The Broadband Radiometer (BBR) is an instrument being developed for the ESA EarthCARE satellite. The BBR instrument objective is to provide measurements of the reflected short-wave (0.25-4.0 μm) and emitted long-wave (4.0-50 μm) top of the atmosphere (TOA) radiance over three along-track views (forward, nadir and backward). The instrument has three fixed telescopes, one for each view, each containing a broadband detector. The BBR instrument is led by SEA in the UK with RAL responsible for the BBR optics unit (OU) while EADS Astrium is the EarthCARE prime contractor. A detailed description of the instrument is provided in .
The BBR detectors consist in three dedicated assemblies under the responsibility of INO. The detectors development started in 2008 and led to the design and implementation of a new gold black deposition facility at INO , in parallel with the preliminary and detailed design phases of the detector assemblies. As of today, two breadboard models and one engineering model have been delivered to RAL. In the BBR OU each detector mechanically interfaces with the telescope and electrically with the front-end electronics (FEE). The detectors’ development is now at the Critical Design Review (CDR) level.
This paper first provides a description of the detector design along with its principles of operation. It further presents and discusses measurement and analysis results for the performance characterization of the engineering model in the context of the applicable requirements. Detector-level qualification planning is finally discussed.
The Broadband Radiometer (BBR) is an instrument being developed for the ESA EarthCARE satellite. The BBR
instrument objective is to provide measurements of the reflected short-wave (0.25-4.0 μm) and emitted long-wave (4.0-
50 μm) TOA radiance over three along-track views (forward, nadir and backward). The instrument has three fixed
telescopes, one for each view, each containing a broadband detector. Each detector consists of an uncooled focal plane
array (FPA) hybridized with a readout integrated circuit (ROIC) and a proximity electronics circuit-card assembly
(CCA) packaged in an aluminum base plate with cover. The detectors, based on INO's VOx microbolometer technology,
are required to provide fast pixel response time (< 6 ms), uniform spectral response over the entire spectral range
(achieved by the development of a gold black absorber), and low NEDT under the instrument operating conditions. The
detectors development has now passed the critical design review (CDR) and various development units (among which
the most recent is the engineering model (EM)) have been shown to meet the specification requirements. This paper first
provides a description of the detector design, followed by its principles of operation. It further presents and discusses
measurement and analysis results for the performance characterization of the engineering model in the context of the
In the MEMS manufacturing world, the "fabless" model is getting increasing importance in recent years as a way for
MEMS manufactures and startups to minimize equipment costs and initial capital investment. In order for this model to
be successful, the fabless company needs to work closely with a MEMS foundry service provider. Due to the lack of
standardization in MEMS processes, as opposed to CMOS microfabrication, the experience in MEMS development
processes and the flexibility of the MEMS foundry are of vital importance.
A multidisciplinary team together with a complete microfabrication toolset allows INO to offer unique MEMS foundry
services to fabless companies looking for low to mid-volume production. Companies that benefit from their own
microfabrication facilities can also be interested in INO's assistance in conducting their research and development work
during periods where production runs keep their whole staff busy. Services include design, prototyping, fabrication,
packaging, and testing of various MEMS and MOEMS devices on wafers fully compatible with CMOS integration.
Wafer diameters ranging typically from 1 inch to 6 inches can be accepted while 8-inch wafers can be processed in some
instances. Standard microfabrication techniques such as metal, dielectric, and semiconductor film deposition and
etching as well as photolithographic pattern transfer are available. A stepper permits reduction of the critical dimension
to around 0.4 μm. Metals deposited by vacuum deposition methods include Au, Ag, Al, Al alloys, Ti, Cr, Cu, Mo,
MoCr, Ni, Pt, and V with thickness varying from 5 nm to 2 μm. Electroplating of several materials including Ni, Au and
In is also available. In addition, INO has developed and built a gold black deposition facility to answer customer's needs
for broadband microbolometric detectors. The gold black deposited presents specular reflectance of less than 10% in the
wavelength range from 0.2 μm to 100 μm with thickness ranging from 20 to 35 μm and a density of 0.3% the bulk
density of gold. Two Balzers thin-film deposition instruments (BAP-800 and BAK-760) permit INO to offer optical thin
film manufacturing. Recent work in this field includes the design and development of a custom filter for the James
Webb Space Telescope (JWST) as collaboration with the Canadian company ComDEV. An overview of the different
microfabrication foundry services offered by INO will be presented together with the most recent achievements in the
field of MEMS/MOEMS.
THz imaging is a very promising field rapidly growing in importance. This expanding field is at its early stage of
development but already a large number of applications are foreseen. THz imaging promises to be a key technology in
various fields, such as defense & security where it can be used to defeat camouflage. Based on its many years of
experience in uncooled bolometers technology, INO has developed, assembled and characterized a prototype THz
imager. The camera's 160 × 120 pixel array consists of pixels with a 52 μm pitch that have been optimized for the THz
region. Custom camera electronics and an F/1 THz lens barrel complete the imager design. Real-time imaging at video
rate of 30 frame/sec has been performed with a 3 THz quantum cascade laser set-up. THz images of numerous object-obscurant
combinations are presented, proving the feasibility of video imaging in security screening applications.
The Broadband Radiometer (BBR) is an instrument being developed for the ESA EarthCARE satellite. The BBR
instrument objective is to provide top-of-atmosphere (TOA) radiance measurements in two spectral channels, and over
three along-track directions. The instrument has three fixed telescopes (one for each view) each containing a broadband
detector. Each detector consists of an uncooled 30-pixel linear focal plane array (FPA) coated with gold black in order to
ensure uniform spectral responsivity from 0.2 μm to 50 μm. The FPA is hybridized with a readout integrated circuit
(ROIC) and a proximity electronics circuit-card assembly (CCA) packaged in an aluminum base plate with cover. This
paper provides a technical description of the detector design and operation. Performance data at the FPA pixel level as
well as unit-level test results on early prototypes of the detectors are also presented.
We have previously reported on the initial development of a multi-linear uncooled microbolometer FPA for
space applications. The IRL512 FPA features three parallel lines of 512 pixels on a 39 micron pixel pitch
with parallel integration of all pixels, a complete detector bridge per pixel for offset and substrate
temperature drift compensation, and one 14-bit digital output bus per line. The FPA achieves an NETD
below 45 mK over the LWIR spectral band with 50 ms integration time, 300 K scene temperature, and
f/0.87 optics. In the context of the NIRST instrument for the upcoming SAC-D/Aquarius earth observation
mission, MWIR and LWIR optimized versions of the IRL512 in radiometric packages including integrated
stripe filter and radiation shield have recently successfully undergone screening and qualification
campaigns. The qualification strategy consists of part element and device qualification including proton
and total dose radiation, shock, vibration, burn-in, and thermal cycling. The test conditions and results will
be reviewed. The thermal resolution of the current generation of radiometrically packaged IRL512 FPA in
the NIRST instrument is below 500 mK with an 0.9 micron spectral bandwidth centred at 10.85 μm, 50 ms
integration time, the NIRST f/1 optics, and 300 K scene temperature.
INO has established a VOx-based uncooled microbolometer detector technology and an expertise in the development of
custom detectors and focal plane arrays. Thanks to their low power consumption and broadband sensitivity, uncooled
microbolometer detectors are finding an increased number of applications in the field of space-based thermal remote
sensing. A mission requirement study has identified at least seven applications with a need for data in the MWIR (3-8
μm), LWIR (8-15 μm) and or FIR (15-100 μm) wavelength bands. The requirement study points to the need for two
main classes of uncooled thermal detectors, the first requiring small and fast detectors for MWIR and LWIR imaging
with small ground sampling distance, and the second requiring larger detectors with sensitivity out to the FIR. In this
paper, the simulation, design, microfabrication and radiometric testing of detectors for these two classes of requirements
will be presented. The performance of the experimental detectors closely approach the mission requirements and show
the potential of microbolometer technology to fulfill the requirements of future space based thermal imaging missions.
Micro-Electro-Mechanical Systems (MEMS) packaging constitutes most of the cost of such devices. For the integration
of MEMS with microelectronics systems to be widespread, a drastic reduction of the overall price is required. Wafer-level-packaging allows a fundamental reduction of the packaging cost by combining wafer-level microfabrication
techniques with wafer-to-wafer bonding. To achieve the vacuum atmosphere required for the operation of many MEMS
devices, bonding techniques such as anodic bonding, eutectic bonding, fusion bonding and gold to gold thermocompression
bonding have been utilized, which require relatively high temperatures (>300°C) being in some cases
incompatible with MEMS and microelectronics devices. Furthermore, to maintain vacuum integrity over long periods of
time, getters requiring high activation temperatures are usually employed.
INO has developed a hybrid wafer-level micropackaging technology based on low temperature fluxless solder joints in
which the micropackaged MEMS device is not exposed to a temperature over 150°C. The micropackages have been
designed for 160×120 microbolometer FPAs. Ceramic spacers are patterned by standard microfabrication techniques
followed by laser micromachining. AR-coated floatzone silicon IR windows are patterned with a solderable layer. Both,
microbolometer dies and windows are soldered to the ceramic tray by a combination of solder paste stencil printing,
reflow and fluxless flip-chip bonding. A low temperature getter is also introduced to control outgassing of moisture and
CO2 during the lifetime of the package. Vacuum sealing is carried out by locally heating the vacuum port after bake out
of the micropackages. In this paper, the vacuum integrity of micropackaged FPA dies will be reported. Base pressures as
low as 5 mTorr and equivalent flow rates at room temperature of 4×10-14 Torr.l/s without getter incorporation have been
demonstrated using integrated micro-pressure gauges. A study of the influence of different packaging parameters on the
lifetime of micropackages will be presented.
Linear detector array formats are suitable for applications where relative motion between the detector and scene provides an intrinsic scanning mechanism, such as industrial inspection systems and satellite-based earth and planetary observation. The linear array format facilitates the introduction readout features not available in 2-D formats and when combined with low cost packaging approaches reduces sensor cost. We present two linear uncooled detector arrays based on VOx microbolometer technology and integrated CMOS readout electronics. The IRL256B is a linear array of 256 detectors on a 52 μm pitch. It includes a parallel array of 256 reference detectors to provide coarse offset correction and substrate temperature drift compensation. The IRL512A consists of 3 parallel lines of 512 pixels on a 39 μm pitch. It is particularly well suited to multi-spectral pushbroom imaging applications. Each pixel includes active and reference detectors to reduce pixel offset, eliminate common mode power supply noise and increase immunity to chip temperature drift. All pixels are integrated in parallel and the data are output in 14-bit digital format on three parallel output buses. The microbolometer detector design can be customized for selected wavelength ranges from NIR to VLWIR. The IRL256B has been integrated in industrial thermal line-scan imagers and spectrometers and may also be employed in uncooled airborne imaging and scanned surveillance or inspection systems. The IRL512A has been selected as the baseline detector for a number of future earth observation satellite missions.