Color filter incorporating a subwavelength patterned grating in poly silicon

Abstract

A color filter based on a subwavelength patterned grating in poly silicon was proposed and realized on a quartz substrate. It was produced by utilizing the laser interference lithography technique to feature wide effective area compared to the costly e-beam lithography. An oxide layer was introduced on top of the silicon grating layer as a mask to facilitate the silicon-etching and to enhance the filtering selectivity as well. The structural parameters for the device include the grating pitch and height of 450 nm and 100 nm respectively, the silicon stripe width of 150 nm, and the oxide thickness of 200 nm. The fabricated device offered a spectral response suitable for a blue color filter, exhibiting the center wavelength of approximately 460 nm, the bandwidth approximately 90 nm and the peak transmission 40%. The positional dependence of its performance was examined to find the effective area of 3 x 3 mm(2), where the variation in the relative transmission efficiency and in the center wavelength was less than 10% and 2 nm respectively. Finally, the influence of the angle of the incident beam upon the transfer characteristics of the device was investigated to reveal that the rate of change in the relative transmission was equivalent to about 1.5%/degree.

Color Filter Utilizing a Thin Film Etalon

“…이 필터는 주로 스핀 코팅된 유기박막 형태로 상용화 되었으나, 최근에는 공정 단 순화 등을 목적으로 전자빔 및 레이저 간섭 리소그래피 (lithography) 방법에 의해 형성된 광파장 이하의 실리콘 및 금속 격자 구조가 시도되어 왔다 [4][5][6] . 하지만 이 경우에 편광 의존성과 고가의 장비가 수반되는 공정 등의 문제점을 지니 고 있다.…”

Scattering light from several-ten nanometer defects of an optical diffractive element

“…Optical elements with subwavelength structures, including diffraction gratings [1], color filters [2] and image sensors [3], are commercially produced under highly-developed nanofabrication technology. In fabrication of these subwavelength optical elements, to suppress scattering light is essential to improve the performance of products that mounted them.…”

Color effects from scattering on random surface structures in dielectrics

“…Such devices have been proposed that are based on either sub-wavelength one dimensional gratings [4][5][6][7] or nano-holes in metal surfaces that rely on plasmon enhanced propagation [8,9]. These filters are all multi-material devices, and require several process steps to fabricate.…”

“…The structures show color effects in the direct transmission of white light, when fabricated in an otherwise fully transparent and colorless material and the textured surfaces thereby work as structural color filters fabricated in a single material. The optical performance of the demonstrated color filters rely on mechanisms different from those of periodic color filters [4][5][6][7][8][9], which in general have higher efficiencies and smaller spectral widths. On the other hand, the type of filter proposed here will benefit from a much lower fabrication cost.…”