Poly-Si TFT’s were fabricated on the glass substrate by the Metal Induced Lateral Crystallization(MILC). Before deposition of the active a-Si thin films(1000 Å), the glass substrate was pretreated in three different ways such as oxidation of a-Si(100 Å), oxide buffer layer deposition(1000 Å), and ion mass doping of the glass substrates. The leakage current at reverse bias could be reduced by one order of magnitude by the substrate pretreatment. Field effect mobility of n-channel TFT’s was 108cm2/Vsec, subthreshold slope and on/off current ratio were 0.7 V/dec. and about 106, respectively.