Science and Technology of Piezoelectric/Diamond Hybrid Heterostructures for High Performance MEMS/NEMS Devices
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1052-DD07-05
Science and Technology of Piezoelectric/Diamond Hybrid Heterostructures for High Performance MEMS/NEMS Devices Orlando Auciello,1,2 Anirudha Sumant,2 Jon Hiller,3 Bernd Kabius,3 and Sudarsan Srinivasan,2 * 1 Materials Science Division, 2Cernter for Nanoscale Materials, 3 Center for Electron Microscopy, Argonne National Laboratory, Argonne, IL 60439 *Now at INTEL ABSTRACT Most current micro/nanoelectromechanical systems (MEMS/NEMS) are based on silicon. However, silicon exhibits relatively poor mechanical/tribological properties, compromising applications to some devices. Diamond films with superior mechanical/tribological properties provide an excellent alternative platform material. Ultrananocrystalline diamond (UNCD®) in film form with 2-5 nm grains exhibits excellent mechanical and tribological properties for highperformance MEMS/NEMS devices. Concurrently, piezoelectric Pb(ZrxTi1-x)O3 (PZT) films provide high sensitivity/low electrical noise for sensing/high-force actuation at relatively low voltages. Therefore, integration of PZT and UNCD films provides a high-performance platform for advanced MEMS/NEMS devices. This paper describes the bases of such integration and demonstration of low voltage piezoactuated hybrid PZT/UNCD cantilevers. INTRODUCTION Most current micro/nanoelectromechanical systems (MEMS/NEMS) are based on silicon. However, the relatively poor mechanical/tribological properties of Si compromise applications to particular devices, specifically those trequiring high Young modulus, such as resonators, and low or no stiction, such as switches. Alternatively, diamond, which exhibits high Young’s modulus and negligible surface adhesion, on contact, can yield high-performance MEMS/NEMS devices, such as resonators and switches. Fabrication of diamond-based devices requires growth of diamond films on appropriate substrates followed by photolithography and etching to release moving structures (e.g., cantilevers, beams). Ultrananocrystalline diamond (UNCD®) developed at Argonne National Laboratory (ANL), exhibits hardness (98 GPa) and Young modulus (980 GPa) close to values for single crystal diamond (100 GPa and 1100 GPa, respectively), extremely low friction coefficient (0.02-0.04) and force of adhesion for surfaces in contact (~ 30mJ/m), smoothest surface morphology (~ 4-7 nm rms roughness), compared to other films with the sp3 bonding structure of single crystal diamond (notice that the comparison is not with diamond-like (DLC) or ta-C films, which exhibit lower roughness than UNCD but also lower hardness and Young modulus than UNCD and other “diamond” films1). In addition, UNCD is currently the only “diamond” film that can be grown at the lowest deposition temperature demonstrated today (~ 400 ˚C), compared with other process producing microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films. DLC films can be deposited at room temperature, but they need to be annealed to >> 400 ˚C to release stresses, which impede,
currently, their integration with CMOS devices for monoli
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