Mr. Fredrik Forsberg Profile

Fredrik Forsberg

at KTH Royal Institute of Technology

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Publications (5)

Proceedings Article | 1 May 2014 Paper

High-frequency sub-wavelength IR thermal source

Floria Ottonello Briano, Pauline Renoux, Fredrik Forsberg, Hans Sohlström, Snorri Ingvarsson, Göran Stemme, Kristinn Gylfason

Proceedings Volume 9133, 91331D (2014) https://doi.org/10.1117/12.2052457

KEYWORDS: Thermography, Resistance, Platinum, Temperature metrology, Thermal modeling, Resistors, Photodetectors, Light, Infrared imaging, Nanowires

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Proceedings Article | 21 May 2011 Paper

Toward 17µm pitch heterogeneously integrated Si/SiGe quantum well bolometer focal plane arrays

Per Ericsson, Andreas Fischer, Fredrik Forsberg, Niclas Roxhed, Björn Samel, Susan Savage, Göran Stemme, Stanley Wissmar, Olof Öberg, Frank Niklaus

Proceedings Volume 8012, 801216 (2011) https://doi.org/10.1117/12.883827

KEYWORDS: Bolometers, Absorption, Quantum wells, Semiconducting wafers, Silicon, Sensors, Resistance, Infrared radiation, Reflectors, Wafer bonding

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Proceedings Article | 14 May 2010 Paper

Low-cost uncooled microbolometers for thermal imaging

Niclas Roxhed, Frank Niklaus, Andreas Fischer, Fredrik Forsberg, Linda Höglund, Per Ericsson, Björn Samel, Stanley Wissmar, Anders Elfving, Tor Ivar Simonsen, Kaiying Wang, Nils Hoivik

Proceedings Volume 7726, 772611 (2010) https://doi.org/10.1117/12.855752

KEYWORDS: Bolometers, Semiconducting wafers, Wafer bonding, Germanium, Tin, Infrared bolometers, Copper, Readout integrated circuits, Microelectromechanical systems, Quantum wells

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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.

SPIE Journal Paper | 1 March 2009

Three-dimensional selective imaging of sound sources

Erik Olsson, Fredrik Forsberg

OE, Vol. 48, Issue 03, 035801, (March 2009) https://doi.org/10.1117/12.10.1117/1.3093609

KEYWORDS: Transducers, Reconstruction algorithms, 3D image processing, Digital holography, Tomography, Phase measurement, Sensors, Radio propagation, Acoustics, Vibrometry

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Proceedings Article | 30 May 2003 Paper

Internal deformation and velocity field measurements by use of digital speckle radiography

Fredrik Forsberg, Stephen Grantham

Proceedings Volume 5144, (2003) https://doi.org/10.1117/12.500493

KEYWORDS: Speckle, X-rays, Particles, Image processing, Opacity, Tungsten, Speckle pattern, Digital signal processing, Motion measurement, Sensors

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