Development of self-built multilayer aligner for imprint process

Traditional process of thin film transistor-liquid crystal display (TFT-LCD) includes lithography, etching and sputtering. In this paper, a new method combining of a modified ultraviolet (UV)-imprint lithography and self-built multilayer alignment system was developed to replace the traditional TFT-LCD lithography process. Three different kinds of photoresists, including AZ-650 (a positive photoresist from Shipley USA), HOSP (Hygrido Organic Siloxane Polymer) and SE-812 (from ITRI Taiwan), were tested to realize their imprint resolution. Mold release agent, imprint pressure and temperature were found as important parameters of the imprint process. In order to achieve multilayer-imprint ability, an alignment system is essential. Thus a self-built alignment system was developed for the multilayer-imprint process. Two stereo-microscopes were set up to examine angle deviation errors. The resolutions of X-Y-Z and θ axis are 1 μm and 0.5 degree, respectively. Pyrex glass is used to fabricate imprint mold for the experiment. The imprint mold is 500 nm in height and 10 μm in width, respectively. Due to the transparency of the glass mold, the alignment keys can be observed clearly and aligned easily by using the stereo-microscopes. The experimental result shows that the accuracy of this alignment system can achieve 1 μm.