JPH0459688A - Double crucible for growing single crystal - Google Patents

Abstract

PURPOSE:To prevent the transition of a single crystal into a polycrystal and improve the yield of the Si single crystal by disposing a coating member having a higher thermal conductivity than quartz on the inner surface deposited above the surface of a melted material in an inside crucible in the quartz double crucible for growing the Si single crystal by Czochralski method. CONSTITUTION:A quartz double crucible consisting of an inside crucible 2 and an outside crucible 9, penetrated holes 11 being formed between both the crucibles 2 and 9, is disposed in a chamber 12 of a Si single crystal-growing device 1, and a coating member (e.g. a coating member made of Mo) having a higher thermal conductivity than that of quartz is disposed on the inner surface of the inner crucible 2 deposited above the melted material 5. By Czochralski method a material 10 is fed and a Si single crystal 6 is simultaneously continuously lifted from the melted material 5 in the inner crucible 2, thereby permitting to reduce a phenomenon where SiO gas generated from the surface of the melted material 5 is deposited on the exposed inner surface of the inner crucible 2, further to inhibit the dropping of the deposit into the melted material 5 and the generation of polycrystals in the single crystal 6, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a quartz double crucible for growing Si single crystals by the Czochralski method. [Prior Art] Single crystals are generally grown by the Czochralski method, and as a method for obtaining long single crystals, there is a continuous pulling method in which raw materials are continuously supplied during the growth of the single crystal. When the raw material supplied in the continuous pulling method adheres to the growing single crystal, the single crystal becomes polycrystalline and Si
Single crystal yield decreases.

In order to prevent the raw materials from adhering to the single crystal during growth, a double crucible, the vertical cross-sectional view of which is shown in FIG. 3697
It is disclosed in Publication No. 7.

In the figure, l is a single crystal growth device, 2 is an inner crucible, and 4
5 is a heater, 5 is a melt, 6 is a single crystal, 7 is a susceptor, 8 is a crucible support rod, and 9 is an outer crucible.

lO is the feed material, 11 is the through hole, 12 is the chamber, 13
is a raw material supply device.

The material of the double crucible is quartz, and since quartz has low thermal conductivity, the portion of the inner crucible 2 exposed from the melt 5 has a low temperature.

On the other hand, the Si melt reacts with the quartz crucible and S
iO gas is generated, the SiO gas adheres to the low temperature part of the inner crucible 2, and the SiO gas adheres to the inner surface of the inner crucible 2.
There is a problem in that the particles fall on the surface of the melt 5 and adhere to the growing single crystal 6, turning it into polycrystals, reducing the yield of single crystals.

[Problem to be Solved by the Invention 1] The present invention attempts to solve the problems of the above-mentioned prior art by preventing cooling of the inner surface exposed from the melt in the inner crucible.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a quartz double crucible used for growing Si single crystals by the Czochralski method, in which the double crucible has a molten liquid in an inner crucible. The present invention provides a double crucible for growing a single crystal, characterized in that the more exposed inner surface is provided with a coating material having higher thermal conductivity than quartz.

[Effect]

The present invention will be explained using FIG. 1, which shows a longitudinal cross-sectional view of an embodiment.

In the figure, numeral 3 denotes a coating material provided on the inner surface exposed from the melt in the inner crucible, and other symbols are the same as in FIG. 2.

As the covering material 3, Mo, W, etc., which have higher thermal conductivity than quartz, are preferably used.

The inner surface of the inner crucible 2 exposed from the melt 5 is coated with a coating material having high thermal conductivity, so the temperature decreases less, and therefore the above-mentioned adhesion of SiO scum is reduced. It is possible to reduce the decrease in yield due to the falling of aggregates into the melt 5 and the polycrystallization of the single crystal 6.

[Example] An apparatus of the type shown in FIG. 1 was used. The inner diameter of the inner crucible is 300 mm, the inner diameter of the outer crucible is 400 mm, MO with a thickness of 1 mm is used as a covering material, and the amount of fused fi is kept constant during the growth of the single crystal. This book was raised.

As a comparative example, a single crystal was grown using the same apparatus as that used in the example except that an apparatus lacking a coating material was used.

Table 1 shows the distance from the top of the single crystal and the number of polycrystallized positions in Examples and Comparative Examples6. In Comparative Examples, all grown single crystals polycrystallized within 600 mm, While more than half of the cases were polycrystalline within 400 mm, in the examples.

Five of the 20 sea urchins grown did not polycrystallize at all, and even if they did polycrystallize, the position shifted to the lower end compared to the comparative example, and the present invention significantly improved the yield of Si single crystals.

[Effects of the Invention] By using the crucible of the present invention, the yield of Si single crystals could be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a single crystal growth apparatus using a double crucible according to the present invention, and FIG. 2 is a longitudinal sectional view of a conventional single crystal growth apparatus using a double crucible. l・-・Single crystal growth device 2-・Inside...1 Crucible 3
-...Coating material 4-Heater 5...Melt 6...Single crystal 7...Susceptor
8--Crucible support rod 9--Outer crucible
10...-Feed material 11...-Through hole 12.
-Chamber 13--Raw material supply device

Claims (1)

[Claims] 1. In a quartz double crucible used for growing Si single crystals by the Czochralski method, the double crucible is provided with a coating material having higher thermal conductivity than quartz on the inner surface exposed from the melt of the inner crucible. For single crystal growth 2 characterized by
A heavy crucible.