Quantitative Piezoresponse Force Microscopy of Scandium-Doped Aluminum Nitride using the Cypher IDS AFM, with Applications to Acoustic Resonator RF Filters

Acoustic resonator filters used in wireless communications incorporate a piezoelectric film, often aluminum nitride (AlN), to form an electromechanical resonator. Doping AlN with scandium can increase its piezoelectric response and improve filter performance. However, at high scandium concentrations, defects occur in the films and therefore processing conditions must be optimized. Here, we describe a new atomic force microscope design with interferometric sensing of cantilever displacement that enables quantitative piezoresponse force microscopy. This can assist in optimizing film processing conditions by providing a quantitative measure of piezoelectric response that can be directly correlated with observation of grain structure and film defects.

Read the application note to learn about these topics:

• Introduction to acoustic resonator filters (SAW, BAW, SMR, FBAR)
• The promises and challenges associated with Sc-doped AlN
• Introduction to Piezoresponse force microscopy (PFM)
• How the Cypher IDS enables quantitative PFM measurements
• Results demonstrating quantitative nanoscale PFM measurements on Sc-doped AlN correlated with grain structure and defects
• How Cypher IDS has reproduced key findings about the Sc concentration dependence of AlN piezoelectric response

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