Research On The Processing Model Of Focused Helium Beam Based On The Monte Carlo Simulation

Focused ion beam(FIB)is a new nano-technology,combining the high-resolution real-time imaging function and nano-fabrication capability,which is widely applied in the semiconduct industry.Compared with traditional liquid metal ion source such as galium ion,helium ion has a lower sputtering yield and higher resolution imaging ability,as a result it can be used for high-precision fabrication of nano-structure.However the incident depth of He ion is greater than that of Ga ion at the same energy condition,resulting in the amorphization damage of crystal material.An accurate simulation can provide researchers with a better understanding of mechanism amorphization damage at micro-scale.In this paper,numerical simulation method is employed to study amorphization damage range and evolution of damage profile with ion dose under different parameters.Experimental results are used for validating the simulation model.The main research work is summarized as follows:1?Based on the theory of interaction between the incident ions and target atoms,the molecular dynamics simulation model of Ga ion implanation and Monte Carlo simulation model of He ion implanation are established.2?The incident range distribution of He ions and distribution of sputtered target atoms under different parameters are analysed by using MC method.The sputtering yield of Ga and He ions is compared and simulation results are used to explain the difference on the atomic scale.3?Damage model is built based on the MC scattering model of He ions.Experiments of amorphization damage in silicon caused by He ions are conducted and the experimental results are used to optimize the simulation model.Simulation results of evolution of damage profile under different enrgy parameter are in good agreement with experimental data,validating the accuracy of simulation model.The mechanism of enegy loss of ions is used to explain the evolution of damage profile.4?The evolution of characteristic variables of damage profile in simulation and experiments are compared.An explanation on the change of the characteristic variables is given based on the simulation results.A new function is adopted to fit the profile curve in polar coordinates.