Thin film transistors (TFTs) are fabricated inside a large, location-controlled, silicon grain, fabricated with the grain-filter method. In a first experiment TFTs with high field-effect mobility for electrons of 430 cm2/Vs are fabricated. The off-current and subthreshold swing have high values of 60 pA and 1.2 V/dec, respectively. The grain-filter is improved by doping the channel and by planarizing the grain-filter by chemical mechanical polishing (CMP). TFTs fabricated in CMP-planarized grain-filters have mobility, off-current, and subthreshold swing of 430 cm2/Vs, 0.3 pA, and 0.29 V/dec, respectively, which compares well with the characteristics for SOI TFTs.