High aspect ratio nanostructure for anti-refection function in CMOS image sensor devices

Cover glass on the CMOS image sensor chip plays a critical role in image quality. To improve cover glass optical properties, the double sided nanostructure was introduced onto cover glass surfaces as an anti-reflection means in this work. By DUV photolithography and etching process, such nanostructure with high aspect ratio patterning enhanced transmittance to 98~99% and had better angular response than the double sided multi-film anti-reflection coating. In addition, the petal flare phenomenon of double sided nanostructure was comparable to the double sided multi-film anti-reflection coating. Base on this result, the double sided nanostructure technique was achievable and able to mass production for advance CMOS image sensor devices.