Article ID Journal Published Year Pages File Type
1664784 Thin Solid Films 2015 5 Pages PDF
Abstract

•Fabrication of transparent SiNx films using surface-wave-plasma deposition.•Si-rich-SiNx films contain suboxides that may decrease both transparency and stability.•Using high NH3/SiH4 gas ratio results in transparent and stable Si3N4.

Highly transparent silicon nitride films with a low absorption coefficient of only 200 cm- 1 or lower were prepared under high NH3/SiH4 source gas ratio conditions at 80 °C or lower temperature using surface wave plasma chemical vapor deposition (SWP-CVD). Rutherford backscattering measurements indicated that a silicon nitride structure Si3Nx (x > 5) with excess nitrogen could be prepared with the SWP-CVD method under high NH3/SiH4 source gas ratio conditions. X-ray photon spectroscopy (XPS) analysis provided verification that the excess nitrogen combined with the oxygen contained in the SiNx film during low-temperature film formation and that the atomic ratio of Si and N was almost stoichiometric, i.e., Si3N4.XPS study also revealed that the Si3N< 4 structure contained suboxides, which presence may reduce the transparency of the films. In contrast, suboxides were not observed in the Si3N4 structure obtained under high NH3/SiH4 source gas ratio conditions. Fourier-transform infrared spectroscopy study confirmed that the SiNx film becomes more stable when the SiNx structure approaches the stoichiometric ratio. Achieving a near-transparent Si3N4 structure requires a sufficient amount of N atoms in the periphery of the Si atom, i.e., an adequate amount of NH3 is necessary in the presence of the SiH4.

Related Topics
Physical Sciences and Engineering Materials Science Nanotechnology
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