SiO2 formation by thermal evaporation of SiO in oxygen atmosphere used to fabrication of high performance polycrystalline silicon thin film transistors

Abstract

A reactive evaporation of SiO in an oxygen atmosphere was investigated for forming a good interface of SiO2/Si. SiO2 films are formed at room temperature by evaporation of a SiO powder in an oxygen atmosphere with a flow rate of 2 sccm at a pressure of 1×10−4 Torr. The interface trapping density at SiO2/Si was lower than 5×1010 cm−2 eV−1. n- and p-channel Al-gate polycrystalline silicon thin film transistors (poly-Si TFTs) were fabricated at 270 °C with the present SiO2 films as a gate oxide and laser crystallized poly-Si films formed using a pulsed XeCl excimer laser. They showed good characteristics of a low threshold voltage of 1.1 V (n-channel) and −1.2 V (p-channel), and a high carrier mobility of 450 cm2/V s (n-channel) and 270 cm2/V s (p-channel).