Soft-Chemistry-Assisted On-Chip Integration Of Nanostructured Alpha-Quartz Microelectromechanical System

The development of advanced piezoelectric alpha-quartz microelectromechanical system (MEMS) for sensing and precise frequency control applications requires the nanostructuration and on-chip integration of this material on silicon material. However, the current quartz manufacturing methods are based on bonding bulk micromachined crystals on silicon, which limits the size, the performance, the integration cost, and the scalability of quartz microdevices. Here, chemical solution deposition, soft-nanoimprint lithography, and top-down microfabrication processes are combined to develop the first nanostructured epitaxial (100)alpha-quartz/(100)Si piezoelectric cantilevers. The coherent Si/quartz interface and film thinness combined with a controlled nanostructuration on silicon-insulator-silicon technology substrates provide high force and mass sensitivity while preserving the mechanical quality factor of the microelectromechanical systems. This work proves that biocompatible nanostructured epitaxial piezoelectric alpha-quartz-based MEMS on silicon can be engineered at low cost by combining soft-chemistry and top-down lithographic techniques.