Simulations of metal thin film thermal flow processes

We use EVFLOW, a thin him thermal flow process simulator, to simulate the thermal flow of metal thin films in axisymmetric contacts/vias on patterned wafers, where two dimensional surface evolution is appropriate. The flow processes considered are (1) Al and Au thin film laser melting processes, for which process temperatures are higher than the metal melting points, and (2) conventional Al thermal anneal processes (400-550 degrees C). Surface tension induced mass transport in the flowing films is calculated by solving the Navier-Stokes and continuity equations for incompressible fluids. Our simulations of Au film profiles during laser melting process predict the experimentally observed trends in void formation and collapse with feature geometry and deposited him thickness. In laser melting processes, the void shrinks and vanishes, resulting in fully filled contacts and planarized metal surfaces. Al film evolution in the thermal anneal process is modeled using a surface layer melting model. The thickness of the liquidlike flowing layer is assumed to be 0.02 mu m in this work. The trends in the formation of voids with feature geometry and deposited him thickness predicted by EVFLOW reflect experimental observations. Voids may form during the thermal anneal processes. The surface layer melting model as used in this work will not predict the collapse of voids. (C) 1996 American Vacuum Society.