Uncooled digital IRFPA-family with 17μm pixel-pitch based on amorphous silicon with massively parallel Sigma-Delta-ADC readout

D. Weiler; F. Hochschulz; D. Würfel; R. Lerch; T. Geruschke; S. Wall; J. Heß; Q. Wang; H. Vogt

doi:10.1117/12.2050445

24 June 2014 Uncooled digital IRFPA-family with 17μm pixel-pitch based on amorphous silicon with massively parallel Sigma-Delta-ADC readout

D. Weiler, F. Hochschulz, D. Würfel, R. Lerch, T. Geruschke, S. Wall, J. Heß, Q. Wang, H. Vogt

Author Affiliations +

Proceedings Volume 9070, Infrared Technology and Applications XL; 90701M (2014) https://doi.org/10.1117/12.2050445
Event: SPIE Defense + Security, 2014, Baltimore, MD, United States

Abstract

This paper presents the results of an advanced digital IRFPA-family developed by Fraunhofer IMS. The IRFPA-family compromises the two different optical resolutions VGA (640 ×480 pixel) and QVGA (320 × 240 pixel) by using a pin-compatible detector board. The uncooled IRFPAs are designed for thermal imaging applications in the LWIR (8 .. 14μm) range with a full-frame frequency of 30 Hz and a high thermal sensitivity. The microbolometer with a pixel-pitch of 17μm consists of amorphous silicon as the sensing layer. By scaling and optimizing our previous microbolometer technology with a pixel-pitch of 25μm we enhance the thermal sensitivity of the microbolometer. 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. To reduce production costs a chip-scale-package is used as vacuum package. This vacuum package consists of an IR-transparent window with an antireflection coating and a soldering frame which is fixed by a wafer-to-chip process directly on top of the CMOS-substrate. The chip-scale-package is placed onto a detector board by a chip-on-board technique. The IRFPAs are completely fabricated at Fraunhofer IMS on 8” CMOS wafers with an additional surface micromachining process. In this paper the architecture of the readout electronics, the packaging, and the electro-optical performance characterization are presented.

Citation Download Citation

D. Weiler, F. Hochschulz, D. Würfel, R. Lerch, T. Geruschke, S. Wall, J. Heß, Q. Wang, and H. Vogt "Uncooled digital IRFPA-family with 17μm pixel-pitch based on amorphous silicon with massively parallel Sigma-Delta-ADC readout", Proc. SPIE 9070, Infrared Technology and Applications XL, 90701M (24 June 2014); https://doi.org/10.1117/12.2050445

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