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DS: Fachverband Dünne Schichten
DS 16: Layer Properties: Electrical, Optical, and Mechanical
DS 16.10: Talk
Tuesday, March 8, 2016, 12:00–12:15, H11
Reactive magnetron sputtering of stress-controlled piezoelectric AlScN thin films — •Yuan Lu1, Markus Reusch1,2, Tim Christoph1, Vadim Lebedev1, Nicolas Kurz1,2, Lutz Kirste1, Oliver Ambacher1,2, and Agne Zukauskaite1 — 1Fraunhofer Institute for Applied Solid State Physics IAF, Tullastr. 72, 79108 Freiburg, Germany — 2IMTEK, University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany
AlN is a dominant choice for radio frequency microelectromechanical systems (RF-MEMS) used in mobile telecommunications. However, AlN’s relatively low piezoelectric response (d33≈6 pC/N) and electromechanical coupling (kt2≈7%) limit the bandwidth of the frequency filters. It was recently shown that AlScN has 400% higher d33=27.6 pC/N (for Al0.43Sc0.57N) and kt2≈10-15%, making this material a very promising alternative to AlN. In addition to piezoelectric properties, parameters such as film stress need to be controlled to fabricate high performance AlScN-based piezoelectric devices. The aim of this work is to synthesize stress-controlled AlScN thin films suitable for RF-MEMS applications. Reactive RF magnetron sputtering with an Al0.83Sc0.17N alloy target is used to produce 250-1000 nm thick AlScN films on Si(100) substrates. Film stress is investigated by wafer geometry measurements, the clamped d33 is measured by Berlincourt method, and the film quality is evaluated by using X-ray diffraction. Piezoresponse force microscopy is used to confirm the piezoelectric phase uniformity. The growth process optimization leading to the AlScN films with moderate stress values (<500 MPa) will be discussed.