Polycrystalline Silicon Thin-Film Transistors Fabricated by Defect Reduction Methods

摘要

The fabrication of n-channel polycrystalline silicon thin film transistors is reported. Defect reduction of pulsed laser crystallized polycrystalline silicon films using 13.56 MHz oxygen plasma treatment at 250 ℃ and 130 Pa for 5 min with a RF power of 100 W achieved an effective carrier mobility of 251 cm~2/Vs and a threshold voltage of 3.2 V. A 1.3xl0~6Pa-H_2O vapor heat treatment at 260 ℃ for 3 h achieved an effective carrier mobility of 170 cm~2/Vs and a threshold voltage of 2.4 V. Combination of these defect reduction treatments achieved an effective carrier mobility of 830 cm~2/Vs and a threshold voltage of 1.5 V. H_2O vapor heat treatment after TFT fabrication furthermore improved the electrical properties. A very high effective carrier mobility and a low threshold voltage of 1200 cm~2/Vs and 1.1 V, respectively, were achieved.