A first approach to counteract the challenges of vapor deposition is to increase the impact energy on the substrate. This allows denser layers with better adhesion to be produced. To achieve this, a jet of vapor must be generated instead of a cloud of vapor.
The vapor pressure above the source must be significantly increased compared to the pressure in the vacuum chamber. This is achieved by enclosing the vaporization source with an outlet nozzle.
Due to the small outlet cross-section, the steam accumulates in front of the nozzle and exits at high speed. The result is a directed jet of steam that hits the substrate at high speed and condenses. Due to the high impact speed, the coating can be compacted and the adhesive strength increased.
The vapor pressure generated during the evaporation of zinc can be up to 1.5 bar above the evaporation crucible, depending on the temperature. The nozzles of such an evaporator are usually designed as Laval nozzles. The vapor is therefore emitted at the speed of sound or even ultrasound due to the high pressure difference to the vacuum chamber.
NEOVAC's cutting-edge Plasma Enhanced Evaporation technology is a further development of the convectional Vapor Jet process