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Proceedings Paper

Improvements of a digital 25 μm pixel-pitch uncooled amorphous silicon TEC-less VGA IRFPA with massively parallel Sigma-Delta-ADC readout
Author(s): Dirk Weiler; Marco Ruß; Daniel Würfel; Renee Lerch; Pin Yang; Jochen Bauer; Jennifer Heß; Piotr Kropelnicki; Holger Vogt
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Paper Abstract

This paper presents the improvements of an advanced digital VGA-IRFPA developed by Fraunhofer-IMS. The uncooled IRFPA is designed for thermal imaging applications in the LWIR (8 .. 14 μm) range with a full-frame frequency of 30 Hz and a high sensitivity with NETD < 100 mK @ f/1. The microbolometer with a pixel-pitch of 25 μm consists of amorphous silicon as the sensing layer. The structure of the microbolometer has been optimized for a better performance compared to the 1st generation IRFPA1. The thermal isolation has been doubled by increasing the length and by decreasing the width of the legs. To increase the fill-factor the contact areas have been reduced. The microbolometers are read out by a novel readout architecture which utilizes massively parallel on-chip Sigma-Delta-ADCs. This results in a direct digital conversion of the resistance change of the microbolometer induced by incident infrared radiation. Two different solutions for the vacuum package have been developed. To reduce production costs a chip-scale-package is used. This vacuum package consists of an IR-transparent window with antireflection coating and a soldering frame which is fixed by a wafer-to-chip process directly on top of the read substrate. An alternative solution based on the use of a standard ceramic package is utilized as a vacuum package. This packaging solution is used for high performance applications. The IRFPAs are completely fabricated at Fraunhofer-IMS on 8" CMOS wafers with an additional surface micromachining process.

Paper Details

Date Published: 20 May 2011
PDF: 7 pages
Proc. SPIE 8012, Infrared Technology and Applications XXXVII, 80121F (20 May 2011); doi: 10.1117/12.883791
Show Author Affiliations
Dirk Weiler, Fraunhofer-Institut für Mikroelektronische Schaltungen und Systeme (Germany)
Marco Ruß, Fraunhofer-Institut für Mikroelektronische Schaltungen und Systeme (Germany)
Daniel Würfel, Fraunhofer-Institut für Mikroelektronische Schaltungen und Systeme (Germany)
Renee Lerch, Fraunhofer-Institut für Mikroelektronische Schaltungen und Systeme (Germany)
Pin Yang, Fraunhofer-Institut für Mikroelektronische Schaltungen und Systeme (Germany)
Jochen Bauer, Fraunhofer-Institut für Mikroelektronische Schaltungen und Systeme (Germany)
Jennifer Heß, Fraunhofer-Institut für Mikroelektronische Schaltungen und Systeme (Germany)
Piotr Kropelnicki, Fraunhofer-Institut für Mikroelektronische Schaltungen und Systeme (Germany)
Holger Vogt, Fraunhofer-Institut für Mikroelektronische Schaltungen und Systeme (Germany)


Published in SPIE Proceedings Vol. 8012:
Infrared Technology and Applications XXXVII
Bjørn F. Andresen; Gabor F. Fulop; Paul R. Norton, Editor(s)

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