High efficiency color filter process to improve color balance in semiconductor array imaging devices

Abstract

Formation of integrated color filters for gain-ratio balanced semiconductor array imagers using a spectrophotometric feedback control loop to adjust layer thickness during the deposition process is disclosed. The fabrication sequence of G/R/B conventionally used in Prior Art has been changed to B/R/G or B/G/R to enable the process to adapt to yielding specified color gain-ratio values without the need for integrated circuit redesign. A high efficiency color filter process is demonstrated wherein the additional neutral-density attenuator layers and/or spacer layers required in Prior Art fabrication methods are eliminated. The disclosed process is shown to enable high-precision thickness control of the color filter layers. Blue coating lift-off problems and the steric effect associated with successive depositions of color layers having step-height variations are eliminated. Statistical process control (SPC) is optimized by calibration of the color balance gain-ratio using the product photodiode arrays and amplifier integrated circuits with a real-time spectrophotometric feedback control-loop during the dye or pigment layer deposition process.