The effect of residual stresses on the deformation of semi-circular micromachined beams

In this research, a semi-circular micromachined beam is proposed in order t o reduce the out-of-plane deformation caused by the residual stresses. The side view of the semi-circular beam is similar to that of a cantilever, whe reas the end conditions are similar to those of the microbridge. Although t he micromachined cantilever will not be deformed by the residual mean stres s, it is significantly bent by the residual gradient stress. On the other h and. the microbridge will not be bent by the gradient residual stress, but is buckled by the mean compression. Analytical and experimental results dem onstrate that the out-of-plane deformation due to bending and buckling is s ignificantly reduced for the semi-circular micromachined beam. Thus, the fl atness of the micromachined suspensions is improved. The more traditional t echniques in which the out-of-plane deformation is reduced, by lowering the net residual stresses of thin films, can be supplemented by the use of the semi-circular micromachined beam.