Change of Film Properties of RPALD Titanium Oxide by Applying Positive DC-Bias

Abstract

As semiconductor devices are gradually miniaturized, the difficulty of reducing the lithography light source is more increasing. Therefore, the importance of multi-patterning technology is gradually increasing. As a multi-patterning spacer, deposition of TiO2 films via DC-bias remote plasma atomic layer deposition was investigated. The optical emission spectroscopy diagnosis showed that the oxygen radical intensity was increased by applying positive DC-bias. In X-ray photoelectron spectroscopy analysis, the oxygen vacancy was calculated at 18.51% in the As-dep film but decreased to 12.31% in the DC-bias film. When plasma treatment was applied to the As-dep film, oxygen vacancy was reduced to 12.35%. Furthermore, when plasma treatment conducted with DC-bias, oxygen vacancy was 10.11%, which was further lower than the 12.35%. The X-ray reflectivity analysis showed that As-dep film had a density of 3.82 g/cm3, which increased to 3.90 g/cm3 by DC-bias. In the case of plasma treatment, compared to As-dep film, the density increased regardless of DC-bias, although there was no significant difference according to DC-bias. For wet etch rate (WER), the As-dep thin film showed the highest value of 4.54 Å/s and decreased to 2.26 Å/s by applying DC-bias. Plasma treatment films showed WER of 3.97 Å/s and 3.07 Å/s, respectively, with or without DC-bias. Atomic force microscope analysis shows decreased roughness as DC-bias is applied. According to transmission electron microscopy results, side step coverage was improved from 95% to 99% by DC-bias.