Precise Simulation On Low Energy Ion Implantation With Molecular Dynamic Approach

With the scaling down of device size, low energy ion implantation technology, which is required for ultra-shallow junction, has emerged to be a research hotspot at the present. It is a difficult task to implement very low energy ion implantation, and the same situation exists in the computer simulation on it. Generally speaking, an excellent simulation tool can make the experiments smoother and greatly reduce the experimental cost, so this paper just focuses on this area to develop a good low energy ion implantation simulator.Comparing with high-energy ion implantation, low energy ion implantation brings more problems. When incident energy appears to be comparable with interaction energy between target atoms, we have to take simultaneous interactions among atoms into account to obtain accurate simulation results. Under this situation, traditional BCA methods become inapplicable and then we will resort to more reasonable MD methods. However, full MD method is still not practical due to its very low computing efficiency. Therefore, based on the fundamental physical consideration in full MD methods, we introduce recoil interaction approximation into our program. Recoil interaction approximation does not bring too large errors, but greatly improves the computing efficiency. In order to obtain higher simulation accuracy and make our program run faster, we also introduce rare-event algorithm. With the introduction of many reasonable physical approximations and speedup algorithms, our low energy ion implantation simulator LEACS not only can obtain good simulation results, but also proves to be applicable under the current computing capacity.Using our program, we implement a gTeat number of ion implantation simulations and compare our results with the SIMS data supported by Fujitsu Corporation. The simulated range profiles agree very well with SIMS data.