Low-cost microbolometer infrared detectors utilizing CMOS resistive layers

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2017
Öztürk, Hande
This thesis presents the efforts to develop low-cost microbolometer type uncooled infrared detector architectures that utilize standard CMOS layers and components. Various resistance structures of different CMOS technologies are investigated and possible resistors are determined as the active material. In order to figure out potential microbolometer structure, all possible layers in the CMOS technologies are analyzed in terms of mechanical and thermal parameters. Mathematical modeling and computer simulations are realized. In order to obtain experimental data about the CMOS components, two different multi-project wafer CMOS chips are completed that contain various resistances and microbolometer structures. These designs are fabricated in a 0.35 µm and 0.18 µm CMOS processes and characterized in terms of electrical resistivity, temperature coefficient of resistance, thermal conductance, and noise. The characterization results are used to employ two different microbolometer infrared sensors focal plane arrays (FPAs), one with the 40x40 array size and 60 µm pixel size and the other one with the 80x80 array size with 35 µm pixel size. The developed and fabricated sensors are characterized in terms of the detector performance successfully. The outcome of this thesis can be summarized in three items. First of all, it is proven that the CMOS resistive layers can be used as the microbolometer active material, thanks to their very low flicker noise and very high uniformity across the FPA. Secondly, the microbolometer architecture designed in the scope of this thesis formed the fundamentals of the CMOS Infrared (CIR) Technology concept, which enables the fabrication of the infrared sensors in almost any CMOS/MEMS foundries in the world. Thirdly, two different infrared pixel structures developed in the scope of this thesis are employed to develop two different microbolometer FPAs with a team effort of Mikrosens Inc. The 40x40 FPA with 60 µm pixel pitch provides an 237 mK NETD value at 30 fps, in a dewar vacuum conditions with f/1 optics, while the 80x80 FPA with 35 µm pixel pitch provides 150 mK and 68 mK NETD values at 17 fps and 4 fps, respectively, in a dewar vacuum conditions with f/1 optics.

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Citation Formats
H. Öztürk, “Low-cost microbolometer infrared detectors utilizing CMOS resistive layers,” M.S. - Master of Science, Middle East Technical University, 2017.