Low temperature germanium-silicon on insulator thin-film transistor

Abstract

Abstract MOS transistors are formed in thin films of Ge/Si alloys (Ge x Si 1-x ). According to the process of the present invention, polycrystalline films of Ge/Si are deposited using commercially-available LPCVD equipment, which in the preferred process uses silane and germane as the sources of Ge and Si. The deposited Ge x Si 1-x films are polycrystalline at temperatures for processing down to as below 400° C., and the films can be doped heavily by ion implantation and annealing at temperatures as low as 600° C. to give high mobility and dopant activation yielding very low resistivity. By carrying out the annealing step in the formation of the thin film transistors in the temperature range of 400° to 500° C., the films provide very large grain size, minimizing the impact of grain boundaries in the polycrystalline films where the thin film transistors are to be formed. As a result, thin film MOS transistors are fabricated at temperatures below 500° C., and as low as 400° C., by using Ge x Si 1-x deposition and doping technology. The resulting transistors have significantly improved electrical characteristics compared to thin film transistors fabricated in silicon films utilizing standard processing techniques.

Inventors

• 👤 Krishna C. Saraswat
• 👤 Tsu-Jae King

Bibliographic Details