Simulation of uniformity and lifetime effects in collimated sputtering

Collimated sputtering has been successful in providing good contact barriers for sub‐half micron contacts with aspect ratios of 3 and greater. This approach does present drawbacks, however, particularly in terms of reduced deposition rates and degraded film uniformity. The deposition rate can be less than 25% relative to uncollimated systems due to the flux collected on the collimator itself. This in turn leads to closing off of the collimator cells by depositing material, which further reduces deposition rate on the wafer and limits the life of the collimator. This article demonstrates simulation of the filling of the collimator with different system configurations and pressures using the SIMSPUD vapor transport and SIMBAD thin‐film growth simulators. The model can determine collimator filling uniformity, blanket film uniformity, angular distribution of collimated sputter flux, and lifetime of the collimator. Given the target erosion profile, system geometry, and deposition rate, collimator lifetime can ...