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Proceedings Paper • Open Access

CMOS sensors for atmospheric imaging
Author(s): Jérôme Pratlong; David Burt; Paul Jerram; Frédéric Mayer; Andrew Walker; Robert Simpson; Steven Johnson; Wendy Hubbard

Paper Abstract

Recent European atmospheric imaging missions have seen a move towards the use of CMOS sensors for the visible and NIR parts of the spectrum. These applications have particular challenges that are completely different to those that have driven the development of commercial sensors for applications such as cell-phone or SLR cameras. This paper will cover the design and performance of general-purpose image sensors that are to be used in the MTG (Meteosat Third Generation) and MetImage satellites and the technology challenges that they have presented. We will discuss how CMOS imagers have been designed with 4T pixel sizes of up to 250 μm square achieving good charge transfer efficiency, or low lag, with signal levels up to 2M electrons and with high line rates. In both devices a low noise analogue read-out chain is used with correlated double sampling to suppress the readout noise and give a maximum dynamic range that is significantly larger than in standard commercial devices. Radiation hardness is a particular challenge for CMOS detectors and both of these sensors have been designed to be fully radiation hard with high latch-up and single-event-upset tolerances, which is now silicon proven on MTG. We will also cover the impact of ionising radiation on these devices. Because with such large pixels the photodiodes have a large open area, front illumination technology is sufficient to meet the detection efficiency requirements but with thicker than standard epitaxial silicon to give improved IR response (note that this makes latch up protection even more important). However with narrow band illumination reflections from the front and back of the dielectric stack on the top of the sensor produce Fabry-Perot étalon effects, which have been minimised with process modifications. We will also cover the addition of precision narrow band filters inside the MTG package to provide a complete imaging subsystem. Control of reflected light is also critical in obtaining the required optical performance and this has driven the development of a black coating layer that can be applied between the active silicon regions.

Paper Details

Date Published: 25 September 2017
PDF: 9 pages
Proc. SPIE 10562, International Conference on Space Optics — ICSO 2016, 105622N (25 September 2017); doi: 10.1117/12.2296044
Show Author Affiliations
Jérôme Pratlong, Teledyne e2v UK Ltd. (United Kingdom)
David Burt, e2v Technologies (United Kingdom)
Paul Jerram, e2v Technologies (United Kingdom)
Frédéric Mayer, e2v semiconductors (France)
Andrew Walker, e2v technologies (United Kingdom)
Robert Simpson, e2v technologies (United Kingdom)
Steven Johnson, e2v technologies (United Kingdom)
Wendy Hubbard, e2v technologies (United Kingdom)

Published in SPIE Proceedings Vol. 10562:
International Conference on Space Optics — ICSO 2016
Bruno Cugny; Nikos Karafolas; Zoran Sodnik, Editor(s)

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