SEDL / STP / STP712-EB / STP35128S

Minority Carrier Lifetime Degradation in Silicon Due to Thermally Generated Dislocations

Liang, AY
Senior device engineer and senior technical staff member, Motorola Inc. Semiconductor Group, Semiconductor Research and Development Laboratories, Phoenix, Ariz.

Varker, CJ
Senior device engineer and senior technical staff member, Motorola Inc. Semiconductor Group, Semiconductor Research and Development Laboratories, Phoenix, Ariz.

Pages: 13    Published: Jan 1980

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Abstract

Minority carrier lifetime uniformity is examined in processed silicon wafers containing thermally induced dislocations. The experimental method, which utilizes transient and steady-state measurements, includes open-circuit voltage decay (OCVD), junction current recovery (JCR), forward voltage drop, V^F, and current-voltage characteristics on small-area p⁺-n diode arrays. The observation is made that the minority carrier lifetime profiles correlate with the distribution of dislocations revealed by preferential chemical etching and that general agreement exists among these measurement methods regarding the spatial uniformity of carrier lifetime. The authors conclude that the processing-induced dislocations degrade the carrier lifetime and possibly reduce the carrier mobility. Moreover, it is clearly demonstrated that a simple direct-current measurement such as V^F can be used as an indicator of the lifetime variations across the processed wafer, particularly when a correlation between the minority carrier lifetime, τ, and V^F is established experimentally.