SILICON-WAFER BONDING STUDIED BY INFRARED-ABSORPTION SPECTROSCOPY

The interface of hydrophilic and hydrophobic Si wafers joined at room temperature is studied using multiple internal transmission infrared absorption spectroscopy as a function of 30-min annealing steps in N2 atmosphere up to 1100°C. For hydrophilic wafers, water molecules are observed up to 300°C, silanol groups up to 900°C, and hydrogen up to 1000°C. The absence of water spectral features above 300°C implies that, if present, water molecules are mostly oriented in a plane parallel to the interface. For the hydrophobic wafers, the temperature dependence of the Si-H stretch spectra shows that the majority of H does not participate in the bonding, pointing to the role of impurities or defects. © 1994 American Institute of Physics.