SEDL / STP / STP712-EB / STP35134S

Measurement and Retention of Recombination Lifetime

Blais, PD
Supervisor and laboratory technician, Westinghouse Electric Corp. Research and Development Center, Pittsburgh, Pa.

Seiler, CF
Supervisor and laboratory technician, Westinghouse Electric Corp. Research and Development Center, Pittsburgh, Pa.

Pages: 11    Published: Jan 1980

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Abstract

The classical photoconductivity decay method for measuring recombination lifetime was improved by using a 1.06-μm pulsed laser source to generate a spacially uniform excess minority carrier concentration. The accuracy of measurements on thin wafers was significantly enhanced by using an etched, well-characterized, low recombination velocity surface in place of the normally lapped surface. Lifetime measurements were performed both before and after thermal heat treatment, and final deionized water rinsing was identified as a crucial step. A mathematic model was developed to guide the development of decontamination procedures that would optimize the retention of lifetime. Particulate contamination in the deionized water was found to be the factor limiting the post-heat-treatment lifetime.