Dynamics of lattice damage accumulation for MeV ions in silicon

Abstract

Although the domination of electronic stopping over nuclear stopping may be regarded as an important practical advantage for high energy (MeV) ion processing, exact knowledge of the doping introduced into the active regions as well as of the process-associated defects and their thermal stability is essential for an understanding of device performance. In the present work we review the results of our recent investigations on lattice damage accumulation in single crystal Si resulting from high energy ion implantation in the implantation temperature ( T i ) range between liquid nitrogen temperature and 200 °C. The ion species used were 1 MeV O +, 1.25 MeV Si + and4.8 MeV Er + (0.2 < M 2/ M 1 < 1.7). Ion implantation was carried out using virgin Si as well as Si containing pre-existing damage. The lattice damage was studied using Rutherford backscattering/channeling spectrometry (RBS) and cross-sectional transmission electron microscopy (XTEM). The experimental results are correlated with the predictions of the model of Hecking and Te Kaat [Appl. Surf. Sci. 43 (1989) 87]. The temperature dependence of the damage accumulation in the virgin Si suggests that the annihilation of simple defects via intracascade and intercascade recombination processes is controlled mainly by the temperature, while the nucleation of defect clusters during implantation appears to be influenced by spatial proximity effects related to the deposited energy density. Finally, the dynamics of damage accumulation is shown to be strongly influenced by the pre-existing damage structure.