Abstract

Near-infrared (NIR) sensing technology using CMOS image sensors is used in many applications, including automobiles, biological inspection, surveillance, and mobile devices. An intuitive way to improve NIR sensitivity is to thicken the light absorption layer (silicon). However, thickened silicon lacks NIR sensitivity and has other disadvantages, such as diminished optical performance (e.g. crosstalk) and difficulty in processing. In this paper, a pixel structure for NIR sensing using a stacked CMOS image sensor is introduced. There are two photodetection layers, a conventional layer and a bottom photodiode, in the stacked CMOS image sensor. The bottom photodiode is used as the NIR absorption layer. Therefore, the suggested pixel structure does not change the thickness of the conventional photodiode. To verify the suggested pixel structure, sensitivity was simulated using an optical simulator. As a result, the sensitivity was improved by a maximum of 130% and 160% at wavelengths of 850 nm and 940 nm, respectively, with a pixel size of 1.2 μm. Therefore, the proposed pixel structure is useful for NIR sensing without thickening the silicon.

© 2023 Optical Society of Korea

Near-IR absorption enhancement and crosstalk reduction of a photodiode in a CMOS indirect time-of-flight sensor

Xiang Liu, Chenyan Geng, Xuesong Ji, Shuyu Lei, and Bing Zhang
Appl. Opt. 61(22) 6577-6583 (2022)

Near-infrared sensitivity improvement by plasmonic diffraction for a silicon image sensor with deep trench isolation filled with highly reflective metal

Atsushi Ono, Kazuma Hashimoto, and Nobukazu Teranishi
Opt. Express 29(14) 21313-21319 (2021)

Photon confinement in a silicon cavity of an image sensor by plasmonic diffraction for near-infrared absorption enhancement

Takahito Yoshinaga, Kazuma Hashimoto, Nobukazu Teranishi, and Atsushi Ono
Opt. Express 30(20) 35516-35525 (2022)

Fast High-Sensitivity Silicon Photodiodes

R. L. Williams
J. Opt. Soc. Am. 52(11) 1237-1244 (1962)

Design of a CMOS image sensor pixel with embedded polysilicon nano-grating for near-infrared imaging enhancement

Elie Cobo, Sébastien Massenot, Alexandre Le Roch, Franck Corbière, Vincent Goiffon, Pierre Magnan, and Jean-Luc Pelouard
Appl. Opt. 61(4) 960-968 (2022)