Plasma activated high-rate deposition with axial electron beam guns

Electron Beam High-rate Deposition with axial guns (EBHD) offers the highest coating rates of PVD technologies and shows growing industrial application. The route to ever higher coating speeds is complicated in that layers coated at high rates have a marked columnar structure. This makes them unsuitable for many applications. The effect is caused by the low energy of the vapor particles with EBHD. Plasma activation during deposition increases effectively the vapor particle energy and therewith changes drastically the properties of the deposited layers. In the SAD process (Spotless arc Activated Deposition) the EBHD is combined with a special vacuum arc discharge. The hottest point of the material being evaporated is the cathode foot point of the discharge. For selected metals, especially those with high melting points, the cathode foot point is diffuse at evaporation temperatures rather than being limited to less than 1 mm² as for known arc discharges. This ""diffuse foot point"" occupies an area of many cm² and does not emit any droplets. The combination of EBHD with a hollow cathode arc discharge forms the basis of the HAD process (Hollow cathode arc Activated Deposition). For large area deposition some hollow cathodes are installed side by side and their discharges penetrate the vapor cloud. This process is particularly suitable for reactive deposition with insulating compounds such as silicon and aluminum oxides.