Interactions of argon cluster ion beams with silicon surfaces

Abstract

The formation of irradiation damage for Si(0 0 1) surfaces by Ar cluster ion beams at different acceleration voltages was investigated by utilizing the Rutherford backscattering spectrometry (RBS) measurement. For the peak size of 10 000 atoms per cluster, the Si surfaces had no damage by the irradiation of the cluster ions, when the acceleration voltages were less than 5 kV. Furthermore, for the acceleration voltages larger than 5 kV, the amount of displacement atoms increased with an increase of the acceleration voltage. On the other hand, when the cluster size decreased, the threshold voltage for the damage formation decreased, and it was 2 kV for the peak size of 3000 atoms per cluster. To be compared with the experimental results, molecular dynamic (MD) simulation was used, and it showed that the irradiation of Ar cluster ions with large size and low incident energy did not produce any damage on the Si surfaces. In addition, the Si surfaces, which were previously damaged at a dose of 1 × 10 15 ions/cm 2 by the irradiation of high energy cluster ion beams such as 5 keV ion beams, were re-irradiated at a dose of 1 × 10 16 ions/cm 2 by low energy cluster ion beams such as 2 keV ion beams. The RBS channeling showed that the number of displacement atoms on the damaged surface decreased. The deposited energy on the Si surface was used to improve the crystalline state of the damaged surface, which suggests that the cluster ion irradiation has the ability to anneal the solid surfaces by adjusting the acceleration voltage and the cluster size.