Thermoelectric thick film patterns formed by using thermally-assisted sputtering method and silicone lift-off masks

An increase of film thickness is important for thermoelectric film modules to convert thermal energy into electric energy because the generation power increases with reducing internal resistance of the modules. This article presents a patterning process of thermoelectric thick films using thermally-assisted sputtering method (TASM) and lift-off techniques. Polydimethylsiloxane (PDMS) was used as heat resistant lift-off masks which are needed in TASM. The weight loss of PDMS was as small as 0.5% at 300°C by thermogravimetry analysis. PDMS patterns of lift-off masks with 100 μm height were formed on glass substrates using resist patterns as molds. The substrate temperature reached approximately 300 °C when Bi₂Te₃ thermoelectric thick films were deposited by TASM. After depositing the films, PDMS lift-off masks which were not melted and significantly non-deformed were removed from the substrates. Bi₂Te₃ thick film patterns with 300 μm width and 30 μm height were obtained. This patterning process of thick films can be applied to produce thermoelectric thick film generators with high generation power.