A fabrication study of surface acoustic wave devices for magnetic field detection

Surface acoustic wave (SAW) sensors are versatile devices that can be configured to sense a variety of measurands such as temperature and pressure. The potential use of surface acoustic wave devices for magnetic field detection is explored in this study. Compared to current magnetic field sensors, a sensor based on a SAW delay-line could theoretically achieve a substantially higher sensitivity. In addition to this, such a device could potentially be interrogated wirelessly and act passively consuming no power, opening the doors for numerous application possibilities.\ud A proposed basic design for a SAW magnetic wave sensor is presented along with a fabrication process to manufacture such a device. Using a common SAW delay-line as the basis of the design, material and component selection is justified. A lithium niobate piezoelectric substrate is used as the foundation of the device, with the interdigital transducers fabricated with aluminum. The stimulus-detecting component of the device is a magnetostrictive nickel thin film. A standard microelectronic fabrication process flow was designed and implemented in creating prototype devices using the materials and components described. The fabricated devices are described and issues arising from fabrications are also discussed