Deposition and simulation of refractory barriers into high aspect ratio re-entrant features using directional sputtering

In this paper three unique facts are demonstrated for the first time: (1) it is possible to deposit by directional sputtering refractory barrier layers such as Ti, TiN and W over re-entrant VLSI topography with aspect ratios greater then 6; (2) variation of the film microstructure down the via occurs and can be verified by simulations; (3) simulation of the microstructure and profile of the deposited film can be used to determine the physics of the redeposition of material on the undercut regions. Using simulations it is determined that the most likely source of the re-emission is resputtering due to neutral bombardment.