3D SIMULATION OF TUNGSTEN LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION IN CONTACT HOLES

We present a new method for three-dimensional (3D) simulation of low-pressure chemical vapor deposition in arbitrary geometries using a segment-based topography discretization with triangles combined with the calculation of particle fluxes to the wafer surface. The simulation program is applied to tungsten LPCVD using the reduction of tungsten hexafluoride (WF6) by silane (SiH4). We found that an approach in which the redistribution of the SiH4 molecules is simulated and a constant reaction probability after collision of a SiH4 molecule with the surface is assumed allows the simulation of this process with a reaction probability which is consistent with thermodynamic calculations. A comparison between a simulated 3D profile and experimental data from tungsten LPCVD in a contact hole shows very good agreement between experiment and simulation.