AVS 49th International Symposium
    Microelectromechanical Systems (MEMS) Wednesday Sessions
       Session MM-WeP

Paper MM-WeP1
Metallization Schemes for RF MEMS Switches

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Poster Session
Presenter: K. Leedy, Air Force Research Laboratory
Authors: K. Leedy, Air Force Research Laboratory
R. Cortez, Air Force Research Laboratory
W. Cowan, Air Force Research Laboratory
J. Ebel, Air Force Research Laboratory
J. McFall, Air Force Research Laboratory
R. Strawser, Air Force Research Laboratory
A. Walker, Air Force Research Laboratory
Correspondent: Click to Email
A series of surface micromachined MEMS switches with composite metal bridges were fabricated by standard photolithographic techniques. The study was conducted in order to assess the influence of film stress and composition on the released shape of cantilever and fixed-fixed beam structures. A 1 µm thick evaporated Au film was the basis for all bridge materials with additional 20 nm layers of evaporated or sputter deposited Ti, Pt, or Au on the top or bottom surface of the thick Au. The planarity and stress gradient of cantilever beam structures and the planarity of fixed-fixed beam structures were measured with optical interferometry. Au-only bridge structures displayed the best planarity of those examined while structures including Ti layers displayed the least planarity. Tensile cantilever stress gradients were calculated using both cantilever tip deflection and radius of curvature techniques. The thin film biaxial moduli used in stress gradient calculations were measured with a wafer curvature technique and were slightly higher than the bulk Au value. Results of this study show that thin metal layers (2% of total beam thickness) have substantial influence on released beam curvatures but that beam planarity can be achieved with a suitable combination of materials.