Effects of hydrogen implantation temperature on ion-cut of silicon

Abstract

We have studied the effect of ion implantation temperature on the nature of cleavage and layer transfer, and the electrical properties in hydrogen implanted p-Si. The lattice damage and the hydrogen concentration in the as-implanted Si and transferred Si films were analyzed with elastic recoil detection, respectively. Implantations performed at −140 °C [low temperature (LT)] and room temperature (RT) resulted in a variation in the thickness and surface morphology of the transferred layers. The transferred layer from room temperature hydrogen ion implantation was both thicker and atomically smoother than the transferred layer produced by −140 °C hydrogen implantation. The as-transferred layer obtained from RT-implanted p-Si wafer was n-type, but converted to p-type after annealing at 650 °C or higher. The transferred layer obtained from LT-implanted Si wafer was highly resistive even after high temperature annealing. These variations were observed to be correlated with the damage profiles measured by ion channeling; channeling data showed that the room temperature implantation provided a deeper and narrower damage distribution than that obtained from the −140 °C implantation. The nature of the implantation damage was evaluated with the aid of IR spectroscopy and was found to consist of Si–H defects. The type and population of these defects were observed to be dependent on the ion implantation temperature. In both room temperature and −140 °C implantations, the presence of the implantation damage facilitated the nucleation of Si–H defects that developed into H platelets, which were the precursor defects for the cleavage and the layer transfer.