Evaporators with Induction Heating and Their Applications

Induction heating is widely used in different fields due to high process productivity and universality, cleanness and possibility of full automation. This process is friendly for environment. Since the induction allows reaching temperatures of 2000 °C and more, this method is very suitable for evaporation. This process is known to be a process of emitting atoms or molecules by hot matter surface. The atoms or molecules form “the vapor”. Since vapor pressure depends on temperature, the latter is conditionally accepted as “the evaporation temperature” when pressure of saturated vapor reaches 1 Pa. Data on evaporation temperatures are collected in numerous handbooks, e.g. (Banshah, 1994). The evaporation is a very important process for industrial production and scientific researches. Its main application is deposition of thin film layers and coatings on semiconductors, glass and polymers in electronics and optics as well as on other industrial products including food packaging films, metal strips, etc. The evaporation is mostly related with technology of Physical Vapor Deposition (shortly, PVD) that means matter deposition from vapor or atomic/molecular medium. In PVD, the vapor medium, as a source of depositing matter, is generated physically (not chemically!) due to thermal evaporation of some primary source materials; deposition, in turn, must happen as atom-by-atom process, at least as multi-atom cluster process but without any drops or even smallest droplets. There are various evaporation methods for PVD except induction: evaporation from boats and crucibles with resistive (Joule) or radiation heating, evaporation with electron and laser beam heating, cathode arc evaporation, etc. The induction technology competes with the mentioned methods and occupies own niche in industrial technology and for preparation of scientific objects. The evaporation also is a very useful process for refining materials to obtain high purity, for producing microand nanoparticles and, thus, it is a base of so-called evaporation metallurgy. The main features and fundamental possibilities of the evaporating induction technology are the followings: electromagnetic induction may provide not only heating evaporated materials but also vapor ionization and high density vapor plasma generation for Ion-Plasma Enhanced (Activated, Assisted) PVD processes, often called as the Ion Plating, accompanied by self-ion bombardment for obtaining high quality coatings;