Platinum based metal layer systems for high temperature SAW sensor devices on langasite

Inhalt:
Surface acoustic wave (SAW) devices are passive and operate up to elevated temperatures where semiconductor based devices fail. Additionally, SAW devices can be interrogated with radio frequency (RF) signals of very low power. For both reasons SAW devices are used as wireless RF sensors in harsh environments. At temperatures above 450deg C, the conventional metallization materials, mainly based on Al, degrade too fast and cannot be used. Published metallization films based on Pt are stable at high temperatures of 800deg C but they contain rare elements like Rh and have not been characterized at high frequencies yet. The aim of this work was to develop a high temperature stable metallization based on easy available elements and investigate their applicability for readout at frequencies like in the ISM band at 433 MHz.