This paper presents the ongoing development of a laser ionization mass spectrometric system to be applied for screening
for security related threat substances, specifically explosives. The system will be part of a larger security checkpoint
system developed and demonstrated within the FP7 project EFFISEC to aid border police and customs at outer border
checks. The laser ionization method of choice is SPI (single photon ionization), but the system also incorporates optional
functionalities such as a cold trap and/or a particle concentrator to facilitate detection of minute amounts of explosives.
The possibility of using jet-REMPI as a verification means is being scrutinized. Automated functionality and user
friendliness is also considered in the demo system development.
The main objective of this project is to study the difference between aged and un-aged post-blast residues and nonblasted
Sand from the post-blast scenes was subjected to accelerated aging (temperature, light and addition of water) over a
period of 20 weeks. The samples were aged as matrix-free pure compounds and as post-blast sand. Several explosive
materials were detonated over sand-filled containers and selected residues were separated and detected with HPLC/UV.
Separation and detection methods using GC/MS and LC/UV were developed.
This screening study of aged post-blast residues revealed that most of the residues reached low or undetectable
concentration within a period of eight weeks of aging. This degradation rate theory can be applied both for the
temperature- and UV-aged samples. The half-life degradation time (t<sub>1/2</sub>) was estimated and most of the detected residues
reach t<sub>1/2</sub> within five weeks. No trends with significant difference can be seen between the UV- and temperature-aged
Far infrared (FIR) is becoming more widely accepted within the automotive industry as a powerful sensor to detect
Vulnerable Road Users like pedestrians and bicyclist as well as animals. The main focus of FIR system development lies
in reducing the cost of their components, and this will involve optimizing all aspects of the system. Decreased pixel size,
improved 3D process integration technologies and improved manufacturing yields will produce the necessary cost
reduction on the sensor to enable high market penetration.
The improved 3D process integration allows a higher fill factor and improved transmission/absorption properties.
Together with the high Thermal Coefficient of Resistance (TCR) and low 1/f noise properties provided by
monocrystalline silicon germanium SiGe thermistor material, they lead to bolometer performances beyond those of
existing devices. The thermistor material is deposited and optimized on an IR wafer separated from the read-out
integrated circuit (ROIC) wafer. The IR wafer is transferred to the ROIC using CMOS compatible processes and
materials, utilizing a low temperature wafer bonding process. Long term vacuum sealing obtained by wafer scale
packaging enables further cost reductions and improved quality. The approach allows independent optimization of ROIC
and thermistor material processing and is compatible with existing MEMS-foundries, allowing fast time to market.
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
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.
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.
Ge islands fabricated on Si(100) by molecular beam epitaxy at different growth temperatures, were studied using crosssectional
scanning transmission electron microscopy and energy-dispersive X-ray spectrometry combined with electron energy loss spectrometry experiments. The island size, shape, strain, and material composition define the dot-related optical transition energies, but they are all strongly dependent on the growth temperature. We have performed quantitative investigations of the material composition of Ge/Si(001) quantum dots. The samples were grown at temperatures ranging from 430 to 730 <sup>o</sup>C, with one buried and one uncapped layer of Ge islands separated by 140 nm intrinsic Si. The measurements showed a Ge concentration very close to 100 % in the islands of samples grown at 430 <sup>o</sup>C. With a growth temperature of 530 <sup>o</sup>C, a ~20 % reduction of the Ge fraction was observed, which is due to intermixing of Si and Ge. This is consistent with our previous photoluminescence results, which revealed a significant blue shift of the Ge dot-related emission peak in this growth temperature range. The Ge concentration decreases more slowly when the growth temperature is increased above 600 <sup>o</sup>C, which can be explained by geometrical arguments. The longer distance between the interface and the core of these larger sized dome-shaped islands implies that less Si atoms reach the dot center. In general, the uncapped Ge dots have similar widths as the embedded islands, but the height is almost exclusively larger. Furthermore, the Ge concentration is slightly lower for the overgrown dots.