A low-cost 128x128 uncooled infrared detector array in CMOS process

Eminoglu, Selim
Tanrikulu, Mahmud Yusuf
Akın, Tayfun
This paper discusses the implementation of a low-cost 128 x 128 uncooled infrared microbolometer detector array together with its integrated readout circuit (ROC) using a standard 0.35 mu m n-well CMOS and post-CMOS MEMS processes. The detector array can be created with simple bulk-micromachining processes after the CMOS fabrication, without the need for any complicated lithography or deposition steps. The array detectors are based on suspended p(+)-active/n-well diode microbolometers with a pixel size of 40 mu m x 40 mu m and a fill factor of 44%. The p(+)-active/n-well diode detector has a measured dc responsivity (R) of 4970 V/W and a thermal time constant of 36 ms at 50 mtorr vacuum level. The total measured rms noise of the diode type detector is 0.69 mu V for an 8 kHz bandwidth, resulting in a detectivity (D*) of 9.7 x 10(8) cm . Hz(1/2)/W. The array is scanned by an integrated 32-channel parallel ROC including low-noise differential preamplifiers with an electrical bandwidth of 8 kHz. The 128 x 128 focal plane array (FPA) has one row of infrared-blind reference detectors that reduces the effect of FPA fixed pattern noise and variations in the operating temperature relaxing the requirements for the temperature stabilization. Including the noise of the reference and array detectors together with the ROC noise, the fabricated 128 x 128 FPA has an expected noise equivalent temperature difference (NETD) value of 1 K for f/1 optics at 30 frames/s (fps) scanning rate. This NETD value can be decreased to 350 mK by improving the post-CMOS fabrication steps and increasing the number of readout channels.


An uncooled microbolometer infrared focal plane array in standard CMOS
Tezcan, Ds; Eminoglu, S; Akar, Os; Akın, Tayfun (2001-01-24)
This paper reports implementation of a low-cost microbolometer focal plane array using n-well layer in a CMOS process as the microbolometer material. N-well microbolometer structures are suspended for thermal isolation by postetching of fabricated CMOS dies using silicon bulk-micromachining techniques. Although n-well has a moderate TCR of 0.5-0.65 %/K at 300 K, it still provides a reasonable performance due to its single crystal structure which contributes low 1/f noise. Detailed thermal simulations in ANS...
A CMOS n-well microbolometer FPA with temperature coefficient enhancement circuitry
Eminoglu, S; Tezcan, DS; Akın, Tayfun (2001-04-20)
This paper reports the development of a low-cost CMOS microbolometer focal plane array with a new temperature coefficient enhancement readout circuit. We have recently reported an uncooled microbolometer detector that uses the CMOS n-well layer as the active material, where the suspended and thermally isolated n-well structure is obtained by silicon bulk micromachining of fabricated CMOS dies. In addition, we have successfully fabricated a 16x16 n-well microbolometer FPA. Although n-well is single crystal s...
A low-cost small pixel uncooled infrared detector for large focal plane arrays using a standard CMOS process
Eminoglu, S; Tanrikulu, MY; Tezcan, DS; Akın, Tayfun (2002-04-03)
This paper reports the development of a low-cost, small pixel uncooled infrared detector using a standard CMOS process. The detector is based on a suspended and thermally isolated p(+)-active/n-well diode whose forward voltage changes due to an increase in the pixel temperature with absorbed infrared radiation. The detector is obtained with simple post-CMOS etching steps on dies fabricated using a standard n-well CMOS process. The post-CMOS process steps are achieved without needing any deposition or lithog...
Low-cost uncooled infrared detector arrays in standard CMOS
Eminoglu, S; Tanrikulu, MY; Akın, Tayfun (2003-04-25)
This paper reports the development of a low-cost 128 x 128 uncooled infrared focal plane array (FPA) based on suspended and thermally isolated CMOS p(+)-active/n-well diodes. The FPA is fabricated using a standard 0.35 mum CMOS process followed by simple post-CMOS bulk micromachining that does not require any critical lithography or complicated deposition steps; and therefore, the cost of the uncooled FPA is almost equal to the cost of the CMOS chip. The post-CMOS fabrication steps include an RIE etching to...
A CMOS visible image sensor array using current mirroring integration readout circuitry
Akbay, Selim Sermet; Bircan, A.; Akın, Tayfun (null; 2000-08-30)
This paper reports the development of a CMOS visible sensor array using a high performance readout circuit called Current Mirroring Integration (CMI). The sensor element is a photodiode implemented using n-well and p+ -active layers available in any CMOS process. The current generated by optical excitation is mirrored and integrated in an off-pixel capacitor using the CMI readout circuit, which provides high injection efficiency, low input impedance, almost-zero and stable detector bias, and a high dynamic ...
Citation Formats
S. Eminoglu, M. Y. Tanrikulu, and T. Akın, “A low-cost 128x128 uncooled infrared detector array in CMOS process,” JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, pp. 20–30, 2008, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/42245.