A high-selectivity native oxide removal process for native oxide free processes

Abstract

In this work, the removal of native oxide on monocrystalline Si and poly-Si was investigated. It was found that by reducing the concentration of the HF solution, the loss of thermal oxide and TEOS can be reduced almost to thicknesses which are equivalent to the native oxide thickness which has to be removed. To accelerate the reaction, higher temperatures can be used. In the case of poly-Si, it was found that the etching of the last monolayer of the native oxide is much slower than for monocrystalline Si. In the poly-Si case, this can be easily accelerated by the use of higher temperatures.<>