Single-crystal – oriented-crystal – and epitaxy growth processes; – Processes of growth from liquid or supercritical state – Having pulling during growth
Reexamination Certificate
1999-03-22
2001-08-21
Hiteshew, Felisa (Department: 1765)
Single-crystal, oriented-crystal, and epitaxy growth processes;
Processes of growth from liquid or supercritical state
Having pulling during growth
Reexamination Certificate
active
06277192
ABSTRACT:
INTRODUCTION AND BACKGROUND
The present invention relates to a crystal pulling unit for the production of a crystal block, which includes a crucible for the meltable material forming the crystal block and which further includes a recharging tube leading to the crucible to supply the meltable material in granulate form.
Crystal pulling units that are generally of the aforementioned type are known for the pulling of crystal blocks from semiconductor material using the Czochralski method. These units mostly work continuously in that during the pulling of the crystal block, the meltable material which ultimately forms the melt is constantly supplied in the form of a granulate. Reference is made to German Patent No. 2,821,481 as an example of the state of the art which is incorporated herein by reference. Comparable crystal pulling units are, however, also used for semi-continuous Czochralski pulling methods. The recharging tube is made of quartz material, as is the crucible.
While operating such crystal pulling units, one often finds that clogging occurs in the recharging tube. If that happens, the unit must be brought to a standstill, causing interruption of the process which generates relatively higher costs. Another disadvantage of known crystal pulling units lies in the fact that when finer granulate fractions impact on the liquid level of the melt in the crucible, these fractions “dance” on the liquid level, instead of melting, and in this way enter the pulling space above the melt and contaminate it.
It is therefore an object of the present invention to design a crystal pulling unit of the type discussed above in such a way that the danger of clogging in the recharging tube is as small as possible, and that fine-grain fractions are not able to pass over into the pulling space above the liquid level.
SUMMARY OF THE INVENTION
The above and other objects of the present invention can be achieved by designing the recharging tube to have an annular space between an inner wall and an outer wall. More particularly, it is a feature of the invention that this annular space is open on the lower front of the recharging tube and connects with a protective gas source for the supply of protective gas.
REFERENCES:
patent: 4904143 (1990-02-01), Drechsel et al.
patent: 4968380 (1990-11-01), Freedman et al.
patent: 5229082 (1993-07-01), Seidensticker et al.
patent: 5242531 (1993-09-01), Klingshirn et al.
patent: 5324488 (1994-06-01), Klingshirn et al.
patent: 5580171 (1996-12-01), Lim et al.
patent: 5900055 (1999-05-01), Nagaietal
patent: 4106589 (1992-09-01), None
patent: 0314858 (1989-05-01), None
patent: 0771891 (1997-05-01), None
patent: 2240287 (1991-07-01), None
Patent Abstracts of Japan, No. 07118089 (Komatsu Electron Metals Co. Ltd.), May 9, 1995.
Patent Abstracts of Japan, No. 09227271, (Shin Etsu Handotai Co. Ltd.), Sep. 2, 1997.
Patent Abstracts of Japan, No. 07265684, (Komatsu Electron Metals Co. Ltd.), Oct. 17, 1995.
Patent Abstracts of Japan, No. 07118089, May 9, 1995.
Patent Abstracts of Japan, No. 59008694, Jan. 17, 1984.
Patent Abstracts of Japan, No. 03008791, Jan. 16, 1991.
Altekruger Burkhard
Aufreiter Joachim
Hiteshew Felisa
Leybold Systems GmbH
Smith , Gambrell & Russell, LLP
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