The effect of copper diffusion on deep states in oxidized and oxygen induced stacking faulted P-type RTA silicon

Abstract

Defect impurity levels in rapid thermal annealed (RTA) p-type Czochralski (Cz) silicon and the effect of copper diffusion on oxidized and oxygen induced stacking faulted (OISFed) RTA samples have been examined by deep level transient spectroscopy (DLTS). The surface morphology of these samples were analysed by scanning electron microscopy (SEM) and the optical properties of the states present in the same samples were investigated by a photoluminescence (PL) system. Hole traps of 0.23 eV and 0.27 eV have been detected in clean RTA samples. States of 35 eV and 0.42 eV have been consistently detected as a pair when the diffusion cycle of copper in oxidized RTA samples is greater than 1 minute. From DLTS, PL and SEM studies, the 0.35 eV center was related to 90/spl deg/ dislocations produced during copper diffusion. Substitutional copper atoms behaved as triple acceptors at 0.42 eV. Oxygen induced stacking faults (OISFs) with average penetration depth of one micrometer have been generated at a density of 2/spl times/10/sup 6/ cm/sup -2/ in RTA sample. The simple PL spectrum dominated by the D1 line and a single broad DLTS spectrum has been observed in clean OISF samples. This broad DLTS signal has a trap level of 393-456 meV at a peak temperature of 201-212/spl deg/K. The diffusion of copper into the samples reduced the D1 line intensity very significantly and modified the capture properties of OISF related states. New states appeared when the diffusion cycle of copper was greater than 1 minute. Any heat treatment at 410/spl deg/K above 15 minutes increased the trap concentrations, and one of the states (510 meV) became dominant. This state was related to the formation of copper rich silicide which produced extrinsic dislocation loops. >