Wall profile of thick photoresist generated via contact printing

High-aspect-ratio patterns generated by direct contact or proximity printing in LIGA and other similar processes have recently gained great interest in the field of MEMS. One key issue for a successful thick-film lithography Is the control of wall profile. This paper deals with this issue based on an approximation including the effects of Fresnel diffraction and exposure kinetics for various types of photoresist. This approach leads to simple but practical formulas for estimating the wall profile and resolution for the near-field lithography of thick photoresist.