Fabrication of nano metallic holes for color filters based on a controllable self-assembly of polystyrene spheres

• An effective metal nano-hole fabrication method was employed to fabricate color filter structured by metal nano-holes.
• Precise holes size can be obtained by accurately controlling the PSs etching process.
• Precise holes period also can be obtained by selecting the appropriate PS diameter.
• Color filters with different structure parameters were obtained.
• The influences of structure parameters on the transmitted spectrum were analized.

Color filter structured based on metallic nano-holes arrays is attractive for better monochromaticity and higher transmission than conventional band-pass filters. An efficient method that combines colloidal polystyrenes spheres (PSs) self-assembly, reactive ion etching (RIE), metal deposition and lift-off process was employed to fabricate the color filter in this paper. The designed hole period is realized by selecting PSs with appropriate diameter. PSs can be controllably reduced in diameter and separated from each other by RIE-assisted etching technology according to the required holes array. Then, a metal layer is deposited onto the samples and followed by a lift-off process. Using this method, metallic holes arrays with feature sizes ranging from 150 nm to 450 nm and periods ranging from 300 nm to 500 nm were fabricated. The transmittance spectra of the holes arrays are measured and analyzed. Three kinds of color filters have been obtained with passed wavelengths of 605.6 nm, 682.41 nm and 810.2 nm respectively.

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