Investigation of high-temperature degradation of platinum thin films with an in situ resistance measurement apparatus

Many microfabricated systems require metallizations that can withstand high temperatures. In particular, a microfabricated chemical reactor system which we are investigating needs thin metal films for heating and temperature sensing that can withstand prolonged 1000/spl deg/C exposure. The current microreactor metallization, a 100-nm platinum film with a 10-nm titanium adhesion layer, degrades at temperatures greater than 700/spl deg/C. This degradation was examined with a custom-built high-temperature resistance measurement apparatus in addition to chemical analysis, scanning electron microscopy (SEM), atomic-force microscopy (AFM) and wafer curvature measurements. Thicker films and coating layers increased the lifetime of these films while exposure to oxygen decreased lifetime, consistent with the hypothesized degradation mechanism of agglomeration.