| AVS 55th International Symposium & Exhibition | |
| MEMS and NEMS | Tuesday Sessions |
| Session MN-TuM |
| Session: | Materials Processing and Characterization for MEMS/NEMS |
| Presenter: | N. Nelson-Fitzpatrick, University of Alberta, Canada |
| Authors: | N. Nelson-Fitzpatrick, University of Alberta, Canada C. Ophus, University of Alberta, Canada E. Luber, University of Alberta, Canada Z. Lee, Lawrence Berkeley National Laboratory V. Radmilovic, Lawrence Berkeley National Laboratory D. Mitlin, University of Alberta, Canada S. Evoy, University of Alberta, Canada |
| Correspondent: | Click to Email |
Micro and nanomechanical cantilevers and resonators have received significant attention as a technological solution for ultra-sensitive mass detection.1 One promising approach to enable specific nanoresonator-based biosensing would be to coat the devices with a thin film of gold in order to exploit thiol-based chemistries for the functionalization of these surfaces. However, such metal coatings would significantly lower its resonance quality, impairing its mass sensitivity.2 Alternatively, we are currently developing of a novel Au/Ta alloy that would allow the machining of micro and nanomechanical devices directly out of the metal.3 Metals have been largely overlooked as a structural material for NEMS since most deposition methods tend to yield films with large grain structures complicating reliable machining at the nanometer scale, and containing differential stresses which result in the deformation of released devices. To remedy these problems, we must be able to deposit a metal that is either amorphous or has extremely small grain sizes in order to fabricate a device with nm size critical dimensions. Previously we reported on the deposition of Au/Ta nanocomposites for the purpose of making NEMS resonators.3 We reliably realized 50nm thick Au/Ta nanoresonators with low stress (~20MPa), reduced grain size and RMS roughness. The devices also retained the gold’s <111> texture important for the formation of thiolized SAMs. We have now moved on to the development of micro-cantilevers operating in the static regime with this material. The fine grain size of this alloy enables the realization of ultra-thin, ultra-compliant, released cantilevers directly out of Au/Ta composite. The distinctive grain structure of this material, as well as the inclusion of tantalum impacts the dynamics of molecular attachment, which will affect the response of static cantilevers to the target analyte. To that end, we intend to present a full study on the impact of the alloy nanostructure and its composition on the surface stresses induced by the chemical attachment of a thiolized SAM.
1 Ilic B, Czaplewski D, Craighead H G, Neuzil P, Campagnolo C and Batt C, 2000 Appl. Phys. Lett. 77 450
2 Sekaric L, Carr D W, Evoy S, Parpia J M and Craighead H G, 2002 Sens. Act. A 101 215
3 Nelson-Fitzpatrick N, Ophus C, Luber E, Gervais L, Lee Z, Radmilovic V, Mitlin D, and Evoy S, 2007 Nanotechnology 18.