SEDL / STP / STP990-EB / STP26049S

Process - Induced Influence on the Minority — Carrier Lifetime in Power Devices

Khanna, VK
research scientists, Semiconductor Devices Area, Central Electronics Engineering Research Institute, Pilani, Rajasthan

Thakur, DK
research scientists, Semiconductor Devices Area, Central Electronics Engineering Research Institute, Pilani, Rajasthan

Jasuja, KL
research scientists, Semiconductor Devices Area, Central Electronics Engineering Research Institute, Pilani, Rajasthan

Khokle, WS
research scientists, Semiconductor Devices Area, Central Electronics Engineering Research Institute, Pilani, Rajasthan

Pages: 15    Published: Jan 1989

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Abstract

Carrier lifetime has been studied as a function of process conditions for power semiconductor devices. The lifetime measurements have been done to see the influence of minority-carrier lifetime on device characteristics under different process conditions such as KOH etching, DI water rinse, deep diffusions, thermal oxidation, phosphorous diffusion and gold diffusion. Open Circuit Voltage Decay (OCVD) and Surface Photovoltage (SPV) techniques have been used to measure minority-carrier lifetime.

It has been observed that the starting-wafer lifetime tends to change strongly during the course of fabrication processes and shows a dependence on the injection level. The typical curves show two-fold effects : (i) The effect of traps and (ii) The carrier density. The injection-level dependence of lifetime is attributed to heavy-doping effects in silicon, and in the absence of traps, is described by an empirical relationship.