Estimation of Final Shape and Accuracy of the Electron Beam Drawing Process

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The electron beam direct writing lithography has become one of the most promising technologies for reliably fabricating fine mask patterns in the order of submicron which may be beyond the practical resolution limit of optical lithography. This study aims to estimate and evaluate geometrical shape and accuracy of the mask patterns onthe electron beam drawing process.Firstly, the effects of the drawing conditions as acceleration voltage, beam current, and scanning rate were investigated and the accuracy of the mask patterns was evaluated by a differential interference microscope, a scanning electron microscope (SEM) and so on. It is made clear through the experiments and the numerical simulation that the shape and the accuracy of the mask patterns are influenced by the diameter of the electron beam which depends especially on the acceleration voltage.Secondly, anisotropic etching which is relatively easy process to fabricate the micro-mechanical parts was used in order to clarify the effect of the accuracy of the mask patterns on the surface integrity of the etched single crystal silicon. It is found from the experimental results that the miss-alignment of the mask pattern should be less than 0.7 degree. Also, a formula that compensates the side etching was proposed and the accurate machining became possible.