Revealing the mechanism of interfacial adhesion enhancement between the SiO2 film and the GaAs substrate via plasma pre-treatments

The formation mechanism of a highly adherent silicon dioxide (SiO2) film on gallium arsenide (GaAs) substrate by plasma enhanced chemical vapor deposition (PECVD) is proposed. Ar, N2, and NH3 were used as pre-treatment gas to improve the interfacial adhesion. The interfacial adhesion was measured by the cross-cut tape test. By the measurement of spectroscopic ellipsometry and x-ray photoelectron spectroscopy (XPS), it is revealed that nitrogen plasma pre-treatment had formed a very thin GaN transition layer on the surface, which was responsible for the improvement of interfacial adhesion. XPS depth-profiling further confirmed various pre-treatment gases generate plasma mixtures and form thin film layers with different compositions on the GaAs surface. These layers have a significant impact on the adhesion of the subsequently prepared SiO2 film. The primary mechanism for improving interfacial adhesion is the renovation of the substrate composition via plasma pre-treatment by PECVD, which forms a transition layer of nitrides that eliminates the negative effects of oxides on adhesion. This study reveals the mechanism of interfacial adhesion enhancement between SiO2 film and GaAs substrate, which is of significant importance in fabricating high-performance and reliable semiconductor devices.