Integrated approach for low-temperature synthesis of high-quality silicon nitride films in PECVD using RF-UHF hybrid plasmas

Abstract

© 2016 IOP Publishing Ltd. This study investigates low-temperature plasma nitriding of hydrogenated silicon (SiNx:H) film in radio frequency (RF) and RF-ultra-high frequency (UHF) hybrid plasmas. To study the optimized conditions for the deposition of SiNX:H film, this work adopts a systematic plasma diagnostic approach in the nitrogen-silane and nitrogen-silane-ammonia plasmas. This work also evaluates the capability of plasma and radical formation by utilizing different plasma sources in the PECVD process. For the plasma diagnostics, we have purposefully used the combination of optical emission spectroscopy (OES), intensified CCD (ICCD) camera, vacuum ultraviolet absorption spectroscopy (VUVAS), and RF compensated Langmuir probe (LP). Data reveal that there is significant enhancement in the atomic nitrogen radicals, plasma densities, and film properties using the hybrid plasmas. Measurements show that addition of a small amount of NH3can significantly reduce the electron temperature, plasma, and radical density. Also, optical and chemical properties of the deposited films are investigated on the basis of plasma diagnostics. Good quality SiNx:H films, with atomic nitrogen to hydrogen ratio of 4:1, are fabricated. The plasma chemistry of the hybrid plasmas is also discussed for its utility for plasma applications.