Implementation of Ambipolar Polysilicon Thin-Film Transistors with Nickel Silicide Schottky Junctions by Low-Thermal-Budget Microwave Annealing.

In this study, the efficient fabrication of nickel silicide (NiSi x ) Schottky barrier thin-film transistors (SB-TFTs) via microwave annealing (MWA) technology is proposed, and complementary metal-oxide-semiconductor (CMOS) inverters are implemented in a simplified process using ambipolar transistor properties. To validate the efficacy of the NiSi x formation process by MWA, NiSi x is also prepared via the conventional rapid thermal annealing (RTA) process. The Rs of the MWA NiSi x decreases with increasing microwave power, and becomes saturated at 600 W, thus showing lower resistance than the 500 °C RTA NiSi x . Further, SB-diodes formed on n-type and p-type bulk silicon are found to have optimal rectification characteristics at 600 W microwave power, and exhibit superior characteristics to the RTA SB-diodes. Evaluation of the electrical properties of NiSi x SB-TFTs on excimer-laser-annealed (ELA) poly-Si substrates indicates that the MWA NiSi x junction exhibits better ambipolar operation and transistor performance, along with improved stability. Furthermore, CMOS inverters, constructed using the ambipolar SB-TFTs, exhibit better voltage transfer characteristics, voltage gains, and dynamic inverting behavior by incorporating the MWA NiSi x source-and-drain (S/D) junctions. Therefore, MWA is an effective process for silicide formation, and ambipolar SB-TFTs using MWA NiSi x junctions provide a promising future for CMOS technology.