High signal-to-noise ratio quantum well bolometer materials

Wissmar, Stanley; Höglund, Linda; Andersson, Jan Y.; Vieider, C.; Savage, Susan; Ericsson, Per

doi:10.1117/12.689874

Cited by 22 publications

(8 citation statements)

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“…The absorbed IR radiation generates heat that is transferred to the thermistor, resulting in a measurable change in resistance [8], [9]. This analogue signal from the pixels is transferred to the ROIC that converts it into digital format, which is finally presented as an image.…”

Section: The Pixel Structurementioning

confidence: 99%

“…This has been made possible by the innovative choice of several of the materials and key processes involved. The IR sensitive material consists of monocrystalline Si/SiGe quantum wells [8], [9]. The high TCR (in the range of 3.5% /K) and low 1/f noise of this material together with the original pixel design lead to improved bolometer performances compared to those of existing devices.…”

Section: Introductionmentioning

confidence: 99%

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High-performance long wave infrared bolometer fabricated by wafer bonding

et al. 2010

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A novel microbolometer with peak responsivity in the longwave infrared region of the electromagnetic radiation is under development at Sensonor Technologies. It is a focal plane array of pixels with a 25µm pitch, based on monocrystalline Si/SiGe quantum wells as IR sensitive material. The novelty of the proposed 3D process integration comes from the choice of several of the materials and key processes involved, which allow a high fill factor and provide improved transmission/absorption properties. Together with the high TCR and low 1/f noise provided by the thermistor material, they will lead to bolometer performances beyond those of existing devices. The thermistor material is transferred from the handle wafer to the read-out integrated circuit (ROIC) by wafer bonding. The low thermal conductance legs that connect the thermistor to the ROIC are fabricated prior to the transfer bonding and are situated under the pixel. Depending on the type of the transfer bonding used, the plugs connecting the legs to the thermistor are made before or after this bonding, resulting in two different configurations of the final structure. Using a low temperature oxide bonding and subsequent plugs formation result in through-pixel plugs. Pre-bonding plugs formation followed by thermo-compression bonding result in under-pixel plugs. The pixels are subsequently released by anhydrous vapor HF of the sacrificial oxide layer. The ROIC wafer containing the released FPAs is bonded in vacuum with a silicon cap wafer, providing hermetic encapsulation at low cost. Antireflection coatings and a thin layer getter are deposited on the cap wafer prior to bonding, ensuring high performance of the bolometer.

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Section: The Pixel Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High-performance long wave infrared bolometer fabricated by wafer bonding

et al. 2010

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“…This generic integration process has earlier been employed to also integrate thin layers of PZT 5 , shape memory alloys 6 , high-resistive and monocrystalline silicon 7,8 . In this work, a high-performance monocrystalline SiGe quantum well thermistor layer is integrated which gives a high temperature coefficient of resistance and relatively low noise as compared to amorphous thermistor materials 9 . The general process scheme of this integration process is shown in figure 1.…”

Section: Heterogeneuos Integration Of Mems Bolometers To Cmos Circuitrymentioning

confidence: 99%

Low-cost uncooled microbolometers for thermal imaging

Roxhed

Niklaus

Fischer

et al. 2010

Optical Sensing and Detection

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Cost efficient integration technologies and materials for manufacturing of uncooled infrared bolometer focal plane arrays (FPA) are presented. The technology platform enables 320x240 pixel resolution with a pitch down to 20 µm and very low NETD.A heterogeneous 3D MEMS integration technology called SOIC (Silicon-On-Integrated-Circuit) is used to combine high performance Si/SiGe bolometers with state-of-the-art electronic read-out-integrated-circuits. The SOIC integration process consists of: (a) Separate fabrication of the CMOS wafer and the MEMS wafer. (b) Adhesive wafer bonding. (c) Sacrificial removal of the MEMS handle wafer. (d) Via-hole etching. (e) Via formation and MEMS device definition. (f) Sacrificial etching of the polymer adhesive.We will present an optimized process flow that only contains dry etch processes for the critical process steps. Thus, extremely small, sub-micrometer feature sizes and vias can be implemented for the infrared bolometer arrays.The Si/SiGe thermistor is grown epitaxially, forming a mono-crystalline multi layer structure. The temperature coefficient of resistance (TCR) is primarily controlled by the concentration of Ge present in the strained SiGe layers. TCR values of more than 3%/K can be achieved with a low signal-to-noise ratio due to the mono-crystalline nature of the material. In addition to its excellent electrical properties, the thermistor material is thermally stable up to temperatures above 600 °C, thus enabling the novel integration and packaging techniques described in this paper. Vacuum sealing at the wafer level reduces the overall costs compared to encapsulation after die singulation. Wafer bonding is performed using a Cu-Sn based metallic bonding process followed by getter activation at ≥350 °C achieving a pressure in the 0.001 mbar range. After assembling, the final metal phases are stable and fully compatible with hightemperature processes. Hermeticity over the product lifetime is accomplished by well-controlled electro-deposition of metal layers, optimized bonding parameters and a suitable bond frame design.

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“…[4] Noise performance of bolometer detectors has improved by more than a factor of three in the last four years and there is no indication that performance cannot be improved any further. Main developments are focused on a number of issues:…”

Section: Fig 2 Phase a Msi Instrumentmentioning

confidence: 99%

MIBS breadboard ready for testing

Leijtens¹,

Goeij²,

Boslooper³

2017

International Conference on Space Optics — ICSO 2006

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MIBS is a spectrometer operating in the thermal infrared wavelength region, designed in frame of the phase A study for the ESA EarthCARE mission as part of the multispectral Imaging instrument MSI, which uses a 2D microbolometer array detector in stead of the more common MCT detectors.Utilization of a microbolometer and using an integrated calibration system, results in a sensor with a size and mass reduction of at least an order of magnitude when compared to currently flying instruments with similar spectral resolution. In order to demonstrate feasibility a breadboard has been designed, which will be build and aligned in 2006 and will be ready for testing the forth quarter of 2006.

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High signal-to-noise ratio quantum well bolometer materials

Cited by 22 publications

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High-performance long wave infrared bolometer fabricated by wafer bonding

High-performance long wave infrared bolometer fabricated by wafer bonding

Low-cost uncooled microbolometers for thermal imaging

MIBS breadboard ready for testing

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