Numerical simulations of sputter deposition and etching in trenches using the level set technique

We have performed 2D and quasi-3D numerical simulations of physical vapor deposition (PVD) into high aspect ratio trenches used for modern VLSI interconnects. The topographic evolution is modeled using (continuum) level set methods. The level set approach is a powerful mathematical/computational technique for accurately tracking moving interfaces or boundaries, where the advancing front is embedded as the tao level set (isosurface) of a higher dimensional mathematical function. The technique can be equally well applied to etching, including the incorporation of complex mask shapes. First, we study 2D cases for long rectangular trenches including the quasi-3D case in which the 3D target flux is mathematically reduced to an equivalent 2D flux. The 3D flux is obtained from molecular dynamics computations for Al(100), and hence our approach represents a hybrid atomistic/continuum model. We obtain good agreement with X-TEM data. Finally, we present results for etching problems of relevance to shallow trench isolation in electronic devices.