Alumina Coated Sources

The aluminum oxide (AO) coated evaporation sources was developed to replace alumina crucible boats in thermal evaporation. Semiconductor-grade aluminum oxide is applied to the boat/basket by plasma spray technique.

Properties of Alumina Coatings

Alumina displays inertness with most molten metals. AO coated sources will require 30-50% more power to affect evaporation due to differences in thermal conduction. When evaporation is affected, power should be slightly reduced to avoid overheating.

• Relatively efficient heat transfer in conditions up to 1850°C
• Longer source lifetime for difficult materials (e.g. nickel)
• AO coating layer prevents change in boat resistance caused by molten metal contact
• Non-wetting with evaporant forms a sphere when melted, acting as a point source

Tungsten & Molybdenum Boats with Alumina Barriers

Alumina coatings done in a barrier-style exposes a metal area at the bottom of a boat while maintaining a perimeter of alumina. This allows evaporant to have direct thermal contact with the boat, while also inhibiting material creeping or wetting toward the boat or heat sink.