Patent ID: 9003832
Filing Date: 2015-04-14
Classification: C03B,Y10T

Abstract:
1. A method of making a silica glass crucible of the type having a substantially bubble-free inner layer, at least some of which dissolves when semiconductor materials are melted in the completed crucible, the method comprising: forming a silica grain layer having an innermost silica grain layer generally in the shape of a crucible having an upwardly directed opening in a cavity of a mold having ports operable to draw gas through the grain; positioning a cover over the opening; introducing a gas into the opening beneath the cover; displacing ambient atmosphere beneath the cover with the introduced gas; thereafter sintering the innermost silica grain layer prior to initiating evacuation of the introduced gas through the ports by applying electric power to a set of electrodes; thereafter initiating evacuation of the introduced gas through the ports; thereafter initiating fusing of the sintered grain and silica grain beneath the sintered grain to form the bubble-free inner layer; evacuating amounts of gas at a first rate from the opening after initiating sintering the innermost silica grain layer; and evacuating substantially more gas from the opening starting more than approximately 25 seconds after initiating sintering the innermost silica grain layer and after electric power exceeds a first level.