Kazuya Dobashi

Ultrafine Particle Removal Using Gas Cluster Ion Beam Technology

In this paper, the ultrafine particle removal using CO2 gas cluster ion beam (GCIB) technology is investigated. The CO2 GCIB is irradiated the sample at an angle of 0 ° with respect to the surface normal. The higher particle removal efficiency can be achieved at the higher kinetic energy of the gas cluster, and the inside space of line and space pattern particles can be removed. We also suggested that the CO2 GCIB process has the high particle removal uniformity without redeposition of the removed particles. It is possible to remove the ultrafine particle as small as 12 nm in diameter (which is required for 2014 by ITRS 2011). The pattern damage is not observed for 45 nm poly-Si pattern. Moreover, the molecular dynamics simulation is performed to investigate the mechanisms of the particle removal by GCIB irradiation.

Analysis method of metal contamination for the isopropyl alcohol (IPA)

Isopropyl alcohol (IPA) has been commonly used for drying wafers at a final step of cleaning process. As a result, the demand for higher purity IPA has been increasing, and the quality control of metallic impurities in IPA using the reliable analytical method is required. In this study, issues on the analysis of metallic impurities in IPA at ultra-trace level were investigated, and some accurate analysis methods were successfully developed. Furthermore, Fe (iron) impurities in IPA were studied and we indicated that Fe impurities in IPA were smaller than 15 nm and have a positive charge.