Behavior of indium in thin SOI films

The behavior of indium implanted in silicon-on-insulator (SOI) material is explored by using SIMS analysis to obtain the doping concentration profile as a function of the silicon film thickness for a fixed implant depth, and as a function of the implant depth for a fixed silicon film thickness. Based on the experimental data, the following observations can be made. Indium can be highly mobile and can diffuse throughout the buried oxide. As a result, there is a dopant depletion zone near the buried oxide interface. The indium doping profile can be practically invariant under certain implant conditions in thicker films. As a result of indium's highly mobile nature, a lower temperature process is necessary to maintain the as-implanted indium profile in thin-film SOI transistors.