3D simulation of sputter deposition of titanium layers in contact holes with high aspect ratios2

A 3D simulation program has been developed which is capable of simulating layer deposition on 3D topography features such as high aspect ratio contact holes. In this paper we investigate the sputter deposition of Ti which, after rapid thermal nitridation (RTN), serves as a barrier layer for subsequent contact hole filling. The low bottom coverage of the sputter deposited layers in contact holes is well predicted by the simulations. Simulations were carried out for a range of different contact hole aspect ratios and good agreement with measured bottom coverage data available from literature was obtained. As the bottom coverage values are essential for assessing the electrical properties of the contact after filling by blanket tungsten, the simulations are very useful for investigating different shapes of contact holes and vias. The simulator is part of a multidimensional process simulation system and part of a topography simulator for optical lithography, dry-etching, and layer depositi on. A result of the simulation of a topography process sequence, leading to a tungsten plug in a contact hole is shown.