A surface micromachined thermopile detector array with an interference-based absorber

A thermo-electric (TE) infrared detector array composed of 23 thermopiles, each with 5 thermocouples on a suspended beam of 650 × 36 µm2 dimensions, has been fabricated in a CMOS-compatible MEMS process. The array is used for realization of an IR micro-spectrometer in the 1–5 µm spectral range. Interference filter-based IR absorbers using titanium/aluminum layers with a silicon carbide cavity layer have been designed, fabricated and validated. These thin film stacks are more suitable for the subsequent processes as compared to conventional techniques. The silicon carbide layer is also used for device protection. The TE detector with an interference filter-based absorber features a sensitivity of 294 V W−1 in the 2.15 µm wavelength range and a thermal time constant of 4.85 ms in vacuum.