Chapter 2 - Plasmas in Deposition Processes

Abstract

This chapter surveys fundamental aspects of plasmas as they relate to materials processing, particularly deposition and surface modification. This includes the basics of gas-phase interactions, discharge physics, and plasma–surface interactions. Plasmas are partially ionized gases that contain approximately equal numbers of positively and negatively charged species. Their unique properties, however, make them a powerful tool used in the modification of materials, ranging from material removal (etching) to the deposition of thin films and coatings. Plasmas are significantly different from nonionized gases; a consequence of the mass difference between the positively charged ions and negatively charged electrons as well as the energy of these species. Although a number of plasmas have been used in materials processing including arcs, flames, and electron beam-generated plasmas, the most common types are discharge plasmas, generated by applying an electric field to a volume of gas. Processing application areas that utilize plasmas include: sputter deposition, reactive sputter deposition, activated reactive evaporation, ion plating, plasma-assisted chemical vapor deposition (PACVD), plasma-assisted physical vapor deposition (PAPVD), plasma-assisted etching, and plasma polymerization. The production of plasma and plasma-based systems for materials processing is flexible. There are many approaches to plasma production and each method has its advantages in terms of plasma and system characteristics. Plasma-based systems are common to a wide range of applications. The development of new plasma-based processing systems has driven the evolution of materials and vice versa.