The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 18, 1982
Filed:
Mar. 04, 1981
Werner Zulehner, Emmerting, DE;
Abstract
In the crucible pulling of silicon according to the Czochralski technique, ilicon monoxide forms as a result of the silicon melt reacting with the quartz crucible containing the melt, and evaporates and deposits in the form of solid particles on the upper edge of the crucible, on the monocrystalline rod, on the walls of the vessel, and also on recharging devices in the upper pulling chamber. These solid particles can fall back into the melt and then cause dislocations and polycrystalline growth in the growing silicon rod. As a result of the reaction of the carbon of the hot graphite parts with silicon monoxide, carbon monoxide is also formed and this partially diffuses into the melt and gives rise to carbon impurities in the silicon rod. In addition, because of heat irradiation from the inner wall of the quartz crucible as it becomes more empty, high pulling speeds, such as those usual in crucible-free zone pulling, cannot be obtained. These disadvantages of the conventional crucible-pulling process are effectively obviated according to the invention by a pot-like device which entails a partial covering of the melt surface, the crucible and the space laterally adjoining the crucible.