Abstract:The SU-8 thick photoresist lithography process is widely used in the preparation of high aspect ratio structures, but during the photoresist stripping process, it is prone to thickness fluctuations at different positions on the wafer and between wafers, resulting in local overexposure or underexposure and reducing transfer accuracy. This article studied the effects of photoresist thickness and exposure dose on photolithography under different pre baking times using the Taguchi method. It was found that increasing the prebake time could effectively suppress the fluctuation of line width. When the prebake time was increased from 90 min to 110 min, the stability of line width increased by 86.8%; And the mechanism was explained through simulation analysis: the extension of prebake time can suppress the production of photoacid at the bottom of SU-8, increasing the concentration difference of photoacid along the thickness direction, resulting in a decrease in photoacid diffusion to the unexposed areas on both sides during post baking, thereby suppressing the line width variation caused by the mismatch between adhesive thickness and dose, providing a solution and theoretical basis for solving the error caused by the fluctuation of adhesive thickness.
