Scaling of piezoelectric in-plane NEMS: Towards nanoscale integration of AlN-based transducer on vertical sidewalls

Abstract

One of the key advantages of Piezoelectric MEMS (PiezoMEMS) is its scalability, overcoming issues commonly associated with alternative transduction methods. However, the breadth and depth of studies on scaling the fabrication process from PiezoMEMS to NEMS (Nano-Electro-Mechanical Systems) remain limited. Effective MEMS miniaturization not only improves energy efficiency and surface area reduction but also enables the coupling of nanoscale physics, particularly Casimir Forces, with the NEMS design, device operation, and fabrication opportunities. Here, combined with the finite element method (FEM) modeling, the experimental aluminum nitride (AlN) nanotransducer fabrication is performed to address the fabrication challenges with beam-based in-plane nanostructures and to develop the piezoelectric NEMS design utilizing a controllable stiction behavior. The FEM modeling demonstrates that the designed structure featuring a 220 nm thick silicon (Si) beam with AlN layers located on vertical sidewalls exhibits controllable jump-to-contact and jump-off-contact behaviors. Based on modeling results, a complete piezoelectric sidewall transducer structure is fabricated. The final transducer represents a patterned Si nanobeam with the Molybdenum-AlN-Aluminum transducer located on the vertical sidewalls. The presented findings not only open new opportunities in the piezoelectric MEMS scaling but also establish a platform for the design of innovative “more-than-a-Moore” devices, such as in-plane mechanical latching switches.

Keywords

• Nanoelectromechanical systems
• Casimir effect
• Aluminum nitride
• Switch
• Transducer
• Scaling