The removal of intentionally contaminated Cu impurities on Si substrate using remote H-plasma treatments

The removal of Cu impurities on Si substrate was investigated by using remote H-plasma treatments. This work focussed on eliminating Cu impurities on Si substrate which was intentionally contaminated by dipping it into 1 ppm CuCl2 chemical standard solution. Remote H-plasma treatments were conducted to remove Cu impurities and depended on the plasma exposure times and distances. After the remote H-plasma treatments, Si surfaces were analyzed by TXRF (total reflection X-ray fluorescence) and AFM (atomic force microscope). The Cu concentration was reduced more than a factor of 10-100 and its surface roughness improved significantly after the remote H-plasma treatments. CU2+ ions can be reduced in the form of Cu element and formed as the compound (Cu(OH)(2)) and the chemical oxides (SiO and SiO2) on the Si substrate. Under the condition of remote H-plasma, the removal mechanism of Cu impurities is studied and understood by applying the formation mechanism of volatile by-products such as CuHx*, CuO*, SiO* and H2O*, and the lift-off phenomena during the removal of underlying oxides such as SiO and SiO2.