Application of Rapid Joule Heating Method to Fabrication of Polycrystalline Silicon Thin Film Transistors

Abstract

We report the rapid crystallization of silicon films with a joule heating method and its application to the fabrication of n-channel and p-channel polycrystalline silicon thin film transistors (poly-Si TFTs). Crystallization of 50-nm-thick silicon films and activation of dopant atoms were successfully achieved by rapid heat diffusion via 300-nm-thick SiO2 intermediate layers from joule heating induced by electrical current flowing in chromium strips. The average grain size was about 100 nm in crystallized films. A high electrical conductivity of 2050 S/cm was achieved for 1.3×1021-cm-3-phosphorus doped silicon films. TFTs have a carrier mobility and a threshold voltage of 570 cm2/Vs and 1.8 V for n-channel TFTs, and 270 cm2/Vs and -2.8 V for p-channel TFTs, respectively.