Mechanical property measurement of nano-scale metal films on the novel paddle cantilever beams using four step phase-shifting method

A test structure with nano-scale metal films, which is deposited on the novel paddle-like cantilever beam, was successfully fabricated and calibrated using standard C-MOS processes. Compared to the traditional cantilevered beam, the 40 mum thickness paddle-like structure provides the uniform stress distribution along the whole beam to decrease the measurement variation. The deflections of argentums, gold, and copper films (50-250 nm) driven by the electrostatic force were measured using four step phase-shifting method. The results present that the test structure and the optical (FSPS) method work properly. Furthermore, argentums presents that the deflection decreases after deposition to demonstrate that the tensile residual stress in the film. Oppositely, gold and copper films show compressive residual stress in them.