Thermopile-type infrared and thermal detectors are used in a number of applications, including infrared spectroscopy, radiometry, security systems, and many consumer products. Although they do not provide vision-quality images as in the case of quantum detectors, thermopiles are still attractive for many low-cost commercial and industrial applications, mainly because they do not need cooling for operation and the technologies are relativly simple.

In this project, we develop a new thermopile structure using n-poly/p+ active layers that are available in any CMOS technology. The thermopile structure is obtained by post-etching of the fabricated and bonded chips. P+ active layers are placed in n-well regions, which are protected from etching by the electrochemical etch-stop technique in a TMAH solution. The n-well regions are then removed using a short EDP etching to reduce the thermal conductivity of the suspended structures, improving the responsivity significantly.

Cross-section illustration of the thermopile structure	SEM view of thermopile structure

APPLICATION AREAS

• Process control
• Remote temperature control
• Security systems

PUBLICATIONS :

[1] Z. Olgun, O. Akar, H. Kulah, and T. Akin, "An Integrated Thermopile Structure with High Responsivity and Detectivity in Any Standard CMOS Technology," Int. Conf. on Solid-State Sensors and Actuators (TRANSDUCERS'97), pp. 1263-1266, Chicago, June 1997. paper.pdf

[2] Z. Olgun, O. Akar, H. Kulah ve T. Akin, "Standart CMOS Teknolojisi ile Üretilebilen Isılküme Tipi Kızılötesi Dedektörler," Elektrik-Elektronik-Bilgisayar Muhendisligi 7. Ulusal Kongresi, s. 75-78, Eylul, 1997 (in Turkish).

[3] T. Akin, Z. Olgun, O. Akar, and H. Kulah, "An Integrated Thermopile Structure with High Responsivity Using Any Standard CMOS Technology," Sensors and Actuators Journal A 66, pp. 218-224, April 1998. paper.pdf

SPONSORED BY

NATO Science for Stability Programme
National Science Foundation