A sub-200 nanometer wide 3D stacking thin-film temperature sensor

Abstract

We developed a series of thin-film thermocouples (TFTCs) made from Cr, Au, and Pd long stripes with a width of 90–300 nm and a 10 nm insulating HfO₂ layer. The sensors have a three-dimensional sandwich structure, therefore reducing the total width down to 138 nm. Their sensitivity (thermopower) values were measured to be 9.6 ± 0.7 μV K⁻¹ for the Cr/HfO₂/Pd sensors and 3.6 ± 0.1 μV K⁻¹ for the Au/HfO₂/Pd sensors. These sensors showed reproducible and reliable measurement performance with a good temperature resolution of 0.04–0.1 K and a small heat capacity of 3.2–3.5 × 10⁻¹⁴ J per K per micron length, making them promising candidates for applications in electronic devices, microfluidic systems, and single cell or sub-cell detection as built-in sensors.