In a miniaturized complete CMOS SRAM of a TFT load type, a field effect thin-film transistor (TFT) can achieve stable reading and writing operation of a memory cell and can reduce power consumption thereof. The field effect thin-film transistor formed on an insulator includes an active layer and a gate electrode. The gate electrode is formed on a channel region of the active layer with a gate insulating film therebetween. The active layer is formed of a channel region and source/drain regions. The channel region is formed of a monocrystal silicon layer and does not includes a grain boundary. The source/drain regions is formed of a polysilicon layer. The channel region has a density of crystal defects of less than 10.sup.9 pieces/cm.sup.2. The thin film transistor shows an ON current of 0.25 .mu.A/.mu.m per channel width of 1 .mu.m and an OFF current of 15 fA/.mu.m. The thin-film transistor can be applied to a p-channel MOS transistor serving as a load transistor in a memory cell of a CMOS type SRAM.