Shape, stress, and electrical leakage in advanced isolation structures

Process simulation reduces the cost of new technology development by replacing experiments with computer simulations. A computer tool that uses physical models is more broadly useful than an empirically based tool. In silicon technology simulation, the models are physical based equations that are solved for dopant diffusion, oxide growth, deposition, and etching steps needed to fabricate VLSI circuits. The increasingly high costs and the complexity of VLSI technology have made the application of semiconductor process simulators very important. If the models can accurately predict experimental results, or obtain target parameters, the use of simulators can reduce the traditional wafer split-runs and minimize the costly empirical approach. However, because of the complexity of the IC fabrication process, many sequential operations are needed to simulate one process flow, and a small error introduced in the approximation of a process step can be exacerbated in the final result. Thus, a combination of measurements, experiments, and simulations is still required to develop new process flows. This research study has been an attempt to achieve both fundamental scientific understanding of isolation process physics and improvement of computer simulation tools. LOCOS-type isolations and shallow trench isolations have been studied with simulation and with experiments.