Mechanism of formation and some surface characteristics of thin polymer films formed on metal surfaces by electron bombardment

The formation of thin films by electron bombardment has been studied and some of the important factors controlling the nature and surface characteristics of the films have been identified. A number of experimental techniques have been developed in order to obtain information on both the species likely to be involved in film growth and also the nature of the film surfaces. The surface characteristics have been monitored by contact angle studies. The possible importance of negative ions in film formation is illustrated with Si(CH₃)₄, where over 20 different negative ions were detected, the major ones being H^-, C₂H- and SiC₂^-. Such results also have an important bearing on electron affinity data obtained by the magnetron method. Thin films formed from perfluorobut-2-ene have surface characteristics which vary with the monomer pressure, the substrate temperature, and electron and ion energies. Information on the relative importance of the role of negative ions compared with electron and adsorbed monomer reaction is obtained. Some suggestions are discussed regarding possible surface structures inferred from wetting characteristics.