Fabrication of antenna-coupled microbolometers

Fabrication conditions of antenna-coupled microbolometers which function in the far-infrared (FIR) frequency region are discussed. A bow-tie antenna-coupled microbolometer was fabricated on a 300 nm Si3N4 membrane, and detection experiments for 118 mu m CH3OH laser radiation were performed. The measured antenna pattern indicated that the fabricated device functions as an antenna-coupled device which receives the laser radiation by means of the antenna and detects its power by means of the microbolometer. The responsivity of the microbolometer for 118 mu m CH3OH laser radiation was 56 V/W at the bias current of 0.6 mA. Although this value was 1 dB less than that of DC responsivity, we obtained conclusive evidence that the fabricated bismuth microbolometer can be utilized as a detector for a FIR receiving antenna.