High-temperature stability of LiNbO/sub 3/ based SAW devices

The high temperature stability of SAW (surface acoustic wave) devices based on LiNbO/sub 3/ is investigated in this paper for high temperature applications up to 400/spl deg/ C. Driven by the need for high temperature application based on sophisticated SAW technology, for temperature measurement and identifying a pressure sensor inside of a combustion engine, LiNbO/sub 3/ has been examined, regarding a low cost solution and mass production. Using a high temperature oven and a network analyzer the acoustic attenuation loss and the aging of the devices have been observed. The aging and demolition of substrates and metalizations have been investigated in detail to make an estimation of the economic lifetime. Finally this paper shows the capability of LiNbO/sub 3/ based SAW devices for temporary usage in high-temperature applications.