Effect of hydrogen dilution on the properties and bonding in plasma-deposited silicon nitride

A study was done on the effects of hydrogen dilution on the properties and structure of silicon nitride films deposited by plasma-enhanced chemical vapor deposition from NH3/SiH4 mixtures. Results show that the addition of small amounts of hydrogen at a fixed NH3/SiH4 ratio increased the excess Si in the film accompanied by a corresponding increase in the Si-H/N-H bonding ratio. The films became more stoichiometric with significant changes in the hydrogen bonding at higher dilution.