The effect of Ti adhesion layer on the thermoelectric noise of a high resolution thermopile for nanowatt heat flux sensor

Abstract The effect of Ti adhesion layer on the thermoelectric noise of Microelectromechanical system (MEMS) thermopile sensor is investigated in this study. Although the adhesion layer does not affect the thermoelectric voltage through the Seebeck effect, it can influence the thermoelectric noise....
Ausführliche Beschreibung

Abstract The effect of Ti adhesion layer on the thermoelectric noise of Microelectromechanical system (MEMS) thermopile sensor is investigated in this study. Although the adhesion layer does not affect the thermoelectric voltage through the Seebeck effect, it can influence the thermoelectric noise. Two kinds of samples are prepared, both with and without Ti adhesion layers between the contact junctions of thermopile which are patterned with the 30-array of Au and Cr (Gold-chromium). The Ti layer is used to provide adhesion to the gold film. The surface contact resistance is evaluated by the geometric resistance obtained from a FEM model. These experiments show that the adhesion contact thermopile results in total resistance of 32.64 kΩ and noise amplitude of 313 μV, whereas the direct contact thermopile results in 24.49 kΩ and 187 μV, respectively. The surface of the contact junction are inspected with scanning electron microscopy(SEM), and atomic force microscopy(AFM) to investigate how the Ti adhesion layer affects the increment of the surface contact resistance. Furthermore, a heat flux sensor fabricated with the direct contact junctions of the thermopile achieves sensitivity of 62.9 mV/nW and resolution of 1 nW. Ausführliche Beschreibung