Modeling of thermal conductance in an uncooled microbolometer pixel

Topaloglu, Nezih; Nieva, P.; Yavuz, Mustafa; Huissoon, Jan P.

doi:10.1016/j.sna.2009.11.018

Cited by 18 publications

(13 citation statements)

References 12 publications

(18 reference statements)

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“…As briefly mentioned earlier, G ef f consists of a number of components [17], one of which is a thermal conductance component attributed to heat loss between the suspended membrane and the substrate via the support beams, referred to as the beam or leg thermal conductance, G leg and is given by [13,23] It has also recently been proposed to include the constriction resistance that results when two thermal conducting paths of different widths are connected, which leads to a constriction effect experienced by the heat flow. This results in an additional radial thermal resistive component [13,24,25].…”

Section: Operating Principles Of Microbolometersmentioning

confidence: 99%

“…This results in an additional radial thermal resistive component [13,24,25]. The thermal conductivity can be modified to include for the radial thermal conductive component, with the transformed thermal conductivity given by [24] …”

Section: Operating Principles Of Microbolometersmentioning

confidence: 99%

“…Some of the recent advances include analytic models that not only considers the dimensions of the support beams as conventionally done, but also the influence of the device plate that causes a radial heat flow component and constriction resistance resulting from a discontinuity in width when the beam and plate are connected [13]. This model is limited to the beam thermal conductance that dominates device behaviour under vacuum conditions.…”

Section: Introductionmentioning

confidence: 99%

“…It should be highlighted that the presented method can also be applied to microbolometers with any detector material where the resistivity is significantly higher than that of the metal used on the support beam to connect to the detector material, but only at atmospheric pressure. The technique does not apply to vacuum conditions where a constriction type model offers better results [13], nor to metal type microbolometers like thin-film Ti based devices, where an extended surface area method including a portion of the support beams provide the best results [20]. In the sections to follow, the authors will present the theoretical background and proposed improvement to the conventional analytic model, the device designs manufactured for this study, the approaches followed for both the simulation and experimental methods, the results and discussion and finally the conclusion and acknowledgements.…”

Section: Introductionmentioning

confidence: 99%

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An analytic model employing an elliptical surface area to determine the gaseous thermal conductance of uncooled VOx microbolometers

Schoeman

Plessis

2016

Sensors and Actuators A: Physical

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This work presents a detailed overview of the analytic methods for calculating the beam and gaseous thermal conductance components associated with uncooled VO x microbolometers. The conventional method to calculate the gaseous component relies on the assumption that the entire plate is maintained at a uniform temperature, thus the surface area of the plate is used for the calculation. We have observed using an industry leading multiphysics simulator that this assumption is not strictly true for VO x microbolometers as the conduction pattern exhibits an elliptical shape. Based on this, we have developed and propose an analytic method that employs an elliptical surface area scaled appropriately with the device dimensions to obtain an estimate of the average temperature conduction pattern. Prototype devices were manufactured and experimentally characterised. The devices exhibit thermal conduction characteristics comparable to those in literature and industry, and we could achieve 0.5 µW/K under vacuum conditions and 15 µW/K at atmospheric pressure with a TCR of −1 %/K. However, both simulated and experimental result sets of the gaseous thermal conductance exhibit large deviations from the conventional analytic method, on average approximately 40 %. The proposed method reduces this average error significantly to less than 10 % when compared to the simulated results.

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Section: Operating Principles Of Microbolometersmentioning

confidence: 99%

Section: Operating Principles Of Microbolometersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An analytic model employing an elliptical surface area to determine the gaseous thermal conductance of uncooled VOx microbolometers

Schoeman

Plessis

2016

Sensors and Actuators A: Physical

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“…Over the past few years, a lot of attention has been focused on the uncooled IR imaging systems due to their low cost and small size compared with their cooled counterparts. [1][2][3][4][5][6][7][8][9][10][11][12] Uncooled IR sensors have become the technology of choice for low-cost IR imaging systems used in applications such as thermography, firefighting, driver night vision, security and surveillance. Uncooled IR sensors are thermal infrared sensors that absorb electromagnetic radiation and thus increase their temperature.…”

Section: Introductionmentioning

confidence: 99%

Uncooled IR sensor based on lateral polysilicon pn junction diode: initial results

Xiong

Wang

2011

International Symposium on Photoelectronic Detection and Imaging 2011: Sensor and Micromachined Optical Device Technologies

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These days, uncooled IR image sensors utilizing MEMS technologies have been widely studied for night vision and temperature sensing. Compared with other uncooled IR image sensor, uncooled IR image sensor utilizing p-n junction diode detector has merits of good CMOS compatibility, better mass-production, and better detecting uniformity. In this paper, we proposed a novel uncooled IR sensor based on lateral polysilicon p-n junction diode. In the CMOS process, p-type polysilicon is used for PMOS gate electrode material, while n-type polysilicon is used for NMOS gate electrode material. Due to that polysilicon diode is adopted for sensing, the silicon substrate under the microstructure can be completely removed, and a better thermal isolation and a small thermal mass can be achieved. By using the FEM software Ansys, 3D models of the silicon diode and polysilicon diode have been built for thermal simulation. Simulation results verify that a better thermal isolation can be achieved for polysilicon diode. The device was fabricated by standard CMOS process and a XeF 2 post-CMOS maskless dry etching step. Measurement results of the fabricated lateral polysilicon p-n junction diode is also reported.

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Uncooled microbolometer system-level co-simulation using finite element analysis method and intellectual property core

et al. 2016

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Modeling of thermal conductance in an uncooled microbolometer pixel

Cited by 18 publications

References 12 publications

An analytic model employing an elliptical surface area to determine the gaseous thermal conductance of uncooled VOx microbolometers

An analytic model employing an elliptical surface area to determine the gaseous thermal conductance of uncooled VOx microbolometers

Uncooled IR sensor based on lateral polysilicon pn junction diode: initial results

Uncooled microbolometer system-level co-simulation using finite element analysis method and intellectual property core

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