Duty ratio impact on SiN films deposited in SiH4-NH3 plasma at room temperature

Silicon nitride (SiN) films were deposited by using pulsed plasma-enhanced chemical vapor deposition system. The experiments were conducted from SiH4 and NH3 plasma at room temperature. The duty ratio was varied in the range 40–90%. Duty ratio-induced ion energy diagnostics was conducted using a non-invasive ion energy analyzer. Ion energy variables collected include a high ion energy (Eh), a low ion energy (El), a high energy flux (Nh), a low ion energy flux (Nl). Their various ratios were calculated to examine relationships between ion energy and film properties, including deposition rate, refractive index, and surface roughness. It is noticeable that high deposition rate of more than 1150 Å/min could be achieved at 60%. The deposition rate and surface roughness highly correlated with Nh. From the variation of refractive index, deposition mechanisms were inferred. The deposition rate, refractive index, and surface roughness were varied in a range of 1003–1148 Å/min, 1.64–1.96, and 1.37–3.07 nm, respectively.

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