AVS 49th International Symposium
    Microelectromechanical Systems (MEMS) Thursday Sessions
       Session MM+TF-ThM

Invited Paper MM+TF-ThM1
Tetrahedral Amorphous-carbon (ta-C) for MEMS Applications

Thursday, November 7, 2002, 8:20 am, Room C-210

Session: Development and Characterization of MEMS Materials
Presenter: T.A. Friedmann, Sandia National Laboratories
Authors: T.A. Friedmann, Sandia National Laboratories
J.P. Sullivan, Sandia National Laboratories
R.V. Ellis, Sandia National Laboratories
T.M. Alam, Sandia National Laboratories
M.P. de Boer, Sandia National Laboratories
T.E. Buchheit, Sandia National Laboratories
Correspondent: Click to Email
This presentation will focus on ta-C film properties (primarily stress relaxation) and MEMs and sensor devices fabricated from low stress ta-C material (not coatings of Si devices) with an emphasis on mechanical and adhesion property measurements enabled by device fabrication. Pulsed laser deposition (PLD) was used to grow the ta-C films. They can be fully stress relieved by simple thermal annealing without significantly altering the film mechanical properties. Two mechanisms for stress relief in these materials have been postulated, each involving strain-relieving transformations between sp@super 2@ and sp@super 3@ carbon. Recently, we have made fully @super 13@C enriched films by ablating from a @super 13@C (99%) target. NMR magic-angle spinning measur ements of these enriched f ilms have been made to quantify the changes in structure with annealing in an effort to validate the proposed models. Results of these measurements will be presented along with Raman, TEM, and cross-section EELS experiments. The low stresses that are achievable in ta-C enable interesting MEMS and sensor applications. We have demonstrated several one-level MEMS structures from this material (e.g. cantilever beams, microxylophone resonators, fatigue test, tensile test, and membran e based sensors) and used these structures for materials property measurements. Results of selected experiments will be presented. *This work was supported by the U.S. DOE under contract DE-AC04-94AL85000 through the Laboratory Directed Research and Development Program, Sandia National Laboratories.