We have developed a procedure to optimize electron mobility and leakage currents in MOSFETs fabricated in laser recrystallized polysilicon films on SiO//2. A shaped laser beam was used to obtain grain boundaries aligned with the current flow in MOS transistors. To suppress grain boundary diffusion, rapid thermal annealing replaced all high temperature processing steps subsequent to source and drain implantation. By combining these two approaches, functional transistors as short as 1. 5 mu m were obtained, and also 2 mu m-channel 19-stage ring oscillators with 115 psec/stage propagation delay.