High aspect ratio pattern transfer using two-step RIE. The inset shows a high magnification SEM image of 60-nm-wide, 280-nm-high grating lines of 200-nm pitch in which the high aspect ratio (4.7) of the resist stacks is demonstrated. Samples were titled 45° for the cross-section imaging.
Zhang et al. Nanoscale Research Letters 2012 7:380 doi:10.1186/1556-276X-7-380