THEORY OF OPERATION of Thermal

Evaporation is a powerful technique for thick metal or organic coatings. It is a vapor phase deposition technique and requires good vacuum. High temperatures must be reached to vaporize the material under vacuum to coat the substrate. Typically any material where evaporation temperature is less than 2000 0C can be evaporated at about 10-5 Torr for coating. However, appropriate crucibles (Alumina, Quartz, Boron Nitride etc) with proper baskets or boats must be chosen. Organic materials require lower temperatures (about 6000C) but better controlled.
Some materials have low sticking coefficient making it difficult to build a film or require substrate heating (optional) to control stoichiometry. These problems can be overcome by pressure and heating control. Having a computer-controlled system we can assure low background pressure is reached before evaporation can start. Especially at the beginning, impurities that outgas can be pumped down by heating the empty crucible or the boat.