Microbolometer Type Uncooled Infrared Detectors in Standard CMOS Technology

Uncooled infrared detectors have recently gained wide attention for infrared imaging applications, due to their advantages such as low cost, low weight, low power, wide spectral response, and long-term operation compared to those of photon detectors. Microbolometers are most widely used uncooled infrared detectors due to their compatibility with CMOS technology. They can be monolithically integrated with CMOS circuitry which allows their cost to be low.

The application areas of the uncooled detectors can be summarized as:

Military Applications

Civilian Applications

Simple surveillance

Night vision enhancers for drivers

Light weight helmet sights

Fire fighting

Munitions

Handheld camera

Rifle sights

Process control

Unattended ground sensors

Medical imaging

Advanced threat warning

Navigation

Long range scouts

Security systems

Missile seeker

Satellite instruments

In this project we have implemented the lowest-cost uncooled infrared microbolometer, where the CMOS n-well layer is used as the active sensor material. The suspended n-well structure have been obtained by post-etching of the fabricated CMOS dies, while the n-well was protected from etching by the electrochemical etch-stop technique in TMAH.

We have two types of n-well microbolometers. In the first generation n-well microbolometers, the n-well structure is used as a resistor. A 16x16 array was fabricated with this approach. In the second generation microbolometers, n-well is used as a diode in order to increase the performance of the detectors. 16x16, 64x64, and 128x128 detector arrays are fabricated with these detectors. Below you can see some pictures of the fabricated n-well microbolometers.

The main advantage of these detectors is that they can be fabricated in any CMOS technology together with their readout circuits, which makes the cost of the detectors very low. Our research have shown that n-well microbolometers can provide a reasonable performance for low-cost uncooled imaging especially for civil applicaitions.


Resistor type n-well microbolometer from 16x16 array


Single pixel diode type n-well microbolometer (underneath)


Diode type n-well detectors from 128x128 array


Diode type n-well microbolometers from 128x128 array (underneath)


Fabricated Arrays

Publications

1 S. Eminoglu, D. Sabuncuoglu Tezcan, M.Y. Tanrikulu, and T. Akin, "Low-Cost Uncooled Infrared Detectors in CMOS Process," Sensors and Actuators A , Vol. 109/1-2, pp. 102-113, Dec. 2003.
2 D. Sabuncuoglu Tezcan, S. Eminoglu, and T. Akin, "A Low Cost Uncooled Infrared Microbolometer Detector in Standard CMOS Technology," IEEE Trans. on Electron Devices, Vol. 50, No. 2, pp. 494-502, Feb. 2003.
3 S. Eminoglu, M.Y. Tanrikulu, and T. Akin, "Low-Cost 64x64 Uncooled Infrared Detector Arrays in Standard CMOS," The 12th Int. Conf. on Solid-State Sensors and Actuators (TRANSDUCERS'03, Eurosensors XV), pp. 316-319, Boston, Massachusetts, June 8-12, 2003.
4 S. Eminoglu, M.Y. Tanrikulu, and T. Akin, "Low-Cost Uncooled Infrared Detector Arrays in Standard CMOS," SPIE AeroSense Symposium, Infrared Technology and Applications XXIX (Aerosense 2003), SPIE Vol. 5074, pp. 425-436, Orlando, Florida, April 21-25, 2003.
5

S. Eminoglu, D. Sabuncuoglu Tezcan, M.Y. Tanrikulu, and T. Akin, "Low-Cost Uncooled Infrared Detectors in CMOS Process," The 16th European Conf. on Solid-State Transducers (Eurosensors XVI), pp. 480-483, Prague, Czech Republic, September 15-18, 2002.

6 S. Eminoglu, M.Y. Tanrikulu, D. Sabuncuoglu Tezcan, and T. Akin, "A Low-Cost, Small Pixel Uncooled Infrared Detector for Large Focal Plane Arrays using a Standard CMOS Process," SPIE AeroSense Symposium, Infrared Technology and Applications XXVIII (Aerosense 2002), SPIE Vol. 4721, pp. 111-121, Orlando, Florida, April 1-5, 2002.
7 S. Eminoglu, D.S. Tezcan, and T. Akin, "CMOS N-Well Microbolometer FPA with Temperature Coefficient Enhancement Circuitry," SPIE AeroSense Symposium, Infrared Technology and Applications XXVII (Aerosense 2001), SPIE Vol. 4369, pp. 240-249, Orlando, Florida, April 16-20, 2001.
8 D.S. Tezcan, S. Eminoglu, O. S. Akar, and T. Akin, "An Uncooled Microbolometer Infrared Focal Plane Array in Standard CMOS," Photodetector Materials and Devices VI (Opto-electronics 2001), SPIE Vol. 4288, January 20-26, 2001.
9 D.S. Tezcan, S. Eminoglu, O. S. Akar, and T. Akin, "A Low Cost Uncooled Infrared Microbolometer Focal Plane Array Using the CMOS N-Well Layer," The 14th IEEE Int. MicroElectroMechanical Systems Conf. (MEMS 2001), pp. 566-569, Interlaken, Switzerland, January 21-25, 2001.
10 D.S. Tezcan, F. Kocer, and T. Akin, "An Uncooled Microbolometer Infrared Detector in any Standard CMOS Technology," The 10th Int. Conf. on Solid-State Sensors and Actuators (TRANSDUCERS'99), pp. 610-613, Sendai, Japan, June 7-10, 1999.