Impact of Underwater Laser Annealing on Polycrystalline Silicon Thin-Film Transistor for Inactivation of Electrical Defects at Super Low Temperature

We propose underwater laser annealing (WLA) for the inactivation of electrical defects in polycrystalline silicon thin-film transistors (poly-Si TFTs) at super low-temperature. This technique can reduce the temperature of inactivation process drastically, and it requires only UV laser and deionized water. We performed WLA after the fabrication of top-gate type poly-Si TFTs. After WLA, the field-effect mobility of poly-Si TFTs increased from 52 to 72 cm
$^{2}/{\hbox{V}}\cdot{\hbox{sec}}$
. The TFT surface was exposed to water vapor which was generated by laser irradiation, resulting that electrical defects were inactivated by active species in water vapor.