Micromachined bolometers on polyimide

This paper presents design, fabrication and measured performance parameters of micromachined infrared detectors on polyimide substrates. The detectors are of bolometer type made of semiconducting yttrium–barium–copper oxide (YBCO) as the thermometer material and are built on a 40–50m-thick layer of polyimide (PI5878G) that serves as a flexible substrate. A thin film of Si3N4 supports the detectors. Surface micromachining is used to isolate the detectors and the supporting nitride layer from the substrate. Despite being supported by a layer of Si3N4, an average thermal conductivity of 5.61 × 10 −7 W/K, comparable to self-supporting devices on flexible substrates has been measured. This opens the possibility of placing such flexible sensors on micromachined membranes, integrated with other functions such as pressure sensing to build “Smart Skin.” Roomtemperature responsivity of 7.4 × 10 3 V/W and detectivity of 6.6 × 10 5 cm Hz 1/2 /W were demonstrated on 40m × 40m microbolometers. The effect of substrate heating was also investigated and was found not to cause cross talk between the pixels. If these sensors are to be used as part of multi-functional, flexible sensor systems, device-level vacuum packaging is necessary. This was investigated using computer simulations for structural analysis and found to be feasible. © 2006 Elsevier B.V. All rights reserved.

[1]  Neal R. Butler,et al.  Ambient temperature IR focal plane arrays , 2000, Defense, Security, and Sensing.

[2]  P. Kruse,et al.  Uncooled infrared imaging arrays and systems , 1997 .

[3]  Donald P. Butler,et al.  MgO sacrificial layer for micromachining uncooled Y-Ba-Cu-O IR microbolometers on Si/sub 3/N/sub 4/ bridges , 1999 .

[4]  Daniel F. Murphy,et al.  320 x 240 silicon microbolometer uncooled IR FPAs with on-chip offset correction , 1996, Defense + Commercial Sensing.

[5]  Daniel F. Murphy,et al.  Microbolometer uncooled infrared camera with 20-mK NETD , 1998, Defense, Security, and Sensing.

[6]  Thomas B. Breen,et al.  Applications of uncooled microbolometer sensors , 1998, Defense, Security, and Sensing.

[7]  Robert E. Higashi,et al.  Monolithic two-dimensional arrays of micromachined microstructures for infrared applications , 1998, Proc. IEEE.

[8]  G. Stemme,et al.  Thermal characterization of surface-micromachined silicon nitride membranes for thermal infrared detectors , 1997 .

[9]  A. Tanaka,et al.  Silicon IC Process Compatible Bolometer Infrared Focal Plane Array , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[10]  Jean-Louis Ouvrier-Buffet,et al.  Amorphous-silicon-based uncooled microbolometer IRFPA , 1999, Defense, Security, and Sensing.

[11]  Gamani Karunasiri,et al.  Performance of titanium and amorphous germanium microbolometer infrared detectors , 1999, Other Conferences.

[12]  Stephen J. Matthews.  Thermal imaging on the rise , 2004 .

[13]  Aasutosh Dave,et al.  Wafer-level self-packaged infrared microsensors , 2004, SPIE Defense + Commercial Sensing.

[14]  Donald P. Butler,et al.  A semiconductor YBaCuO microbolometer for room temperature IR imaging , 1997 .

[15]  E. Dereniak,et al.  Infrared Detectors and Systems , 1996 .

[16]  Donald P. Butler,et al.  Semiconducting YBaCuO thin films for uncooled infrared bolometers , 1995 .

[17]  John F. Brady,et al.  Advances in amorphous silicon uncooled IR systems , 1999, Defense, Security, and Sensing.

[18]  K. Najafi,et al.  Vacuum packaging technology using localized aluminum/silicon-to-glass bonding , 2002, Technical Digest. MEMS 2001. 14th IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.01CH37090).

[19]  Peter Taylor,et al.  Amber's uncooled microbolometer LWIR camera , 1996, Defense + Commercial Sensing.

[20]  J. Wauters,et al.  Doped silicon creates new bolometer material , 1997 .

[21]  Mahmoud Almasri,et al.  Self-supporting uncooled infrared microbolometers with low-thermal mass , 2001 .

[22]  Z. Çelik-Butler,et al.  Fabrication of semiconducting YBaCuO surface-micromachined bolometer arrays , 1997 .

[23]  Robert S. Wilson,et al.  Prelaunch calibrations of the Clouds and the Earth's Radiant Energy System (CERES) Tropical Rainfall Measuring Mission and Earth Observing System morning (EOS-AM1) spacecraft thermistor bolometer sensors , 1998, IEEE Trans. Geosci. Remote. Sens..

[24]  Shadi A. Dayeh,et al.  Micromachined infrared bolometers on flexible polyimide substrates , 2005 .

[25]  John F. Brady,et al.  Low-cost low-power uncooled a-Si-based micro infrared camera for unattended ground sensor applications , 1999, Defense, Security, and Sensing.

[26]  C. Falcony,et al.  A study of the dielectric characteristics of aluminum oxide thin films deposited by spray pyrolysis from Al(acac)3 , 2001 .

[27]  Z. Celik-Butler,et al.  Microbolometers on a flexible substrate for infrared detection , 2004, IEEE Sensors Journal.

[28]  Roman Sobolewski,et al.  Investigation of semiconducting YBaCuO thin films: A new room temperature bolometer , 1996 .

[29]  Seonho Seok,et al.  A study on wafer level vacuum packaging for MEMS devices , 2003 .

[30]  Donald P. Butler,et al.  Uncooled infrared microbolometers on a flexible substrate , 2002 .

[31]  Sherif Sedky,et al.  Characterization and optimization of infrared poly SiGe bolometers , 1999 .

[32]  James F. Shackelford,et al.  The CRC Materials Science And Engineering Handbook , 1991 .

[33]  Jin-Shown Shie,et al.  Characterization and modeling of metal-film microbolometer , 1996 .

[34]  More applications of uncooled microbolometer sensors , 1998, Optics & Photonics.