Fig. 2. Top-view (scale bar: 10 μm) and cross-sectional (scale bar: 5 μm) HR-SEM images of sub-μm PR column arrays with different pitches of (a) 3 μm, (b) 5 μm, and (c) 10 μm, fabricated on top of PR1. The black spots and the white rings in the top-view images indicate the flat-top and the sidewall slope of the PR columns, respectively. The close-up image (scale bar: 1 μm) in (a) shows the shape of a fabricated PR column, which has a sub-μm flat-top indicated by a red circle, and a sloped sidewall profile.
