Influence of electron scattering on resist pattern edge roughness in low dose electron beam lithography

Electron beam lithography simulation is presented. A line pattern edge roughness of a resist after development process is discussed based on simulations of electron scattering in the resist film and the resist development process. Fixed threshold energy model is applied for the simulation and variations of a line width and the line edge roughness are obtained as functions of the incident electron energy, resist thickness and electron doses. The minimum line edge roughness is obtained, when the dose is more than that can be produced just the designed width of lines. As the dose increases more than that to obtain the minimum edge roughness, the roughness increases with increasing the dose. On the contrary, the roughness decreases with the dose as the statistical nature at very large doses as 100μC/cm 2. Variable threshold energy model is applied and a dose variation of the line edge roughness is obtained. The LER is just reproduced by the statistical fluctuation, and it shows a linear relationship with 1/√dose Although the results obtained by present analyses agree qualitatively with experiments, the edge roughness obtained by experiment shows much smaller than the results, and some other mechanisms should be taken into account for the quantitative agreement.