Abstract
The fundamental mechanism underlying the hydrogen exfoliation phenomenon at the damaged layer in Si was investigated. We studied the distribution of the defects as a function of implanted hydrogen dose and clarified the key role of defects in the action of exfoliation. A damaged layer formed by high dose hydrogen implantation in a silicon wafer was observed by cross sectional transmission electron microscopy (XTEM). In the damaged layer caused by hydrogen implantation, (100) defects and (111) defects were observed. The density and size of defects were analyzed and compared with the hydrogen profile obtained by second ion mass spectroscopy (SIMS). The defect distribution was in agreement with the hydrogen concentration obtained by SIMS. The density of (111) defects became higher as the area from the surface deepened, and the sizes of (100) defects and (111) defects grew larger. These results indicate that hydrogen in (111) defects moves toward (100) defects at projection range, and the pressure of hydrogen gas caused by annealing leads to the exfoliation.
