Integration of a High Temperature Transition Metal Oxide NTC Thin Film in a Microbolometer for LWIR Detection

In this paper, we report the integration of a non-CMOS transition metal oxide composite thin film with a high negative temperature coefficient resistance (NTCR) of 3.8 %/K on a silicon nitride membrane for uncooled infrared microbolometer working in the long wavelength infrared (LWIR) region. The NTC thin film is fabricated by a chemical solution deposition process requiring high crystallization temperature (>750°C). Different micromachined silicon-nitride membrane-supported bolometers (1, 2×2 and 4×4 pixels) with a 170×170 µm
²
pixel size are successfully fabricated and packaged in a vacuum-shielded TO housing. The fabricated devices exhibit a typical noise equivalent temperature difference (NETD) value down to 15 mK×Hz
^-1/2
and a high specific detectivity characteristic of 1.4×10
⁸
cm×Hz
^1/2
×W
^-1
.