| Two challenges that arise in multilevel interconnection are deposition of void-free dielectric films into the gaps between metal lines and deposition of interconnection metal films into high aspect ratio vias in dielectric layers, especially when the technology advances to 0.35 ;For better process integration and equipment design, an accurate topography simulator is needed to study the deposition kinetics, to emulate the profile evolution behavior, to understand the void-forming mechanisms, and eventually to help optimize process design by providing guidelines for improving the gap-fill and via-fill performance. In this work basic three-dimensional flux calculation methods for topography simulation are developed on two idealized yet representative structures: the infinitely long trench and the axisymmetric via. Major topics covered in this work include neutral chemical reaction induced deposition, ion induced deposition, ion sheath-transport and angular distribution, surface re-sputtering, re-deposition of sputtered materials, isotropic and anisotropic re-emission, gas phase diffusion (at atmospheric pressure), and geometry-dependent surface reaction. Both the deposition mechanisms and gap-fill (via-fill) performances of these different deposition techniques are compared based on simulation. Procedures are developed to systematically extract the simulation parameters from experimental SEM pictures and to use them for process design by feedback simulation.;A new surface evolution algorithm is developed for this topography simulator under the demand of dealing with singular surface features such as sharp corners, which are usually difficult to treat in the conventional bisector method, without invoking non-physical procedures to smooth the surface. |
