To overcome the alignment error caused by the overlay when the conventional electron beam lithography produces the four-step relief structure, the paper did a detailed research on the influence of different accelerating voltage on the exposure depth during the process of exposure. Therefore, it drew out the limit value of exposure depth under different accelerating voltage and the relationship between the electron beam energy and critical exposed dose. Through the analysis of the experimental results, it worked out the optimum process parameter combination of exposure. The accelerating voltage of the first exposure was 5keV and the exposed dose was 100μC/cm2, while the second accelerating voltage was 15keV and the exposed dose was 150μC/cm2. Finally, the four-step relief structure was made on the resist layer and this structure met the needs of the graphic transfer process on the etch mask.
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