Microlens arrays with integrated pores as a multipattern photomask

Photolithographic masks are key components in the fabrication process of patterned substrates for various applications. Different patterns generally require different photomasks, whose total cost is high for the multilevel fabrication of three-dimensional microstructures. We developed a photomask that combines two imaging elements-microlens arrays and clear windows-in one structure. Such structures can be produced using multibeam interference lithography. We demonstrate their application as multipattern photomasks; that is, by using the same photomask and simply adjusting (i) the illumination dose, (ii) the distance between the mask and the photoresist film, and (iii) the tone of photoresist, we are able to create a variety of different microscale patterns with controlled sizes, geometries, and symmetries that originate from the lenses, clear windows, or their combination. The experimental results agree well with the light field calculations. (c) 2005 American Institute of Physics.