A series of surface micromachined microelectromechanical system switches with composite metal beams 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 mum thick evaporated Au film was the basis for all bridge materials with additional 20 nm layers of evaporated or sputter deposited Ti, Pt, W, 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 by optical interferometry. Gold-only bridge structures displayed the best planarity of those examined while structures with Ti layers displayed the least planarity. Cantilever stress gradients calculated using both cantilever-tip deflection and radius of curvature techniques were typically between 9 and 16 MPa/mum. The thin film biaxial moduli used in stress gradient calculations were measured using a wafer curvature technique and were slightly higher than the bulk Au value. Results of this study show that thin metal layers (2%-6% of total beam thickness) have substantial influence on released beam curvatures but that beam planarity can be achieved with a suitable combination of materials. (C) 2003 American Vacuum Society.