Removal of Cr and Zn Impurities from the Si Substrate using the Remote H_2 Plasma

摘要

The removal of Cr and Zn impurities on Si substrates using the remote H_2 plasma was investigated. To determine the optimum process condition, the remote H_2 plasma cleaning was conducted for various rf-powers and plasma exposure time. The optimum process parameters for Cr and Zn removal were set at the rf-power of 20W and plasma exposure of 5 min. The concentrations of Cr and Zn impurities were reduced by more than a factor of 2 and the minority carrier lifetime increased alter the remote plasma H_2 cleaning. Also RMS roughness decreased by more than 30 percent approx 50 percent after the remote H_2 plasma cleaning. AFM analysis results also show that the remote H_2 plasma cleaning makes no damage to the Si surface. The removal mechanism of the Cr and Zn impurities in the remote H_2 plasma cleaning is proposed to be the lift-off mechanism during the removal of the underlying chemical oxides.