Aiqing Ni (axn37@po.cwru.edu)

and

Roberto Ballarini (rxb7@pop.cwru.edu)

Department of Civil Engineering

Case Western Reserve University

Cleveland, Ohio 44106-7201

Processing procedures for microelectromechanical systems devices result in relatively high residual stresses, and in turn to unwanted shape changes. One way of eliminating the residual stresses is annealing. At CWRU a clever fabrication procedure has been developed to eliminate unwanted shape changes in polycrystalline silicon devices. This Multi-Poly^c approach relies on the fact that at certain temperatures the residual stress is compressive, while at other temperatures the residual stress is tensile. By exploiting the inherent tensile and compressive residual stresses in an alternating design, as-deposited near-zero overall film stresses and near-zero residual stress gradients are achieved. A similar approach is now being pursued for polycrystalline silicon carbide.