Color-filter arrays for silicon solid-state image arrays sensors

Abstract

A monolithic fabrication process for color-filter arrays was developed. The color-filter arrays were composed of a blue, green, and red colored mosaic of transparent film elements. The color-filter arrays were fabricated on silicon wafers on which linear arrays of silicon photodiodes had previously been fabricated. Different colored film elements overlaid different photodiodes so that the spectral response of any photodiode was the produce of its intrinsic response and the transmittance characteristic of the color filter. This technology is applicable to the development of color image sensor arrays. The color-filter arrays utilized a transparent, organic polymer film base as a support for dyes. Organic solvent dyes were chosen to impart color into the film material. Solvent spin-casting techniques were used to coat silicon wafers with polymer films of different colors. The polymer films were patterned by selectively etching the films in an oxygen plasma through an aluminum mask. Measurements were performed on the color-filter-covered photodiodes to determine their spectral response as a function of the wavelength of the incident light. The measurements showed that the color-filter arrays had good color spectral characteristics.