Cross-sectional micrographs of SML exposed at 30 keV and developed in MIBK/IPA (1:3) for 20 s. The panels show (a) 5-μm array of 200-nm-pitch gratings in 300-nm-thick resist, (b) magnified image with thickness of 282 nm and line widths of 45 to 67 nm from top to bottom of gratings, and (c) 400-nm-pitch gratings in >1,500-nm-thick resist (no clearance) with the achieved depth of 1,380 nm and line widths of 180 to 220 nm from top to bottom of gratings. The exposure doses were (a, b) 3.6 nC/cm and (c) 700 μC/cm2, and the aspect ratios ranged from (a, b) 4.2 to 6.3 and (c) 6.3 to 7.7. The resist was cleaved and coated with a 6-nm Cr layer before imaging.
Mohammad et al. Nanoscale Research Letters 2013 8:139 doi:10.1186/1556-276X-8-139