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We tested 2-methyl-2-adamantylmethacrylate-mevalonic lactone methacrylate (2MAdMA-MLMA) resist on thick films and found that the pattern collapse determined the resist performance in high aspect ratio patterning. To solve this problem, we investigate the effects of modifying the softbake-PEB (post exposure bake) condition, the developer, and the photo acid generator (PAG). We replaced the 2.38% (0.27N) TMAH developer with a 0.27N TBAH (tetrabutylammonium hydroxide) developer, which functioned as a surfactant, and the collapse was reduced markedly for thicker films. As a result, the exposure and focus latitudes improved. These results suggest that good solubility in an exposed region reduces the collapse, allowing high aspect ratio patterning to be achieved.
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