Suspended Insulation Structure Design for Infrared Thermal Detector

Abstract

Infrared thermal detectors generate signal output utilizing thermal effect, with detection performance being dictated by the structure design of the detector. To ensure effective thermal insulation, detectors are typically designed with slender supporting beams to reduce thermal conductivity and enhance signal output. In this paper, a fluorescent infrared detector with different isolation beam designs is proposed to investigate the trade-off relationship among detector performance parameters. Two kinds of isolation beams are theoretically derived to minimize the thermal conductivity for specific detection unit, and the thermal detectors with suspending units are manufactured by MEMS technology. The thermal imaging results for a 623 K heat source indicate that the temperature rise for the two-beam structure (i.e. 46.7 K) exceeds that of the four-beam structure (i.e. 38.3 K). Additionally, the detectivity of $4.05\times 10^{\mathbf {7}}$ cm $\cdot $ Hz $^{\mathbf {1/2}}$ /W is obtained by the two-beam structure, which is lower than that of the four-beam structure (i.e. $5.80\times 10^{\mathbf {7}}$ cm $\cdot $ Hz $^{\mathbf {1/2}}$ /W). The temporal resolution and NETD are also calculated and compared. The findings demonstrate that in designing thermal detectors, deliberately sacrificing a portion of the detectivity within an acceptable range and reducing beam thermal conductivity can significantly enhance temperature rise and increase signal output. [2024-0131]