PHASE-TRANSFORMATION MECHANISMS INVOLVED IN EXCIMER-LASER CRYSTALLIZATION OF AMORPHOUS-SILICON FILMS

We have investigated the phase transformation mechanisms and the resul ting microstructures of excimer laser-induced crystallization of amorp hous Si films on SiO2. It is shown that the process can be characteriz ed into two major regimes, based on the dependence of the grain size a nd the melt duration as a function of the incident energy density. It is found that at the transition between the two regimes, exceedingly l arge grain-sized polycrystalline films can be obtained. We call this t he super lateral growth phenomenon, and propose a model based on liqui d-phase regrowth from the residual solid seeds when near-complete melt ing of the Si film occurs.