Simulation Of The Proximity Effect Of Electron Beam Lithography

Electron beam lithography is considered as the best technique to offer the higher patterning resolution. It has many advantages, such as short wavelength, easily to be controlled, high precision and flexible, etc. But the proximity effect is the most important limitation of the sensitivity of lithography. It is so important and necessary to investigate the reason of the proximity effect by computer simulation.A suitable model for Monte Carlo simulation of electron beam lithography process and the corresponding program have been analyzed and developed, which is the main work of the paper. The complex scattering processes of Gauss-distribution electron beam in resist-substrate were simulated and the energy dissipation density distributions were calculated. The developed-resist profiles were simulated combining the energy dissipation density distribution and the development model. The main achievements can be summed up as follows:1. Electron beam lithography has high sensitivity since it is free from limitation from diffraction effect. It will be the most common technique of the next generation lithography to replace the conventional optical lithography. The proximity effect is the most important limitation of the sensitivity of lithography. The computer simulation of the proximity effect has been investigated systematically in this paper. The influence on proximity effect of the energy of electron beam, the material of substrate and the depth of resist has been simulated and analyzed. The simulation results are compared with the experimental data and are found to fit well. It is found that, higher energy of the electron beam, thinner resist and smaller atomic number will cause smaller proximity effect independently.2. The developed profiles of the gratings were given by the computer simulation before and after pattern correction of the layout. And then the simulation results were compared with the experimental results. It was proved that the results of the simulation can be used to guide the experiment.3. The production mechanism of proximity effect and effective approaches of proximity effect correction were investigated. Proximity effect is unavoidable. But it can be compensated through exposure dose modulation or shape-dimension adjustment technique or both of them. Also it can be reduced through process measures. The experimental results show that proximity effect is influenced by exposure and development conditions.