A simple and cost-effective method of patterning photonic crystal (PhC) or similar structures by electron beam lithography is demonstrated. Instead of using fine resolution and a multitude of small-sized beam spots to write a single hole, the combination of a single electron-beam spot having the size of the hole and a position resolution equal to the period of the PhC is used. This single-spot exposure scheme typically shows an order-of-magnitude reduction in the required job time compared to that for the conventional multi-spot exposure scheme. In addition, the inherently circular shape of the electron-beam spot is directly transferred into the UV3 resist used in this work, leaving uniform circular holes after development. A cross-sectional view of the holes shows a very good verticality in the sidewalls of the resist. A modified scheme using four spots is also demonstrated which alleviates some limitations encountered in the single-spot exposure scheme.
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