Optimization of CMOS image sensors with single photon-trapping hole per pixel for enhanced sensitivity in near-infrared

TL;DR

This paper presents a novel CMOS sensor design with a single photon-trapping hole per pixel, significantly improving near-infrared sensitivity and reducing crosstalk through optimized hole dimensions and trench structures.

Contribution

It introduces a new pixel architecture with a single photon-trapping hole that enhances optical absorption and reduces crosstalk in CMOS sensors for near-infrared imaging.

Findings

Optical absorption increased by 60% with optimized hole dimensions.

Crosstalk reduced using thin trenches between pixels.

Enhanced sensitivity across blue, green, red, and infrared wavelengths.

Abstract

The optimization of silicon photodiode-based CMOS sensors with backside-illumination for 300-1000 nm wavelength range was studied. It was demonstrated that a single hole on a photodiode increases the optical efficiency of the pixel in near-infrared wavelengths. A hole with optimal dimensions enhanced optical absorption by 60% for a 3 $\mu$m thick Si photodiode, which is 4 orders better than that for comparable flat photodiodes. We have shown that there is an optimal size and depth of the hole that exhibits maximal absorption in blue, green, red, and infrared. Crosstalk was successfully reduced by employing thin trenches between pixels of 1.12 $\mu{m^2}$ in size.