High-Mobility Poly-Si Thin Film Transistors Fabricated on Stainless-Steel Foils by Low-Temperature Processes Using Sputter-Depositions

High mobility n- and p-channel polycrystalline Si thin film transistors (poly-Si TFTs) are successfully fabricated on flexible stainless-steel foils through low-temperature processes (≦200°C). In the low-temperature process, all films in the poly-Si TFT including active Si and gate SiO 2 films are deposited by glow-discharge sputtering and the Si films are crystallized by KrF excimer laser irradiation. Resulting n- and p-channel poly-Si TFTs show excellent characteristics of mobility of 106 cm 2 /V·s and 66 cm 2 /V·s, respectively. Moreover, they show low off-currents of 1×10 -10 A and on/off current ratios as high as 1×10 6 . Thus, these poly-Si TFTs are very promising for driver circuits and switching devices in novel flat panel displays of lightweight and mechanically strong liquid crystal displays and light emitting displays.