P Channel thin film transistor and complementary metal–oxide–silicon inverter made of microcrystalline silicon directly deposited at 320°C

Abstract

We report a p channel thin film transistor (TFT) made of directly deposited microcrystalline silicon (μc-Si). The μc-Si channel material is grown by plasma-enhanced chemical vapor deposition (PECVD) using dc excitation of a mixture of SiH 4, SiF 4 and H 2, in a process similar to the deposition of hydrogenated amorphous silicon (a-Si:H). The deposition temperature for the μc-Si is 320°C and the highest post-deposition TFT process temperature is 280°C. By integrating this p TFT on a single μc-Si film with an n channel TFT, we fabricated a complementary metal–oxide–silicon (CMOS) inverter of deposited μc-Si. The p channel μc-Si TFT represents a breakthrough in low-temperature Si TFT technology because p channel TFTs of a-Si:H have not been available to date. The integrated CMOS inverter is the building block of a new digital circuit technology based on directly deposited μc-Si.