Corning Incorporated

Nicholas LeBlond

Daniel Warren Hawtof

Jeffrey Todd Kohli

Christopher Scott Thomas

Alexandre Michel Mayolet

Paul Maynard Schermerhorn

Pawan Saxena

Michelle M L Fredholm

Viktoria Pshenitsyna

The invention is directed to a method for growing metal fluoride crystals suitable for use in below 200 nm optical lithography systems, the method comprising including at least the step of heating a crystal growth furnace to a temperature in the range of 1400-2000&#xb0; C. to purify the furnace by removal of sulfur and chlorine prior to using the furnace for growing metal fluoride single crystals.

Furnace purification and metal fluoride crystal grown in a purified furnace

An apparatus for making a crystal pre-melt includes a hermetically-sealed muffle furnace made of a non-porous refractory material, at least one port for entry and exit of gaseous substance within the muffle furnace, a temperature-controlled zone defined inside the muffle furnace, and a crucible for holding crystal raw material in solid or molten form inside the muffle furnace. The crystal pre-melt is made by disposing crystal raw material in loose powder, pressed powder, granular, or densified form in the temperature-controlled zone, heating the temperature-controlled zone to a treatment temperature that enables reaction between a fluorinating agent and oxides in the crystal raw material, reacting the fluorinating agent with the crystal raw material to produce volatile gases, removing the volatile gases from the muffle furnace, heating the crystal raw material to form a melt, and solidifying the melt to form the crystal pre-melt.

Method and apparatus for making a crystal pre-melt

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Painted Post, NY, United States of America

Nicholas LeBlond