On the mass sensitivity of Rayleigh surface acoustic wave (RSAW) resonators

• Published in: 2017 40th International Spring Seminar on Electronics Technology (ISSE) pp. 1 - 6
• Main Authors: Avramov, Ivan D., Stahl, Ullrich
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01-05-2017
• Subjects: Coatings; Polymers; Resonant frequency; Sensitivity; Sensors; Surface treatment
• ISSN: 2161-2536
• DOI: 10.1109/ISSE.2017.8000982

We provide and discuss experimental data on the mass sensitivity of Rayleigh surface acoustic wave (RSAW) two-port resonators (TPR) as an alternative to the quartz crystal microbalance (QCM) for thickness measurements and characterization of extremely thin dielectric layers - in the sub nm to a few tens of nm range where a QCM does not provide sufficient sensitivity. The calibration process is performed in a CVD reactor with precisely controlled coatings of Parylene C - a polymer that is deposited onto the TPR surface at room temperature in the absence of strong electromagnetic fields. Thus the SAW device and the equipment measuring its frequency response online are protected in the process of deposition. The RSAW TPR demonstrates more than 4000 times higher relative sensitivity and up to 180 times lower detection limit than a classical 5 MHz QCM.