| Next-generation plasma-process modeling tools can provide new insight into process dynamics by resolving the diverse length and time scales present in reactor systems. The length scales range from the size of the reactor ({dollar}sim{dollar}10 cm) to surface details ({dollar}sim{dollar}100 nanometers), and time scales from electron sheath-transit times (ns) to total process time (minutes). Other key features include dynamic coupling of the plasma and solid (particles and fields), and the ability to model realistic surface interactions (deposition, etch, sputter, polymerization, etc.).; A tool has been developed which provides all of these features through the coupling of heterogeneous code modules (hybrid plasma, Particle In Cell (PIC) plasma and solid surface chemistry) and through time-sampling techniques. The hybrid code (particle ions, fluid electrons) provides the basis for modeling the large-scale plasma reactor using a finite-element mesh to represent complex reactor geometries. The PIC code is used in the dynamic sheath boundary region to account for electron movement. The solid surface chemistry code is specially developed to model complex interactions between surface mechanisms, such as the formation of polymer and its possible removal by high-energy particles. The solid surface module uses a finite element scheme with adaptive mesh refinement to follow the complex surface evolution. These code modules exchange information on a sub-RF-period timescale, allowing for direct solid/plasma interactions. The long process times (minutes) are simulated by result-sampling and using the slow evolution of the plasma/solid system. The code also performs surface charge migration and local gas heating to more completely represent the physical processes occurring in a plasma processing operation.; The modeling of plasma processing must also account for the multi-layer films and many species of particles and material types. The incorporation of this information in the simulations has demonstrated mask erosion. The simulations performed using this code have also shown good correlation to experimental results for steady state etch rates, etch rates as a function of via size, sidewall polymer evolution, and the production of "sputter wind" and surface charging. In deposition mode, the simulations demonstrate the experimentally observed polymer and deposited film topology. |
