This is an NYI award for FY 92. The research will focus on two areas: (1) diffusive voiding in metallizations caused by electromigration and thermal stress, and (2) mechanics of ferroelectric ceramics. The first problem area involves diffusive voiding in metal interconnects in very large-scale integrated (VLSI) circuits. A unified approach to thermal voiding and electromigration will be developed that will establish the explicit dependence of the phenomena on design variables such as material properties, current density, thermal history and interconnect configuration. This will enable the mathematical model so created to be validated by comparison to a variety of experimental results. The second problem area is concerned with deformation, polarization and degradation of ferroelectric ceramics. The research will provide an analytical framework relating the mechanisms of domain wall motion and twinning to macroscopic response between stress, electric field, deformation and polarization of ferroelectric ceramics. This physically-based constitutive relation would be used to study the important phenomena of fatigue cracking under alternating electric fields.
