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

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 20,000 atoms/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 5 keV show that the damage decreases very quickly, from 7.9 nm to 0.3 nm with increasing the cluster size from 500 to 5000 atoms/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. (c) 2005 Elsevier B.V. All rights reserved.