Rapid Joule Heating of Metal Films Used to Fabricate Polycrystalline Silicon Thin Film Transistors

Abstract

We report fabrication of p-channel polycrystalline silicon thin film transistors (poly-Si TFTs) at a low temperature using a rapid crystallization joule heating method. Fifty-nm-thick silicon films were crystallized via 300-nm-thick SiO2 intermediate layers by heat diffusion from joule heating induced by electrical current flowing in chromium strips. The maximum grain size was about 100 nm. Oxygen plasma of 13.56 MHz at 100 W, 130 Pa and 250°C was applied for 5 min for defect reduction in the polycrystalline silicon films. Heat treatment at 200°C with 1.3×106-Pa-H2O vapor was applied for 3 h to improve electrical properties of SiOx gate insulator. TFTs had a high carrier mobility of 204 cm2/V·s and a low threshold voltage of -2.1 V.