Improving the accuracy of ion implantation simulations through the use of DFT-MD methodology

Ion implantation is a crucial process in the fabrication of semiconductor devices, but accurately predicting the impurities distribution in the low energy range is still challenging. The widely used method to simulate this process is molecular dynamics with recoil interaction approximation (RIA-MD), which uses the translational method to replace traditional periodic boundary conditions. However, this approach leads to accuracy loss due to the simplification of atom-atom interactions and bulk crystal properties. Our study presents a method to simulate the impurity distribution after ion implantation at low energy, which combines all-electron density-functional theory (DFT) and full molecular dynamics (MD). Unlike the RIA-MD method, DFT-MD method calculates the movements of all energetic ions and simulates the whole bulk crystal properties. Thus, it provides a more realistic representation of atom-atom interactions. We used not only the experimental values reported by references but also the experimental value measured by actual ion implantation technology samples. This enabled us to make a more accurate comparison between the DFT-MD and RIA-MD methods. Specifically, the dopant profiles and amorphous thickness obtained using the DFT-MD method were found to be in good agreement with experimental data. These findings demonstrate the effectiveness of our method and highlight its potential to advance the field of ion implantation simulation. Moreover, our method has the potential to be useful in developing atomic-scale technology computer-aided design (TCAD) tools, as well as in other fields of research that require accurate ion implantation simulations.