Three-dimensional simulation of conventional and collimated sputter deposition of Ti layers into high aspect ratio contact holes

Three-dimensional (3D) simulations of conventional and collimated sputter deposition of titanium into contact holes with high aspect ratios have been carried out using a 3D topography simulator. In this simulation program the device surface is discretized by a set of triangles. The layer growth rate for each triangle is determined by calculating the flux of metal atoms from the gas volume at the location of the triangle. Shadowing by the device structure itself as well as by a collimator placed between substrate and target is taken into account. For a range of contact hole aspect ratios, bottom coverage resulting from conventional and collimated sputter deposition has been predicted by means of 3D simulations. The simulation results were compared to experimental data and good agreement for both conventional and collimated sputter deposition was found.