High precision pressure sensors based on SAW devices in the GHz range

• Published in: Sensors and actuators. A. Physical. Vol. 189; pp. 364 - 369
• Main Authors: Rodríguez-Madrid, J.G., Iriarte, G.F., Williams, O.A., Calle, F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2013
• Subjects: Actuators; AlN/free-standing diamond; Aluminum nitride; Deposition; Devices; Diamonds; Frequency ranges; High frequency; Nucleation side; Pressure sensor; Pressure sensors; Resonators; SAW resonators; Sensors; Surface acoustic waves; AlN/free-standing diamond; High frequency; Nucleation side; Pressure sensor; SAW resonators
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2012.09.012

► We deposit AlN on free standing diamond substrates for sensors applications. ► The deposit of AlN on diamond has been optimized for different film thicknesses. ► We have fabricated SAW resonators operating in the 10–14GHz frequency range. ► The devices were used as SAW pressure sensors with a sensibility of 0.33MHz/bar.
In this paper, an AlN/free-standing nanocrystalline diamond (NCD) system is proposed in order to process high frequency surface acoustic wave (SAW) resonators for sensing applications. The main problem of synthetic diamond is its high surface roughness that worsens the sputtered AlN quality and hence the device response. In order to study the feasibility of this structure, AlN films from 150nm up to 1200nm thick have been deposited on free-standing NCD. We have then analysed the influence of the AlN layer thickness on its crystal quality and device response. Optimized thin films of 300nm have been used to fabricate of one-port SAW resonators operating in the 10–14GHz frequency range. A SAW based sensor pressure with a sensibility of 0.33MHz/bar has been fabricated.