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Design and Performance of a Pinned Photodiode CMOS Image Sensor Using Reverse Substrate Bias

Stefanov, Konstantin D.; Clarke, Andrew S.; Ivory, James and Holland, Andrew D. (2018). Design and Performance of a Pinned Photodiode CMOS Image Sensor Using Reverse Substrate Bias. Sensors, 18(1), article no. 118.

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A new pinned photodiode (PPD) CMOS image sensor with reverse biased p-type substrate has been developed and characterized. The sensor uses traditional PPDs with one additional deep implantation step to suppress the parasitic reverse currents, and can be fully depleted. The first prototypes have been manufactured on an 18 µm thick, 1000 Ω·cm epitaxial silicon wafers using 180 nm PPD image sensor process. Both front-side illuminated (FSI) and back-side illuminated (BSI) devices were manufactured in collaboration with Teledyne e2v. The characterization results from a number of arrays of 10 µm and 5.4 µm PPD pixels, with different shape, the size and the depth of the new implant are in good agreement with device simulations. The new pixels could be reverse-biased without parasitic leakage currents well beyond full depletion, and demonstrate nearly identical optical response to the reference non-modified pixels. The observed excessive charge sharing in some pixel variants is shown to not be a limiting factor in operation. This development promises to realize monolithic PPD CIS with large depleted thickness and correspondingly high quantum efficiency at near-infrared and soft X-ray wavelengths.

Item Type: Journal Item
Copyright Holders: 2018 The Authors
ISSN: 1424-8220
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetRP10G0348A01UK Space Agency (UKSA)
Keywords: CMOS image sensors (CIS); pinned photodiode; full depletion; reverse bias; thermionic emission
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Centre for Electronic Imaging (CEI)
Item ID: 52791
Depositing User: Konstantin Stefanov
Date Deposited: 05 Jan 2018 14:38
Last Modified: 02 Jun 2019 11:11
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