High aspect ratio features in poly(methylglutarimide) using electron beam lithography and solvent developers

The properties of poly(methylglutarimide) (PMGI) when used as an electron beam resist are investigated. The results show that PMGI, when developed with a weak developer, xylenes, shows contrast higher than 12, which is comparable to the contrast achieved in cold developed poly(methylmethacrylate), and approximately twice as high as the recently achieved PMGI contrast using other developers. Using this high contrast polymer, sub 20 nm features with aspect ratios greater than 30:1 can be readily achieved. In addition to the superior positive tone behavior, this polymer behaves as a negative tone resist at higher exposure doses. Negative resist features as small as 20 nm can be fabricated when methyl isobutyl ketone is used to develop negative tone PMGI.