Effects of grain boundaries on laser crystallized poly-Si MOSFET´s

Data are reported for n-MOSFET´s fabricated in laser crystallized poly-Si on amorphous insulating substrates. The dependence of electrical characteristics on the effective channel length in the range of 100 to 0.3 µm and on channel width from 120 to 20 µm is presented. The electron surface mobility is found to increase as the channel length is reduced, approaching that of devices in single-crystalline silicon. The source-to-drain leakage current, negligible for long channels, rapidly increases for channels shorter than ≃ 3 µm. This excessive current results from grain boundary diffusion of As from source and drain during high temperature fabrication steps.