Grain-boundary grooving and agglomeration of alloy thin films with a slow-diffusing species

We present a general phase-field model for grain-boundary grooving and agglomeration of polycrystalline alloy thin films. In particular, we study the effects of slow-diffusing species on grooving rate. As the groove grows, the slow species becomes concentrated near the groove tip so that further grooving is limited by the rate at which it diffuses away from the tip. At early times the dominant diffusion path is along the boundary, while at late times it is parallel to the substrate. This change in path strongly affects the time-dependence of grain boundary grooving and increases the time to agglomeration. The present model provides a tool for agglomeration-resistant thin film alloy design. keywords: phase-field, thermal grooving, diffusion, kinetics, metal silicidesComment: 4 pages, 6 figure

Shadowing effects on the microstructure of obliquely deposited films

Two spatial dimension front tracking simulations have been performed to study the growth of polycrystalline, faceted films from randomly oriented nuclei by varying the deposition angle of the incident flux during physical vapor deposition. The orientation of grain columns, the porosity, the crystallographic texture, and grain size are sensitive to the deposition angle. The origin of this effect is widely believed to be associated with shadowing. In order to isolate the effects of shadowing from other physical effects (such as surface diffusion, deposition species size, flux divergence, etc.), we have constructed a simulation where all of these effects are completely removed. These simulations demonstrate that while many of the observed structural properties of obliquely deposited films are controlled by shadowing, a few key properties cannot be attributed solely to shadowing. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71123/2/JAPIAU-91-4-1963-1.pd