Fabrication of thin film transistors using a Si/Si1-xGex/Si triple layer film on a SiO2 substrate

Abstract

A novel approach that can reduce the thermal budget in the fabrication of thin film transistors (TFT's) using a Si/Si0.7Ge0.3/Si triple film as an active layer was proposed. The crystallization behavior of the triple film was described and device characteristics of Si/Si0.7Ge0.3/Si TFT's were compared with those of Si TFT's and of SiGe TFT's. The triple film was completely crystallized only after a 25-h anneal at 550 degrees C, N-channel polycrystalline Si/Si0.7Ge0.3/Si TFT's had a field-effect mobility of 57.9 cm(2)/Vs and an I-on/I-off ratio of 5.7 x 10(6). This technique provides not only a shorter time processing capability than Si TFT's technology but also superior device characteristics compared to SiGe TFT's.