Optical design of dispersive metasurface nano-prism structure for high sensitivity CMOS image sensor

In this paper, a meta-photonic structure called nano-prism (NP) is designed by Full EM-wave analysis tool, rigorous coupled wave analysis (RCWA), and experimentally applied on 0.64μm pixel image sensor having 50Mp with 5mm×4mm size as a replacement of conventional μ-lens. In order to apply the NP structure to the product level image sensor, it is very important to secure not only the characteristics in direct light but also the pixel characteristics in the oblique light condition with chief ray angle (CRA). In this paper, NP design and improved pixel characteristics in the oblique light condition are described. Also, one of the key advantage of NP is that the spectral response is adjustable by arranging the pattern design without changing the color filter materials, which is verified in this paper. Furthermore, innovatively improved quantum efficiency (QE) improvement that resulted in 25% of sensitivity and 1.2dB of signal to noise ratio (SNR) improvement, and other important sensor characteristics such as auto-focus and resolution are also demonstrated in this paper.