Uncooled amorphous silicon technology enhancement for 25-μm pixel pitch achievement

Uncooled Infrared Microbolometer Arrays and their Characterisation Techniques

“…Equation (10) shows that the responsivity is directly proportional to the temperature coefficient of resistance (a) and inversely proportional to the thermal conductance (G) associated with the principal heat loss mechanism. Both parameters are important for uncooled IR resistive bolometers.…”

“…After the development of the technology, the transfer to industrial facilities has been performed in a short period of time and the production is now ramping up with ULIS team in new facilities. LETI and ULIS are now working to facilitate the IR FPA integration into equipment to address a very large market [9][10] . Figure 6 shows the SEM picture and the packaging of the microbolometer IR detector array.…”

“…To improve the sensitivity performance, there are efforts to implement microbolometers using various materials, such as vanadium oxide (VO x ) [5][6][7] , amorphous silicon (a-Si) [8][9][10] , polycrystalline silicon-germanium (poly SiGe) 11,12 , yttrium barium copper oxide (YBaCuO) 13,14 , and metal films 15,26 . A high performance, very close to those of cooled infrared detectors, has been demonstrated with this approach, resulting in focal plane array (FPA) sizes as large as 640 × 480 and pixel sizes ranging from 50 µm down to 17 µm, especially using VOx and a-Si at much lower cost [5][6][7][8][9][10] . Another approach for highly sensitive micorbolometer is the use of silicon p-n junction diodes as the temperature sensitive element instead of resistive microbolometers in the detector arrays [27][28][29] .…”

“…The compatibility of the detectors with CMOS technology, to achieve this integration, is one of the main concerns for the development of lowcost detectors. Implementation of microbolometers on surface micromachined, bridges on CMOS-processed wafers is one of the most common approaches for uncooled IR imaging [5][6][7][8][9][10][11][12] . The bolometers are fabricated on these thermallyisolated and suspended bridges, as shown in Fig.…”

IR region challenges: Photon or thermal detectors? Outlook and means

“…Conventional single-level bolometer arrays typically have the fill factor of 60 to 70% [40,41]. To increase the fill factor, two-layer bolometer design was developed allowing to get it up to 90% [42,43].…”