Comparison of MIBK/IPA and water/IPA as PMMA developers for electron beam nanolithography

In electron beam lithography, resist behavior, such as sensitivity, contrast, exposure dose latitude, roughness and resolution, are influenced by the nature of the resist, the developer type and composition, and the development technique. In earlier work, ultrasonically assisted development was used to improve resolution and line edge roughness. Here we investigate the influence on resist behavior of an unconventional developer consisting of IPA and water. We observe improvements in sensitivity (∼40%), in contrast (∼20%), in exposure dose latitude (∼40%) and in roughness (nearly an order of magnitude) compared to the use of a conventional 1:3 MIBK/IPA developer. These improvements assisted in the fabrication of gratings of minimum size 16 nm equal line spacing in PMMA resist with 3:7 water/IPA developer.