SPATIAL DISTRIBUTIONS OF INDUCED TRAPS IN SILICON BY RAPID THERMAL-PROCESSING

Spatial distributions of induced traps in n-type silicon by rapid thermal processing (RTP) have been studied by deep-level transient spectroscopy (DLTS). RTP has been performed at 1000°C for 10 s in flowing N2. Four electron traps A1 (Ec - 0.18 eV), A2 (Ec - 0.25 eV), A3 (Ec - 0.36 eV) and A4 (Ec - 0.52 eV) are found to be induced by RTP. The present work concentrates on trap A4, since this trap is thought to act as the efficient generation-recombination center. In order to allow the rapid estimation of trap A4 for a large number of samples, DLTS has been performed in the time domain at the constant temperature. It is found that trap A4 shows a W-shaped pattern along the <110 > and <100 > directions. It is thought that this peculiar distribution corresponds to the thermal stress induced during RTP, due to the temperature nonuniformity across the wafer. The effect of the oxygen concentration in wafers on the production of trap A4 has also been reported. © 1990.