Microfabrication of a color filter array utilizing colored SU-8 photoresists.

Patterned color filter arrays are important components in digital cameras, camcorders, scanners, and multispectral detection and imaging instruments. In addition to the rapid and continuous progress to improve camera resolution and the efficiency of imaging sensors, research into the design of color filter arrays is important to extend the imaging capability beyond conventional applications. This paper reports the use of colored SU-8 photoresists as a material to fabricate color filter arrays. Optical properties, fabrication parameters, and pattern spatial resolution are systematically studied for five color photoresists: violet, blue, green, yellow, and red. An end-to-end fabrication process is developed to realize a five-color filter array designed for a wide angle multiband artificial compound eye camera system for pentachromatic and polarization imaging. Colored SU-8 photoresists present notable advantages, including patternability, color tunability, low-temperature compatibility, and process simplicity. The results regarding the optical properties and the fabrication process for a colored SU-8 photoresist provide significant insight into its usage as an optical material to investigate nonconventional color filter designs.