
Where a silicon single crystal is manufactured by use of a double structure crucible incorporating therein a partition member on the basis of the prior art technique such as described above, however, the heat environment in the molten silicon is the very opposite to that in cases in which the ordinary single structure crucible without any partition member is used.
FIGS. 9 and 10 are longitudinal section views respectively showing the cases of the above-mentioned single structure crucible and double structure crucible. In the Figures, numeral 21 designates a crucible, 22 a partition, 4 molten silicon, 5 a pulled silicon single crystal, and 12 small holes formed through the partition 22 for molten silicon. Also, arrows show the directions of the convection of molten silicon. In the case of FIG. 9, the crucible side wall portion is higher in temperature than the crucible bottom portion. In other words, the amount of heat supplied through the crucible side wall portion is greater than the amount of heat supplied through the crucible bottom portion. Reflecting this fact, the convection of the molten silicon within the quartz crucible 21 is predominated by the flows indicated by the arrow in FIG. 9. In the case of FIG. 10, however, the amount of heat supplied to the single crystal growing section through the crucible side is such that the proportion of the heat input through the bottom portion of the crucible 21 is increased as compared with the case of FIG. 9. This is due to the fact that the side portion of the partition 22 is remote from the heat source and the temperature distribution in the m
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Kamio Hiroshi
Keneto Takeshi
Chaudhuri Olik
Garrett Felisa
Meller Michael N.
NKK Corporation
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