HIGH-PERFORMANCE THIN-FILM TRANSISTORS FABRICATED USING EXCIMER-LASERPROCESSING AND GRAIN ENGINEERING

High-performance polysilicon thin-film transistors (TFT's) are fabrica ted using an excimer laser to recrystallize the undoped channel and do pe the source-drain regions, Using a technique we call ''grain enginee ring'' we are able to control grain microstructure using laser paramet ers, Resulting polysilicon films are obtained with average grain sizes of similar to 4-9 mu m in sub-100 nm thick polysilicon films without substrate heating during the laser recrystallization process; Using a simple four-mask self-aligned aluminum top-gate structure, we fabricat e TFT's in these films, By combining the grain-engineered channel poly silicon regions with laser-doped source-drain regions, TFT's are fabri cated with electron mobilities up to 260 cm(2)/Vs and on/off current r atios greater than 10(7). To our knowledge, these devices represent th e highest performance laser-processed TFT's reported to date fabricate d without substrate heating or hydrogenation.