Transmission optical micrographs of patterned tiles with varied sizes D from left to right (along x axis; 331 nm ≤ D ≤ 500 nm) and thickness h (along y axis) of dielectric layer before (a) and after (b) top-layer Ag deposition. Each tile (20 μm) consisted of 40 square-shaped pixels (P = 500 nm). (c) Schematics showing 16 pixels to provide intuitive concept of filling factor discussed below. (d) The thickness variation of spacer layer as a function of exposure dose corresponding to the red-color highlighted column in (b). (e) Checkerboard patterns with decreasing pixel size. Scale bars: 50 μm (a, b), 5 μm (e(i-iv)), and 2.5 μm (e(v)).