Opportunity at National Institute of Standards and Technology (NIST)
Residual Stress in Electrodeposited Thin Films
Material Measurement Laboratory, Materials Science and Engineering Division
Please note: This Agency only participates in the February and August reviews.
|Stafford, Gery R.
Metallic thin films formed by a number of deposition processes often develop sizable intrinsic stress. Residual elastic stress can drive post-deposition transformations such as whisker growth on the surface of thin films. Stress values that exceed the yield stress of the bulk deposit have also been implicated in the failure of thin films in microelectronic devices. Under some circumstances, complete delamination of the film from its substrate can result. Consequently, understanding the source of this stress is of some technological importance. Aside from any bulk lattice mismatch between the film and substrate, sources of stress in electrodeposited thin films include surface driven lattice parameter compression in individual nuclei, grain boundary formation when nuclei impinge, hydrogen evolution, precipitation of particles with molar volume different than the matrix, and incorporation of additives. Even when deposited on substrates of the same material, electrodeposits thicker than 100 nm typically have a residual compressive in-plane stress for reasons that are not entirely clear. This research will focus on in situ stress measurements, using wafer curvature techniques during the earliest stages of metal deposition from aqueous electrolytes.
Elastic strain; Electrodeposition; Growth stress; Misfit stress; Surface stress; Underpotential deposition; Wafer curvature;
Open to U.S. citizens
Open to Postdoctoral applicants