Crystallization of silicon thin films by current-induced joule heating using a tungsten overcoat

A modified crystallization process using current-induced joule heating under vacuum is presented. A thin layer of high temperature resistant tungsten was sputtered on the amorphous silicon as the conducting and annealing medium. The thin film thickness was measured by α-stepper. The high current density provided effective means in crystallizing the amorphous silicon layer. The crystalline morphology was studied by scanning electron microscopy (SEM) after Secco-etch, transmission electron microscopy (TEM), and x-ray diffraction (XRD), under different annealing conditions. The grain size was controlled in the range of 0.1-0.5 um and could be increased with annealing time. No tungsten silicide was found. Some defects were formed due to electron-migration effect near the electrodes.