Variable proximity multiple exposures in SR Lithography for fabrication of 3D micro/nanostructures

The variable proximity multi exposure technique in SR lithography is introduced. This technique provides to fabricate micro/nano gratings include Sub-wavelength gratings. The sub-wavelength gratings for antireflection were fabricated using this technique. Fresnel and Fraunhofer intensity distribution simulation for estimate the properly gap were performed. The simulation was done by the slit width of 150 nm and 250 nm, and the proximity gap was from 0 up to 100 mum. On the other hand, evaluation of proximity gap effect with conventional exposure was performed. We found the appropriate value of the gap for obtaining high contrast, and the gap for provide a taper. The experiment results were in agreement with the calculated result. T Then the multiple exposure with appropriate gap were performed and we were able to obtain the three dimensional sub-wavelength structures.