Excellent conformality of atmospheric-pressure plasma-enhanced spatial atomic layer deposition with subsecond plasma exposure times

Abstract

Atmospheric-pressure spatial atomic layer deposition (s-ALD) has emerged as a scalable deposition technique combining the advantages of ALD with high deposition rates, suitable for low-cost and high-volume applications. There is a growing interest in atmospheric-pressure plasma-enhanced spatial ALD (PE-s-ALD), e.g., to allow for deposition at reduced temperatures or for materials that are otherwise difficult to prepare by thermal ALD. For low-pressure PE-ALD, conformal films on high aspect ratio features have been achieved despite plasma radical recombination, and the aspects influencing conformality are fairly well understood. This work addresses surface recombination and conformality for atmospheric-pressure PE-s-ALD films. We demonstrate that conformality can be achieved for SiO2 and TiO2 films deposited by atmospheric-pressure PE-s-ALD inside high-aspect-ratio trenches with short plasma exposure times. Using plasma exposure of 0.73 s results in conformal SiO2 and TiO2 films in structures with aspect ratios of 74 and 219, respectively. Additionally, the recombination probabilities of oxygen radicals at atmospheric pressure are extracted to be 4×10−4 for SiO2 and 6×10−5 for TiO2. These results demonstrate that atmospheric-pressure PE-s-ALD can be used for conformal and high-speed depositions on 3D substrates.