Pt-Ni / Pt-Zr electrodes for stable SAW resonator operation during repeated temperature cycling up to 1000°C

This paper reports on novel Pt-Ni / Pt-Zr alloy thin film electrodes for use in high-temperature harsh-environment surface acoustic wave (SAW) devices and sensors. Together with other protective thin film layers, which include capping, adhesion, and interfacial layered structures, the Pt-Ni / Pt-Zr film configuration allowed stable SAW device operation for over 300 hours of thermal cycling and soaking profiles up to 1000°C, and for short terms (12 hours) up to 1100°C. Data reported and discussed in this paper include SAW device impedance measurements obtained after heating up to 1100°C, and sensor frequency response after heating for over 300 hours of measured thermal cycle data between 300°C and 1000°C. The results confirm SAW device stability up to 1000°C for high-temperature harsh-environment sensor and frequency control applications.