Removal of Fe impurities on the Si substrate using remote hydrogen plasma

Effects of remote hydrogen plasma cleaning process parameters on the removal of Fe impurities on Si surfaces were investigated. Fe removal efficiency is enhanced with decreasing the plasma exposure time and increasing the rf-power. The optimum plasma exposure time, rf-power and substrate temperature are 1 min, 100 W, and 300°C respectively, in the range below 10 min and 100 W. According to the AFM analysis results Si surface roughness was improved by 30% or higher, which seems to be due to the removal of particles by plasma cleaning. The Fe impurities on the Si surface are considered to be contaminated as physisorption or incorporation of Fe-compounds on/in the chemical oxides, which can be explained from the thermodynamic point of view. The removal mechanisms of the Fe impurities are thought to be formation and evaporation of volatile compounds and lift-off of the Fe impurities during the removal of the underlying chemical oxide layer during the remote hydrogen plasma treatment.