Microfabrication of lead-free (K, Na)NbO3 piezoelectric thin films by dry etching

In this study, we propose a practical microfabrication method of lead-free sodium potassium niobate [(K, Na)NbO₃, KNN] thin films by dry etching for the first time. We found that Ar/C₄F₈ plasma etching was very effective for high etching rate of KNN thin film as well as excellent selectivity of KNN and Cr metal mask. We successfully fabricated unimorph micro-cantilevers of KNN thin films without process damage and confirmed excellent piezoelectric properties of the microfabricated KNN thin film. These results indicate that Ar/C₄F₈ plasma etching enables to fabricate various lead-free piezoelectric MEMS applications.