MODELING BIAS SPUTTER PLANARIZATION OF METAL-FILMS USING A BALLISTIC DEPOSITION SIMULATION

A simulation by ballistic deposition model (SIMBAD) has been developed to predict thin-film microstructures of films deposited over topography. In order to study the radio frequency (rf) bias planarization process, this model has been extended to include film resputtering, redeposition, ion reflection, and ion-induced diffusion. To test the resulting SIMBAD simulations, tungsten was bias sputter deposited over high aspect ratio grooves. The resulting films exhibited increased sidewall coverage and planarity. Ion milling effects were also observed. These features were qualitatively matched by SIMBAD predictions as were microstructural details, such as column orientations and void locations. This preliminary success shows that such SIMBAD simulations can be useful in understanding and optimizing the rf bias planarization process.