Direct Bonding of Ge-Ge Using Epitaxially Grown Ge-on-Si Wafers

摘要

High quality germanium (Ge) epitaxial film grown directly on silicon (001) substrate is used to study the characteristics of direct Ge-Ge bonding. The Ge epilayer on Si(100) is found to be hydrophilic in nature and storage test for seven days in ambient has no affect on its surface contact angle. Analysis shows that the Ge-Ge bond strength (mJ/m~2) is directly dependent on the annealing temperature (°C). At room ambient, the bond strength of the bonded wafer pair is ~55 mJ/m~2 and increases to ~2460 mJ/m2 subjected to annealing at 300°C in N_2 ambient for 3 hours. Also, the transmission electron microscopy (TEM) cross-sectional view at the bonding interface indicates that the bond is seamless and no micro-void is observed.