A study on the innovative microlens projection lithography applied to the production of microstructures

Microlens projection lithography is a kind of non‐contact projection lithography that uses microlens array components as the projection lenses to produce a large area of microstructural array patterns on photoresisting film. This technology requires partial masking of light on the non‐lens portion of the microlens array, and the conventional approach is through an aligned exposure followed by the plating process that would require accurate positioning equipment, so it is naturally time‐consuming as well as costly in terms of the entire production process. This study applies an innovative technology in the production process that uses a microcircular‐hole array to penetrate a stainless‐steel substrate as the mold, and in collaboration with gas‐assisted thermal pressuring production process that utilizes surface tension of the plastic film to fabricate the hemisphere‐shaped plastic microlens array that is capable of masking light as the projection lens. With such a lens, in collaboration with optic expansion film, Fresnel lens, and millimeter‐grade single‐pattern photomasks, the microlens array projection lithographical optical system is constructed. Using regular millimeter‐grade photomasks, a micrometer‐grade array pattern is successfully fabricated on the photoresist layer through the process of projection exposure and development using such a microlens array projection lithographical optical system. Copyright © 2007 John Wiley & Sons, Ltd.