Maskless beam pen lithography based on integrated microlens array and spatial-filter array

A beam pen lithography system is proposed for ultraviolet (UV) patterning of complicated patterns in a maskless manner. The system consists of a single UV light-emitting diode (LED), a double-sided microlens/spatial-filter array (MLSFA), and a motorized x-y stage. The double-sided MLSFA contains a pinhole array sandwiched by two microlens arrays. The microlens arrays are fabricated by an excimer laser micromachining system to achieve accurate and optimized lens profiles obtained from optical simulation. Techniques have been developed in the fabrication processes to guarantee good alignment between the pinhole array and the two microlens arrays. Finally, arrayed UV spots are formed with feature size around 4 to 5 μm. Through mechanical movement of stage and intensity control on the UV LED, a number of complicated patterns are experimentally demonstrated using this type of beam pen lithography. It offers a simple, inexpensive, and portable choice on maskless UV patterning with great potential for future applications.