Irradiation of silicon surface by Ar cluster ion beam: Cluster size effects

Abstract

The influence of cluster size on damage layer thickness produced by Ar gas cluster ion beam (GCIB) irradiation is presented. The GCIB has a wide cluster size distribution which has been difficult to control. To obtain a narrow size distribution of the GCIB, the mass filter containing a strong permanent magnet is developed. In this study, the size-selected Ar-GCIB irradiates the Si substrates. The cluster size is varied between 500 and 20,000atoms/cluster. After irradiation, the damage layer thickness on Si substrates is measured by ellipsometry. The results of size-selected Ar-GCIB irradiation on Si substrates at acceleration energy of 5keV show that the damage decreases very quickly, from 7.9nm to 0.3nm with increasing the cluster size from 500 to 5000atoms/cluster. This tendency is in agreement with the results calculated by molecular dynamics simulation. These results suggest that the GCIB process is promising for low damage processing of semiconductor material.