Roughness and stability of silicon on insulator surfaces

The feasibility of low temperature processes (below 800 °C) to obtain in situ atomically clean and smooth surfaces on (100) oriented silicon on insulator material (SOI) with negligible variation of the top Si film thickness was tested. These steps were characterized using low-energy electron diffraction and atomic force microscopy supplemented by conductivity measurements. The most promising method for obtaining atomically smooth and continuous SOI films is the evaporation of Si at 750 °C at a flux of 0.15 ML/min. For lower rates [113]-oriented pits are formed within the SOI layer. It turned out that mobile and volatile oxide formation at the Si/SiO2 interface in these materials can occur already at temperatures below 1000° C, leading to the destruction of the buried oxide layer.