Mechanical understanding of 100 mm InP and GaAs direct bonded heterostructure

Indium phosphide (InP) and gallium arsenide (GaAs) 100 mm wafers were bonded by direct wafer bonding in a cleanroom environment. Unexpected high bow values measured at room temperature after different thermal annealings are the focus of this study. Various experiments such as in situ bow measurements, surface XPS characterizations and TEM cross section observations highlight the key mechanisms that evolve with temperature. Over 200 °C, gallium oxide is formed at the bonded interface due to the presence of water that is trapped at the InP/GaAs interface during the hydrophilic bonding. These results allow us to explain the heterostructure debonding/re-bonding behavior.