Electron Collision Data for Plasma-Processing Gases
Loucas G. Christophorou, James K. Olthoff
Low-temperature plasma applications require detailed understanding of the physical and chemical processes occurring in the plasmas themselves. For instance, as the push for smaller feature sizes and higher quality devices in the semiconductor industry has increased, so has the need for sophisticated models with predictive capabilities that can guide the technology, and the need for advanced diagnostics to probe the details of the plasmas used to etch features, deposit materials, or clean reactor chambers. In addition, environmental concerns have fostered the demand for the more efficient use of global warming gases used in plasma processes. Advancement in each of these areas inherently requires detailed understanding of the physics and chemistry occurring within the discharge, which itself requires knowledge of the basic collision processes taking place between the species existing in the plasma. The most fundamental of the discharge processes are collisions between electrons and atoms, radicals, or molecules. These collisions are the precursors of the ions and the radicals that drive the etching, cleaning, or deposition processes. Hence, a quantitative understanding of the fundamental electron collision processes in terms of cross sections and rate coefficients is of the utmost importance. This chapter deals with fundamental data necessary for targets of importance in the plasma etching of silicon. It draws heavily from the work we have conducted at the National Institute of Standards and Technology (NIST) over the last four years under a project aimed at building a database for electronic processes in plasma processing gases, including cross sections, and electron transport and rate coefficients.
Advances in Atomic, Molecular, and Optical Physics