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Sensors and Actuators A 109 (2003) 102113 Low-cost uncooled infrared detectors in CMOS process
 

Summary: Sensors and Actuators A 109 (2003) 102113
Low-cost uncooled infrared detectors in CMOS process
Selim Eminoglu, Deniz Sabuncuoglu Tezcan, M. Yusuf Tanrikulu, Tayfun Akin
Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara 06531, Turkey
Received 19 November 2002; received in revised form 5 August 2003; accepted 20 August 2003
Abstract
This paper reports the implementation and comparison of two low-cost uncooled infrared microbolometer detectors that can be imple-
mented using standard n-well CMOS processes. One type is based on a suspended n-well resistor, which is implemented in a 0.8 m CMOS
process and has a pixel size of 80 m 80 m with a fill factor of 13%; and the other type is based on a suspended p+-active/n-well diode,
which is implemented in a 0.35 m CMOS process and has a pixel size of 40 m 40 m with a fill factor of 44%. These detectors can
be obtained with simple bulk-micromachining processes after the CMOS fabrication, without the need for any complicated lithography
or deposition steps. The diode type detector has a measured dc responsivity (R) of 4970 V/W at 20 A bias and a thermal time constant
of 35.8 ms at 80 mTorr vacuum level, and it has a measured rms noise of 0.52 V for a 4 kHz bandwidth, resulting in a detectivity (D)
of 9.7 108 cm Hz1/2/W. The resistive n-well detector can provide the same dc responsivity at 1.68 V detector bias voltage, with about
10 times more self-heating as compared to that of the diode type detector. This detector has a measured rms noise of 0.81 V for a 4 kHz
bandwidth, resulting in a detectivity (D) of 8.9 108 cm Hz1/2/W, which can be improved further with higher detector bias voltages at
the expense of increased self-heating. The diode type detector is better for low-cost large format infrared detector arrays, since it has a
superior response even at reduced pixel sizes and lower biasing levels.
2003 Elsevier B.V. All rights reserved.
Keywords: Uncooled infrared detector; CMOS infrared detector; Microbolometer; Low-cost infrared detector; IR detector; CMOS micromachined sensor

  

Source: Akin, Tayfun - Department of Electrical and Electronics Engineering, Middle East Technical University

 

Collections: Engineering