TABLE OF CONTENTS In general, physical vapor deposition (PVD) from the gas phase is subdivided into four groups, namely (i) evaporation, (ii) sputtering, (iii) ion plating, and (iv) laser ablation. The first three methods occur at low pressures. A rough overview is seen in Fig. 4.1.
Evaporation. This procedure is carried out in a bell jar as depicted in Fig. 4.2. A crucible is heated up by a resistance or an electron gun until a sufficient vapor pressure develops. As a result, material is deposited on the substrate. Technically, the resistance is wrapped around the crucible, or a metal wire is heated up by a current and vaporized. The electron gun (e-gun) produces an electron beam of, e.g., 10 keV. This beam is directed at the material intended for the deposition on the substrate. The gun's advantage is its unlimited supply of evaporating material and applicability of non-conductive or high-melting materials. Its shortcomings lie in the production of radiation defects, for instance in the underlying oxide coating. Both procedures are more precisely depicted in Fig. 4.3.
Figure 4.2: Vacuum system for the vaporization from resistance-heated sources. When replacing the transformer and heater with an electron gun, vaporization by means of an electron beam occurs [54].
Figure 4.3: Evaporation by means of resistance-heating with a tungsten boat and winding (a) and electron gun (b) [55]
Sputtering.
