Investigation of Surface Blistering and Exfoliation in Germanium Induced by Hydrogen Molecular Ion Implantation

This study investigated the effects of thermal budget on the surface blistering and exfoliation behavior in germanium due to hydrogen molecular ion implantation. Germanium wafers were implanted with 200 keV H2+ ions to a fluence of 2.5×1016 ions/cm2 and followed by furnace annealing treatments with various thermal budget. Characteristic analyses were conducted using optical microscopy (OM), secondary ion mass spectroscopy (SIMS), and cross-sectional transmission electron microscopy (XTEM). The results of the OM-measured average number density, diameter, and covered-area fraction of both optically-detectable blisters and craters suggested an optimal condition of 410 oC, 1 hr. The XTEM-examined images and the SIMS-measured hydrogen and oxygen depth profiles also confirmed that the average depth of micro-cracks correlated closely to the positions of peak hydrogen-trapping concentration and peak oxygen-trapping concentration rather than that of peak hydrogen concentration.