Changes in interfacial bonding energies in the chemical activation of GaAs surfaces

The bonding chemistry and the role of the additional HCl-based prebonding treatment when combined with ozone and oxygen plasma treatments on the GaAs/GaAs direct bonding were investigated using multiple internal transmission Fourier transform infrared spectroscopy (MIT-FTIR) and atomic force microscopy (AFM). The results showed that the additional HCl-based pretreatment led to an increased bonding strength and a qualitative reduction in the void density. The removal of the initial native oxide facilitates the diffusion of water to the GaAs wafer surface where it can react to form primarily Ga-based oxides, leading to a substantially increased bond strength compared to those without the removal of interfacial native oxide.