Radical-Induced Effect on PEALD SiO2 Films by Applying Positive DC Bias

Abstract

Multiple patterning technology has become an essential process. In the commonly used self-aligned multiple patterning process, the spacer should be dense at low temperatures and have a high elastic modulus. To meet these conditions, many thin-film deposition methods, such as plasma-enhanced atomic layer deposition, have been studied. We investigated remote plasma atomic layer deposition (RPALD) technology with a DC positive bias. After applying bias voltage to the plasma region, changes in the plasma properties, such as density and flux, were examined and applied to SiO2 deposition. When DC positive bias was applied, the sheath voltage decreased, causing an increase in the radical density, which contributed to the surface reaction. In an elastic recoil detection analysis, the application of 200 V reduced the hydrogen content of the film from 11.89% to 10.07% compared with no bias; an increase in SiO2 film density from 2.32 to 2.35 g cm(-3) was also measured. The elastic modulus and hardness were shown to increase through a nano-indenter analysis and surface roughness improved with the suppression of energetic ions impinging on the film surface. Thus, the application of DC positive bias during the RPALD process effectively improved the physical, chemical, and mechanical properties of SiO2 film.