Line Edge Roughness of Developed Resist with Low-Dose Electron Beam Exposure

Abstract

Line edge roughness of a developed resist pattern is calculated in the case of low accelerating voltage electron beam lithography. Based on the diffusion equation, the Gaussian distributions of the acid distribution after post-exposure baking in a chemically amplified resist are shown for various conditions, if acid is generated from a point source. It might be considered reasonable to relate the acid broadening to the broadening of the deposited energy, which is originally introduced by the electron beam in the resist. In the present simulation, the energy deposited by the primary electron beam is convoluted with the Gaussian distribution, and the resulting edge roughness variation of the 100-nm-wide line pattern after development is discussed. Because of the convolution, the roughness decreases with increasing diffusion length of the distribution in general, and the dependences of the roughness on the exposure dose, thickness of the resist and the accelerating voltage of the primary beam are discussed.