Modeling and profile simulation of silicon and metal etching in integrated circuit manufacturing

Plasma etching is one of the semiconductor processing technologies, which has advanced tremendously over the last decade in order to meet the demands of ever increasing density of devices manufacturable in integrated circuits. A plasma etch process is usually based on a combination of chemical and physical mechanisms and has to be developed case by case in order to meet the specific demands of a process flow. Most of these processes have been accomplished by using low pressure discharge plasma systems. However, because of the complexities of such systems and our limited understanding of the many types of discharge plasmas and plasma surface interactions, a good amount of the process development work has been done on an empirical basis.;This thesis is built upon the development and applications of SPEEDIE, the Stanford etching and deposition profile simulator, which is aimed at helping process engineers to develop and understand plasma etch processes. It starts with an introduction to semiconductor processing, which focuses on etching and discusses about the many requirements a good etching process has to meet. A detailed description of etching plasmas and the etching plasma systems follows after this introduction. We then give an overview of the SPEEDIE program, which covers the flow structure, the physics and the mathematics behind the basic part of the codes and the surface movement algorithm. The rest of the thesis is a demonstration of how SPEEDIE can be applied to various cases such as silicon and metal etching. These applications have lead to the discovery of the effect of the pre-sheath of a discharge plasma on the ion angular and energy distributions at the wafer surface. We have also clarified a few concepts associated with energetic ion assisted surface reactions. We have found that the surface catalyzed reactive species recombination is crucial to explain the strong aspect ratio dependency during metal etching. SPEEDIE is shown here to produce many important results, which have lead us to a deeper understanding of the etching plasmas and of the plasma-surface interactions.