7.5µm and 5µm pitch IRFPA developments in MWIR at CEA-LETI

Bisotto, Sylvette; Abergel, J.; Dupont, Bertrand; Ferron, A.; Mailliart, Olivier; Nicolas, Jean-Alain; Renet, S.; Rochette, F.; Santailler, Jean‐Louis

doi:10.1117/12.2519330

Cited by 6 publications

(4 citation statements)

References 4 publications

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“…Smaller pixel pitches are the key to meet the requirements [10]. Previous works have been presented by CEA-LETI on non-p diode technology with 10, 7.5 and 5 µm pixel pitch [11] [12] and more recently on p-on-n technology [13] with superpixels made of 4 7.5 µm pitch diodes. This achievement was possible with the instruction of a new generation (NG) of p-on-n diode technology, developed by CEA-LETI and Lynred, which improves both manufacturability and noise performances.…”

Section: Introductionmentioning

confidence: 99%

Small pixel pitch MCT P on N MWIR photodiodes at DEFIR: towards 7.5um and beyond with very high image quality

Baier

Gravrand

LeGoff

et al. 2023

Infrared Technology and Applications XLIX

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MCT p-on-n photodiodes manufactured at Lynred and CEA-LETI have demonstrated state of the art performances for HOT applications. On blue and red mid infrared bands on 15μm pixel pitch, respectively 150 and 130K operating temperatures have been obtained, due to diffusion limited dark current and low defectivity. To achieve equivalent results on smaller pixel, the p-on-n technology at DEFIR, joint laboratory between Lynred and CEA-LETI, has been improved. The technological process was modified to ensure a proper diode formation and to efficiently passivate the interface between MCT and encapsulation layers, especially in the vicinity of the space charge region. The manufactured arrays with a 5.3μm cutoff wavelength have been hybridized on a digital output SXGA (1280×1024) direct injection ROIC with a pixel pitch of 7.5 μm. This paper present the measured current, blackbody responsivity and RMS noise on FPAs with F/4 numerical aperture. We will also discuss spectral response, quantum efficiency, shot-noise limited photodiodes and noise histograms shapes and their distribution tails at 130K. The very low number of defective pixel allow to address higher operating temperature and measurements have been performed at 140K and even 150K with very limited performance degradation. Pixel pitch of 5 μm has been characterized on test chips and present I-V curves with low dispersion and long bias plateau. As for larger pixel sizes, these photodiodes are shot-noise limited. Modulation transfer function has been measured by electron beam induced current and presents high value, up to 56%.

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Section: Introductionmentioning

confidence: 99%

Small pixel pitch MCT P on N MWIR photodiodes at DEFIR: towards 7.5um and beyond with very high image quality

Baier

Gravrand

LeGoff

et al. 2023

Infrared Technology and Applications XLIX

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“…This strategy was successfully practiced for 384x288, 24µm pitch followed by 640x512, 15µm pitch MWIR modules and then advanced to 1024x768, 10µm pitch MWIR modules 1 . In the course of pitch size reduction, a 5µm pixel is intensively pursued by several detector manufacturers as the ultimate goal for MWIR FPAs 2,3,4,5,6 . During this endeavor, a 7.5µm pixel pitch has been realized at AIM as next step in miniaturization using an SXGA-format (1280x1024) 6 .…”

Section: Introductionmentioning

confidence: 99%

Low SWaP MWIR and LWIR modules with small pixel pitch

Lutz

Breiter

Eich

et al. 2023

Infrared Technology and Applications XLIX

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Pixel pitch reduction as well as high operating temperatures (HOT) of IR focal plane arrays (FPA) have attracted huge development effort in recent years. While the development journey is continuously moving towards an ultra-small pixel pitch of ~5µm for MWIR FPAs by several manufacturers, for their LWIR pendants the focus has not been on pitch size reduction and HOT so far. This comes as a surprise, since low SWaP (size, weight and power) LWIR modules in combination with high spatial resolution are of great interest due to their superior electro-optical (e/o) performance in particular for scenarios with degraded visual environment. An SXGA-format (1280x1024 pixels) MWIR module using a 7.5µm pixel pitch is currently under development at AIM. Excellent performance data were obtained with the first prototypes up to elevated operating temperatures of ~150K thanks to the AIM HOT MCT p/n detector technology. SWaP characteristics are analyzed for both a compact configuration using the in-house 'SX035' cooler and for an even smaller variant referred to as 'HOT Cube SX'. Moreover, a low SWaP VGA-format MWIR module is under development at AIM using a 10µm pixel and a HOT rotary cooler. First measurement results will be shown.Promising first e/o data of XGA-format 10µm pitch LWIR FPAs manufactured in a planar MCT p/n technology have already been presented by AIM last year. Recently, the performance has been improved which is underlined by a high thermal resolution of ~30mk and a low level of noisy pixel at HOT of ~100K. Latest results as well as key features of the possible low SWaP IR-module configurations will be discussed.

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“…Current visible-image sensors employed in commercial mobile cameras have pixel sizes ranging between 1 and 2 µm, and complementary metal oxide semiconductor (CMOS) image sensors have recently been developed with 0.7 µm pixels, both of which approach the diffraction limit at their respective detection wavelengths [8,9]. Meanwhile, the detector size of infrared (IR) image sensors is currently limited to 4-5 µm regardless of the detection wavelength band [10,11]. This is mainly because the fabrication of IR imagers typically requires hybridization of the focal plane array (FPA) with the CMOS read-out integrated circuit (ROIC), which are different material systems and substrates.…”

Section: Introductionmentioning

confidence: 99%

Toward sub-micron pixels for short-wave infrared imaging

Kang¹,

Rabinowitz²,

Bianconi³

et al. 2022

Semicond. Sci. Technol.

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The sensitivity of infrared imagers can be significantly improved by reducing the size of photodetectors down to the diffraction limit. Emerging low-dimensional material enable submicron photodetectors, which can be diffraction limited and lead to significant sensitivity improvement in the critical short-wave infrared band. However, reaching this limit requires pixel sizes smaller than the metal bumps needed for hybridization to silicon readout chips. Such tiny fragile pixels are susceptible to damages due to the mechanical pressure applied during flip-chip bonding, degrading the number of functional camera pixels. Herein, we systematically characterize the influence of the detector size on the imager pixel yield. We then introduce strategies for improving the yield of sub-micron pixels from less than half of total pixels to more than 3/4 of them. While we used a top-down fabrication for our detectors, the developed method is also applicable to bottom-up fabrication methods to make highly sensitive infrared cameras based on emerging low-dimensional material such as catalyst-assisted nanowires.

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7.5µm and 5µm pitch IRFPA developments in MWIR at CEA-LETI

Cited by 6 publications

References 4 publications

Small pixel pitch MCT P on N MWIR photodiodes at DEFIR: towards 7.5um and beyond with very high image quality

Small pixel pitch MCT P on N MWIR photodiodes at DEFIR: towards 7.5um and beyond with very high image quality

Low SWaP MWIR and LWIR modules with small pixel pitch

Toward sub-micron pixels for short-wave infrared imaging

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