Microcantilevers fabricated by microelectromechanical system processes were used to study the residual stresses in the film/substrate systems. Aluminum films were deposited on silicon nitride substrates by thermal evaporation at room and elevated temperatures, and residual stresses were characterized from the deflection profiles of the Al/SiNx microcantilevers. The Al/SiNx microcantilever beam made of room-temperature-deposited Al film was found to deflect toward the substrate side, which in turn resulted in compressive residual stress in the film. In contrary, the microcantilever of Al film deposited at 105 °C was found to deflect toward the side of Al film when the thickness ratio of film to substrate was greater than 0.31 and the residual film stresses were tensile. The axes with zero bending strain component and zero stresses, i.e., the bending and the neutral axes in the film/substrate system were also investigated. The results can be applied to the arm of the atomic force microscope to characterize its deflection and stresses.