Metallic NEMS components fabricated from nanocomposite Al–Mo films

Abstract

We have fabricated fully released nano-electro-mechanical system (NEMS) cantilevers of various geometries from metallic alloy nanocomposite films. At thicknesses of 4.3 and 20.0 nm, these are the thinnest released metal cantilevers reported in the literature to date. Such device dimensions are very difficult to achieve using conventional metal films. We were able to overcome this limitation by using room-temperature co-sputtering to synthesize nanocomposite alloy films of Al–Mo. A systematic investigation of microstructure and properties as a function of Mo content resulted in an optimum film composition of Al–32 at.%Mo with a unique microstructure comprising a dense distribution of nano-scale Mo crystallites dispersed in an amorphous Al-rich matrix. These films were found to exhibit unusually high nanoindentation hardness and a very significant reduction in roughness compared with pure Al, while maintaining resistivity in the metallic range. A single-anchored cantilever 5 µm long, 800 nm wide and 20 nm thick showed a resonance frequency of 608 kHz, yielding a Young’s modulus of 112 GPa, in good agreement with a reduced modulus of 138 GPa measured by nanoindentation.

Resonance properties and microstructure of ultracompliant metallic nanoelectromechanical systems resonators synthesized from Al–32at.%Mo amorphous-nanocrystalline metallic composites

“…This yields a Young's modulus of E = 147 GPa for the cantilevers, in agreement with the nanoindentation analysis which gave a value of 120 GPa. 5 The extreme aspect ratio of these cantilevers makes them very elastically compliant. For a single-clamped cantilever, the spring constant K may be approximated by Eq.…”

“…The only variation from Ref. 5 was an improved sputtering base pressure for the film deposition, which in this study is 2 ϫ 10 −7 Torr. The tested devices have a thickness of 20 nm, a width of 800 nm, and length ranging from 1 to 8 m. The cantilevers also possess a 1.2 m undercut.…”

“…[1][2][3][4] Such microstructures should be well suited for cantilever-based NEMS applications offering a combination of smoothness, strength, and elastic properties. In a previous study, 5 we used room temperature magnetron cosputtering to create Al-Mo films of various compositions. We then tested the films' mechanical and electrical properties, ascertained the surface roughness, and performed some characterization of the microstructure, all as a function of alloy content.…”

“…% Mo thin films and single-clamped NEMS cantilever devices were synthesized and characterized in a manner described in Ref. 5. The only variation from Ref.…”

Buckling of Functionally Graded Nanobeams Based on the Nonlocal New First-Order Shear Deformation Beam Theory

“…During the past decade, FGMs have been widely used in various aspects of engineering sciences, such as aerospace, nuclear, civil, automotive, optical, biomechanical, electronic, chemical, mechanical, and shipbuilding industries. With the development of the material technology, FGMs have been employed in micro/nano-electro-mechanical system (MEMS/NEMS) [2]. Stability studies of nanostructure made of functionally graded materials are of great significance for estimating the performance of FG nanobeams.…”