High-temperature healing of interfacial voids in GaAs wafer bonding

Artificial voids were introduced at bonding interfaces to study how processing parameters affected the healing mechanism of interfacial voids in GaAs wafer bonding. These voids were created by placing unpatterned wafers in contact with topographically patterned wafers. During the bonding process, crystallites formed within these voids and corresponded to bonded regions within the voids. Their formation depended strongly on the height of the surface irregularities at the wafer interfaces. When the void depth (h) was ≥200 nm, most of the crystallites were diamond shaped. The edges of the diamond features were elongated in the 〈100〉 direction. On the other hand, when the void depth was small (h≤70nm), dendrites grew quickly in the 〈110〉 direction.