Imec presents a new method for faithful color separation with submicron resolution using standard back-end-of-line processing on 300mm wafers. The technology will improve the performance of high-end cameras by delivering a higher signal-to-noise ratio, better color quality and unprecedented spatial resolution. To achieve this, an array of vertical Si3N4 multimode waveguides in a SiO2 matrix was realized. The waveguides have a tapered, diffraction-limited entrance to collect the incoming light. In each waveguide, the incident photons excite both symmetrical and asymmetrical modes that propagate differently through the waveguide, resulting in a unique “beating pattern” between the two modes for a given frequency. This pattern allows for spatial separation at the end of the waveguides that corresponds to a specific color. The total yield of light from each waveguide is estimated to be over 90% within the range of human color perception (wavelength range 400-700nm), making it superior to color filters.
