Enhancement of removing OH bonds from low-temperature-deposited silicon oxide films by adding water vapor into NH₃ gas annealing at 130 °C

Abstract In this study, it is revealed that annealing with water-vapor-added NH 3 gas (water-added NH 3 ) is more effective than with dry NH 3 at removing residual OH bonds in silicon oxide (SiOx) films deposited by atmospheric chemical vapor deposition with an organic silicon source. Fourier transform infrared spectra showed that the reduction amount of OH bonds using the water-added NH 3 was ∼4 or ∼1.3 times larger than using the conventional dry N 2 or dry NH 3 mixed with N 2 gas without water, respectively. This result is somewhat surprising because water is a potential candidate as a source of OH. The effect of water vapor on OH bond removal can be explained by considering the following three factors; the first is that low-temperature SiOx films are constrained somewhat, the second is that strained Si-O-Si bonds are in a higher or more unstable energy state than strain-free ones, and the third is that highly strained bonds are easily hydroxylated to form Si-OH bonds.