A low cost uncooled infrared microbolometer focal plane array using the CMOS n-well layer

Tezcan, DS
Eminoglu, S
Akar, OS
Akın, Tayfun
This paper reports a low-cost, 256-pixel uncooled infrared microbolometer focal plane array (FPA) implemented using a 0.8 mum CMOS process where the n-well layer is used as the active microbolometer material. The suspended n-well structure is obtained by simple front-end bulk etching of the fabricated CMOS dies, while the n-well region is protected from etching by electrochemical etch-stop technique within a TMAH solution. Electrical connections to the suspended n-well are obtained with polysilicon interconnect layer instead of aluminum to increase the thermal isolation of the pixel by an order of magnitude. Since polysilicon has very low TCR and high resistance, the effective TCR of the pixel is reduced to 0.34%/K, even though the n-well TCR is measured to be 0.58%/K A 16x16 pixel array prototype with 80 mu mx80 mum pixel sizes has successfully been implemented. The pixel resistance measurements show that pixels are very uniform with a nonuniformity of 1.23%. Measurements and calculations show that the detector and the array provide a responsivity of 1200V/W, a detectivity of 2.2x10(8)cmHz(1/2)/W, and a noise equivalent temperature difference (NETD) of 200mK at 0.5Hz frame Tate with fully serial readout scheme. This performance can be further increased by using other advanced readout techniques, therefore, the CMOS n-well microbolometer approach seems to be a very cost-effective method to produce large focal plane arrays for low-cost infrared imaging applications.


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 low-cost uncooled infrared microbolometer detector in standard CMOS technology
Tezcan, DS; Eminoglu, S; Akın, Tayfun (Institute of Electrical and Electronics Engineers (IEEE), 2003-02-01)
This paper reports the development of a low-cost uncooled infrared microbolometer detector using a commercial 0.8 mum CMOS process, where the CMOS n-well layer is used as the infrared sensitive material. The n-well is suspended by front-end bulk-micromachining of the fabricated CMOS dies using electrochemical etch-stop technique in TMAH. Since this approach does not require any lithography or infrared sensitive material deposition after CMOS fabrication, the detector cost is almost equal to the CMOS chip co...
A low-power robust humidity sensor in a standard CMOS process
Okcan, Burak; Akın, Tayfun (2007-11-01)
This paper presents a low-cost thermal-conductivity-based humidity sensor implemented using a 0.6-mu m CMOS process, where suspended p-n junction diodes are used as the humidity-sensitive elements. The measurement method uses the difference between the thermal conductivities of air and water vapor at high temperatures by comparing the output voltages of two hea ted and thermally isolated diodes; one of which is exposed to the environment and has a humidity-dependent thermal conductance, while the other is s...
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 64x64 uncooled infrared detector array in standard CMOS
Eminoglu, S; Tanrikulu, MY; Akın, Tayfun (2003-06-12)
This paper reports the development of a low-cost, 64 x 64 uncooled infrared focal plane array (FPA) based on suspended and thermally isolated p(+)-active/n-well diodes in a standard 0.35 mum CMOS process. The array is implemented using a simple post-CMOS process that do not require any critical lithography or complicated deposition steps. The pixel is 40 mum x 40 mum in size with a fill factor of 44%, and it has a measured DC responsivity of 4970 V/W with a thermal time constant of 36 msec at 80 mToff vacuu...
Citation Formats
D. Tezcan, S. Eminoglu, O. Akar, and T. Akın, “A low cost uncooled infrared microbolometer focal plane array using the CMOS n-well layer,” 2001, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/41883.