A High Near-Infrared Sensitivity over 70-dB SNR CMOS Image Sensor with Lateral Overflow Integration Trench Capacitor

Maasa Murata, Rihito Kuroda, Yasuyuki Fujihara, Yusuke Otsuka, Hiroshi Shibata, Taku Shibaguchi, Yutaka Kamata, Noriyuki Miura, Naoya Kuriyama, Shigetoshi Sugawa

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

This article presents a 16- \mu \text{m} pitch CMOS image sensor (CIS) exhibiting a high near-infrared (NIR) sensitivity and a 71.3-dB signal-to-noise ratio (SNR) with a linear response for high-precision absorption imaging. A 1.6-pF lateral overflow integration trench capacitor (LOFITreC) was introduced in each pixel to achieve a very high full well capacity (FWC), and a very low impurity concentration p-type Cz-Si substrate with a low oxygen concentration was employed for improving the NIR sensitivity. The developed CIS operated at a single exposure linear response wide dynamic range (DR) mode and a dual reset voltage mode for high SNR absorption imaging and achieved the maximum 24.3 Me- FWC, a wide spectral sensitivity from 200 to 1100 nm, and a photodiode quantum efficiency of 89.7%, 78.2%, and 26.7% at 860, 940, and 1050 nm, respectively. Both the spatial resolution and light sensitivity toward the NIR light were further improved by thinning the Si substrate and by applying a negative backside bias. Due to the LOFITreC, a record spatial efficiency of 95 ke ^{-}/\mu \text{m}^{{2}} with a 130-dB DR was achieved. As one of the applications of the developed CIS, the NIR absorption imaging toward a noninvasive blood glucose measurement was experimented and a diffusion of 5 mg/dl glucose was clearly visualized at 1050 nm in real time.

Original languageEnglish
Article number9031733
Pages (from-to)1653-1659
Number of pages7
JournalIEEE Transactions on Electron Devices
Volume67
Issue number4
DOIs
Publication statusPublished - 2020 Apr 1

Keywords

  • Absorption imaging
  • CMOS image sensor (CIS)
  • Lateral overflow integration trench capacitor (LOFITreC)
  • Near-infrared (NIR) light
  • Signal-to-noise ratio (SNR)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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