Arthur D. Little, Inc.

Peter C VonThuna

Wilson P Menashi

Joseph F Wenckus

Roger A Castonguay

Martin L Cohen

Apparatus is provided for forming, by the Czochralski technique, single semiconductor crystals having essentially uniform diameters throughout their lengths. The apparatus includes means to monitor and control crystal diameter which takes advantage of the fact that the melt volume from which the crystal is pulled and the dielectric crucible containing the melt volume can be incorporated in a crucible assembly circuit in which the resistance varies with the melt volume level in the crucible. Determination of the difference between the measured resistance in the crucible assembly circuit and a programmed reference resistance produces a signal which is used to control one of two operational parameters--the rate at which the crystal is pulled or the temperature of the melt volume--to produce a uniform-diameter crystal.

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Lexington, MA, United States of America

Peter C VonThuna