ABSTRACTThe N2-SiH4 rf glow-discharge plasma has been analyzed by line-of-sight mass spectrometry of species impinging on the deposition electrode, including N atoms. Properties of SixNyHz films deposited from this plasma have been examined. At high rf power and low SiH4/N2, almost all of the SiH4 is consumed by reaction with N atoms at the film surface and becomes incorporated into the film. No Si-N precursor species are seen in the gas phase. This is in contrast to the NH3-SiH4 plasma, where the Si(NH2)3 radical is the key precursor. If power is insufficient or SiH4 flow is excessive, Si2Hm species are generated in the plasma. Under optimized conditions, films slightly N-rich with no Si-H bonding and only 7% H (as N-H) can be deposited at high rate. The film tensile stress of the NH3 process is absent in the N2 process due to the lesser amount of condensation that takes place during deposition. However, trench coverage is much better in the NH3 process.
