The effect of deposition pressure on the surface roughness scaling of microcrystalline silicon films by very high frequency plasma-enhanced chemical vapor deposition

Abstract

The scaling behaviour of surface roughness evolution of μc-Si:H prepared by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) has been investigated using spectroscopic ellipsometry (SE). The growth exponent β was compared for the film deposited under the different pressure P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> . For films deposited at P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> = 70 Pa, the growth exponent β is about.0.22, which corresponds to the definite diffusion growth. However, films deposited at P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> = 300 Pa show abnormal scaling behavior with the exponent β of about.0.81, which is much larger than 0.5 of zero diffusion limit in the scaling theory. This implies that some roughening increasing mechanism such as shadowing effect contributes to the growing surface.