Polysilicon Thin Film Transistors with Cobalt amd Nickel Silicide Source and Drain Contacts

Polysilicon n-type thin film transistors have been fabricated with self-aligned cobalt and nickel silicide contacts to the source and drain regions. The sheet resistance of the source and drain without silicide is above 200 Ω/‪. The cobalt and nickel silicide films have sheet resistance below 30 Ω/‪. The contact resistance of the silicided devices is also much lower. The reduced extrinsic resistance is shown to improve the current in the “on” state, without increasing the leakage current. This study includes examination of cobalt and nickel silicidation on thin polysilicon films at temperatures compatible with polysilicon TFT-LCD processes.