Journal of Sensor Science and Technology (센서학회지)

The Korean Sensors Society (한국센서학회)
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Improved Responsivity of an a-Si-based Micro-bolometer Focal Plane Array with a SiNx Membrane Layer

  • Received : 2022.11.07
  • Accepted : 2022.11.24
  • Published : 2022.11.30
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Abstract

A 12 ㎛ pixel-sized 360 × 240 microbolometer focal plane array (MBFPA) was fabricated using a complementary metaloxide-semiconductor (CMOS)-compatible process. To release the MBFPA membrane, an amorphous carbon layer (ACL) processed at a low temperature (<400 ℃) was deposited as a sacrificial layer. The thermal time constant of the MBFPA was improved by using serpentine legs and controlling the thickness of the SiNx layers at 110, 130, and 150 nm on the membrane, with response times of 6.13, 6.28, and 7.48 msec, respectively. Boron-doped amorphous Si (a-Si), which exhibits a high-temperature coefficient of resistance (TCR) and CMOS compatibility, was deposited on top of the membrane as an IR absorption layer to provide heat energy transformation. The structural stability of the thin SiNx membrane and serpentine legs was observed using field-emission scanning electron microscopy (FE-SEM). The fabrication yield was evaluated by measuring the resistance of a representative pixel in the array, which was in the range of 0.8-1.2 Mohm (as designed). The yields for SiNx thicknesses of SiNx at 110, 130, and 150 nm were 75, 86, and 86%, respectively.

Keywords

Acknowledgement

This work was supported by the Nanomedical Devices Development Project of NNFC in 2022 (No. 1711160154) and by a National Research Council of Science & Technology (NST) grant (No. CRC-19-02-ETRI) funded by the Ministry of Science and ICT of Korea.

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