Jon M Schalla

US Patent:

52981070, Mar 29, 1994

Filed:

Feb 27, 1992

Appl. No.:

7/843987

Inventors:

Lance A. Scudder - Mountain View CA
Norma Riley - Pleasanton CA
Jon M. Schalla - San Jose CA

Assignee:

Applied Materials, Inc. - Santa Clara CA

International Classification:

C30B 2512

US Classification:

156610

Abstract:

A technique for impeding the formation of mechanical bonds between workpieces, such as semiconductor wafers, and a carrier or susceptor on which they are supported during a deposition or layer formation process, such as in epitaxial processing. In the formation of relatively thick films, greater than approximately 50 microns (50. mu. m) thick, wafers can become mechanically bonded to the susceptor on which they are supported, and are subject to damage caused by thermal stresses during a cooldown phase of processing. In the disclosed method, the speed or direction of rotation of a rotatable susceptor is abruptly changed at least once, or periodically during processing. Slight movement of the wafers with respect to the susceptor during each rotation speed change or reversal tends to break any bonds before they can develop strength, and production yields of acceptable wafers are significantly improved.