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:
Jul. 11, 1995
Filed:
Jan. 12, 1993
Singh P Kumar, New Delhi, IN;
Prem Prakash, New Delhi, IN;
Council of Scientific & Industrial Research, New Delhi, IN;
Abstract
This invention relates to a process for the preparation of polycrystalline silicon ingots by providing a first layer of coating on the inside walls of a mold with a slurry of silicon nitride powder in an organic binder dissolved in a solvent; charging the said coated mold with silicon pieces along with calcium chloride or/and calcium fluoride; heating the mold to a temperature in the range of 1420.degree.-1500.degree. C. so as to melt the silicon, by keeping the mold inside the furnace; bringing down the temperature of the mold to a temperature 5.degree.-10.degree. C. above the melting point of silicon; withdrawing the mold containing the melt downwardly and slowly from the hot zone of the furnace so that the solidification of the melt starts from the bottom of the mold and proceeds towards the top as the withdrawal continues till all the melt solidifies; cooling the mold to the room temperature under inert atmosphere and removing the polycrystalline silicon ingot from the mold.