Molecular hydrogen formation in hydrogenated silicon nitride

Hydrogen is released from hydrogenated silicon nitride ( Si N x : H ) during thermal treatments. The formation of molecular hydrogen ( H 2 ) in Si N x : H layers with low mass density is confirmed by Raman spectroscopy. However, no H 2 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 Si N x : H antireflection coatings.