Molecular hydrogen formation in hydrogenated silicon nitride

Hydrogen is released from hydrogenated silicon nitride (SiNx:H) during thermal treatments. The formation of molecular hydrogen (H2) in SiNx:H layers with low mass density is confirmed by Raman spectroscopy. However, no H2 is observed in layers with a high mass density despite clear evidence that hydrogen diffuses through those layers. Therefore hydrogen migrates in those layers in a different form. This is consistent with the observed improvement of the hydrogen passivation of silicon substrates using thermally treated high density SiNx:H antireflection coatings.