Aperture-Controlled Fabrication of All-Dielectric Structural Color Pixels

While interference colors have been known for a longtime, conventionalcolor filters have large spatial dimensions and cannot be used tocreate compact pixelized color pictures. Here we report a simple yetelegant interference-based method of creating microscopic structuralcolor pixels using a single-mask process using standard UV photolithographyon an all-dielectric substrate. The technology makes use of the variedaperture-controlled physical deposition rate of low-temperature silicondioxide inside a hollow cavity to create a thin-film stack with thecontrolled bottom layer thickness. The stack defines which wavelengthsof the reflected light interfere constructively, and thus the cavitiesact as micrometer-scale pixels of a predefined color. Combinationsof such pixels produce vibrant colorful pictures visible to the nakedeye. Being fully CMOS-compatible, wafer-scale, and not requiring costlyelectron-beam lithography, such a method paves the way toward largescale applications of structural colors in commercial products.