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).