High quality SiO2 film by radical improved DC bias Plasma enhanced Atomic layer deposition using BDEAS and CO2 p

Abstract

SiO2 is being used in various parts of semiconductor industries such as gate dielectric, gate spacer and double patterning. SiO2 film was deposit by radical enhanced RPALD, which has DC bias applied to remote RF plasma region. BDEAS precursor and CO2 plasma were used for SiO2 thin film deposition. DC bias power condition was changed from 0W to 500W. OES was used to identify plasma density difference by looking the intensity difference with DC bias. The GPC result according to DC bias confirmed that the GPC increased to 1.225Å/cyc at DC bias power 500W. XRR and WER was measured to confirm the density of SiO2 film by DC bias. We found that film densities increased when DC bias was applied. Density was increased from 2.18g/cm3 at 0W to 2.35g/cm3 at 500W. This is due to the increase in O radical within plasma when DC bias is applied to plasma, resulting in a more dense film deposition. The chemical bonding of the film was measured through XPS and FT-IR. For XPS, the Si-O4 peak region in the electron orbital spectra of Si 2p increases to about 92.2% when DC power reaches 500W. FT-IR result also shows that absorbance of Si-O bonding increases as DC power increase. Breakdown voltage of SiO2 film was enhanced when DC bias was applied to the plasma. In the case of breakdown voltage, 8MV/cm was shown at DC bias 0W and 3MV/cm was increased from DC bias 500W to 11MV/cm. Through this study, we looked at effect of DC bias during SiO2 deposition when DC bias is applied to plasma region. If DC bias is applied during RF plasma, high quality SiO2 film can be obtained even in low temperature as DC bias activates radical and ion leading to plasma density enhancement.