STRESS GRADIENTS IN ELECTRODEPOSITED Ni MEMS

摘要

Recent attempts to fabricate free-standing MEMS structures using electrodeposited Ni have run into difficulty due to the curvatures that result from stress gradients intrinsic to electrodeposition. We have investigated the intrinsic stress behavior during electrodeposition of Ni from an additive-free sulfamate bath. It was determined that the stress during the first 1000 A of growth was dependent only on the substrate materials, whereas the stress after that point was dependent on the deposition rate. Additionally, the stress in this region was found to be independent of the stress-state of the underlying material. Therefore, by varying the plating dynamically during deposition it is possible to reduce or eliminate the curvature in Ni MEMS structures.