Micromachined room-temperature microbolometer for millimeter-wave detection and focal-plane imaging arrays

Arifur Rahman; Erik K. Duerr; Gert de Lange; Qing Hu

doi:10.1117/12.277073

27 June 1997 Micromachined room-temperature microbolometer for millimeter-wave detection and focal-plane imaging arrays

Arifur Rahman, Erik K. Duerr, Gert de Lange, Qing Hu

Proceedings Volume 3064, Passive Millimeter-Wave Imaging Technology; (1997) https://doi.org/10.1117/12.277073
Event: AeroSense '97, 1997, Orlando, FL, United States

Abstract

We have combined silicon micromachining technology with planar circuits to fabricated room-temperature niobium microbolometers for millimeter-wave detection. In this type of detector, a thin niobium film, with a dimension much smaller than the wavelength, is fabricated on a 1-micrometers thick Si₃N₄ membrane of square and cross geometries. The Nb film acts both as a radiation absorber and temperature sensor. Incident radiation is coupled into the microbolometer by a 0.37 (lambda) dipole antenna with a center frequency of 95 GHz and a 3-db bandwidth of 15%, which is impedance matched with the Nb film. The dipole antennas is placed inside a micromachined pyramidal cavity formed by anisotropically etched Si wafers. To increase the Gaussian beam coupling efficiency, a machined square or circular horn is placed in front of the micromachined section. Circular horns interface more easily with die-based manufacturing processes; therefore, we have developed simulation tools that allow us to model circular machined horns. We have fabricated both single element receivers and 3 X 3 focal-plane arrays using uncooled Nb microbolometers. An electrical NEP level of 8.3 X 10^-11 W/(root)Hz has been achieved for a single- element receiver. This NEP level is better than that of the commercial room-temperature pyroelectric millimeter-wave detectors. The frequency response of the microbolometer has a ln(1/f) dependence with frequency, and the roll-off frequency is approximately 35 kHz.

Citation Download Citation

Arifur Rahman, Erik K. Duerr, Gert de Lange, and Qing Hu "Micromachined room-temperature microbolometer for millimeter-wave detection and focal-plane imaging arrays", Proc. SPIE 3064, Passive Millimeter-Wave Imaging Technology, (27 June 1997); https://doi.org/10.1117/12.277073

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