Heraeus Shin-Etsu America, Inc.

Heraeus Quarzglas Gmbh & Co Kg

Shin-Etsu Quartz Products Co., Ltd.

Robert Joseph Coolich

Katsuhiko Kemmochi

Walter Lehmann

Thomas Kayser

Michael Randall Fallows

A silica crucible is made in a mold cavity of the type in which ambient atmosphere can be drawn through silica grain in the cavity. In one embodiment, a silica grain layer is formed in the mold cavity and gas, which may comprise helium, nitrogen, hydrogen, or a mixture thereof, is introduced into the mold cavity. The silica grain layer is heated while substantially no ambient atmosphere is drawn through the silica grain. Thereafter, at least a portion of the silica grain layer is fused while drawing ambient atmosphere through the silica grain. The gas displaces air in the mold cavity thereby reducing nitrogen oxides and ozone.

Method of making a silica crucible in a controlled atmosphere

During a CZ or similar process, a silica crucible is held in a graphite or similar susceptor while being heated to above between about 1580 and 1620 degrees C. Vents or grooves formed in at least one of the outer surface of the crucible and the inner surface of the susceptor permit gasses to vent upwardly and out from between the crucible and susceptor. This permits gas evolved from the crucible as a result of the heat to be vented rather than expanding between the crucible and susceptor thereby deforming the crucible.

Method and apparatus for venting gas between a crucible and a susceptor

A method of making a silica crucible in a mold cavity of the type in which air is drawing through silica grain placed in the mold cavity. A pure silica grain layer is formed on top of a natural silica grain layer. At least a portion of the purse silica grain layer is fused while substantially no air is drawn through the silica grain. Any remaining pure silica grain and a least a portion of the natural silica grain layer is fused while drawing a substantially higher volume of air through the silica. At least a portion of the fused pure silica grain layer is then sublimated.

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North Bonneville, WA, United States of America

Robert Joseph Coolich