Post-vaporization ionization

The anodic or distributed arc sources are basically evaporation sources heated by low voltage, high current unfocused e-beams (Sec. 6.3.1). The e-beam can be bent by a magnetic field so that the emission source is out of hne of sight of the evaporation source, as shown in Figure 8.1 (c), or it can he in the hne of sight. The electrons can be made to spiral in a magnetic field so as to increase the post-vaporization ionization probabflity of the evaporated material. 

Ion plating, using film ions , is used to fill vias and trenches on semiconductor surfaces by sputter deposition. By post-vaporization ionization of the film atoms and accelerating the ions to the surface, they arrive with a nearer to normal angle-of-incidence (collumination) than if they were sputter deposited without ionization and acceleration. 

Significant fluxes of film ions are obtained during arc vaporization, HIPIMS, laser vaporization, and by post-vaporization ionization in sputtering and thermal evaporation. Often film ions are mixed with neutral film species and the composition of the flux is not known. In some cases, the film ions are deflected so that a pure film ion beam is deposited, such as in the use of a plasma duct to eliminate globules from an arc source. 

Post-vaporization ionization (PVD technology) The ionization of the vaporized (sputtered or evaporated) film atoms to form film ions that can be accelerated in an electric field. See also Film ions. 

The use of accelerated ions of the film material ( film ions ) allows the formation of a pseudodiffusion-type interface. Film ions can be formed by the ionization of vaporized material. This occurs naturally in arc vaporization, which uses a high current of low voltage electrons, to vaporize material from a cathode or anode (Ch. 8), and HIPIMS (Ch. 7). Alternatively, ions can be formed by post-vaporization of sputtered atoms or evaporated atoms. 

In this chapter we concern oiuselves with the laser-induced vaporization of neat polymers, hi this case, without ionic dopants or ions created by laser-induced breakdown, there is no chemical ionization and the gas phase polymer molecules are neutral. Post-ionization is thus necessary to convert them into ions. Since this is usually done by a second pulsed laser the procedure has also been called two-step laser mass spectrometry. ... 

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