Laser interference lithography using spray/spin photoresist development method for consistent periodic nanostructures

Generally, a simple immersion method for development of photoresist (PR) has been used to fabricate nanostructures by interference lithography (IL). However, the immersion method has the disadvantage that fabrication is inconsistent, especially for large-area periodic structures. Herein, we introduce the spray/spin PR development (SSPRD) method to fabricate periodic nanostructures using IL. By quantitative analysis and comparison, we characterized the effectiveness of the SSPRD method to develop PR. In our experiments the SSPRD method produced reliable uniform nanostructures, whereas the immersion method showed very poor consistency. In the SSPRD, rotation speed was very important: if it was too low the development speed differed between edges and center; if the rotation speed was too high it caused a distortion of nanostructures by unstable local flow induced by spraying and rotation So, to reduce this distortion, we adopted the puddle developing process; as a result the uniformity and repeatability of developed nanostructures were improved. These results demonstrate that the SSPRD method can be useful for fabrication of consistent periodic nanostructures.