<title>Rapid thermal processing induced defects and gettering effects in silicon</title>

Abstract

In recent years rapid thermal processes (RTPs) have been widely studied to replace conventional processing. The use of this technique which is less time and energy consumption than classical thermal treatments can be widespread if in one hand the origin of process induced defects can be clarified and in the other hand the gettering of impurities in silicon can be effective. Up to now the RTP introduced defects was inherently correlated to the " quenching" step due to the fast cooling rate (typically around 100C/s) and the time duration of the order of seconds to tens of seconds was generally considered to be inappropriate to increase by gettering the purity of materials in the active region. The reason involved was the time scale which would not allow the impurities to migrate to the gettering sites given the diffusity values observed and measured in conventional diffusion studies. In our study we will present results showing that Deep Level Transient Spectroscopy (DLTS) is particularly efficient to identify the origin of RTP related defects. We found that they are mostly related to residual impurities present in the as-grown silicon wafers or unintentionally introduced during high-temperature processing steps. For one particular material an activation of a specific residual metallic-impurity was observed in the temperature range 800-1000C. This impurity can be returned to an electrically inactive precipitated form by classical thermal annealing (CTA) with a slow