Encapsulated thermopile detector array for IR microspectrometer

Encapsulated thermopile detector array for IR microspectrometer

Wu, H.
Emadi, A.
De Graaf, G.
Wolffenbuttel, R.F.

Electrical Engineering, Mathematics and Computer Science

Department of ME/EI

2010-04-21

The miniaturized IR spectrometer discussed in this paper is comprised of: slit, planar imaging diffraction grating and Thermo-Electric (TE) detector array, which is fabricated using CMOS compatible MEMS technology. The resolving power is maximized by spacing the TE elements at an as narrow as possible pitch, which is limited by processing constraints. The large aspect ratio of the TE elements implies a large cross-sectional area between adjacent elements within the array and results in a relatively large lateral heat exchange between micromachined elements by thermal diffusion. This thermal cross-talk is about 10% in case of a gap spacing of 10 ?m between elements. Therefore, the detector array should be packaged (and operated) in vacuum in order to reduce the cross-talk due to the air conduction through the gap. Thin film packaging is a solution to achieve an operating air pressure at1.3 mBar, which reduces the cross-talk to 0.4%. An absorber based on an optical interference filter design is also designed and fabricated as an IC compatible post-process on top the detector array. The combination of the use of CMOS compatible materials and processing with high absorbance in 1.5 - 5 ?m wavelength range makes a complete on-chip microspectrometer possible.

microspectrometer
thermopile
IR detector array
interference IR absorber

http://resolver.tudelft.nl/uuid:e88a5727-03d5-4695-9dbd-931724a1801a

SPIE

0277-786X

Proceedings of SPIE, 2010, vol. 7680

Institutional Repository

conference paper

(c)2010 Wu, H., Emadi, A., De Graaf, G., Wolffenbuttel, R.F.