High-Pressure H2O Vapor Heat Treatment Used to Fabricate Poly-Si Thin Film Transistors

Abstract

High-pressure H2O vapor heat treatment was applied to reduction of defect states of silicon films and SiOx/Si interfaces in the fabrication of n-channel polycrystalline silicon thin film transistors (poly-Si TFTs). A carrier mobility of 170 cm2/V·s and a low threshold voltage of 2.4 V were achieved by heat treatment at 260°C with 1.3×106 Pa H2O vapor for 3 h applied to 25-nm-thick silicon films crystallized by the irradiation of a 30-ns-pulsed XeCl excimer laser at 280 mJ/cm2. Additional high-pressure H2O vapor heat treatment after TFT fabrication further improved them to 620 cm2/V·s and 1.7 V, respectively.