SURFACE PROCESSES IN LOW-PRESSURE PLASMAS

In many high technology industries low pressure plasmas have become in dispensable for advanced materials processing: the microelectronics in dustry employs plasma-based etching to produce sub-micron device featu res in thin films with precisely controlled dimensions and uses plasma -enhanced chemical vapor deposition methods to synthesize insulators, conductors, diamond thin films and high-temperature superconductors. P lasmas are also used to harden the surfaces of cutting tools and modif y the surfaces of polymers and other materials. Even the simplest plas ma processing reactor is scientifically extremely complex, and the cha racterization and understanding of plasma-surface interactions is one of the least understood parts of the overall problem, We review scient ific issues, the experimental tools to study these, and survey results of surface process characterization of plasma etching processes of mi croelectronic materials. We will show that the process etch quality in a low pressure plasma is often directly related to the thickness and composition of the reaction layers that form on the various surface th at are exposed to the plasma. The characteristics of the surface react ion layers are controlled by the chemical composition of the discharge , the ion bombardment energy and ion fluxes at the substrate. (C) 1997 Elsevier Science B.V.