Dependence of silicon-on-insulator transistor parameters on oxygen implantation temperature

Silicon‐on‐insulator films have been formed by high‐dose oxygen implantation. Thermal donors, resulting from the residual oxygen content of the single crystal silicon region of the films, have been found to influence the electrical performance of transistors fabricated in them. The amount of oxygen in the active region of the silicon layer is strongly dependent on the oxygen implantation temperature. As the temperature is decreased below 500 °C an increasing thickness of oxygen‐rich polycrystalline silicon is formed between the single crystal region and the buried oxide, causing the oxygen concentration in the single crystal region (and hence the thermal donor activity) to fall. As well as providing thermal donors, the residual oxygen also causes a lattice strain which increases the electron mobility.