Oxygen implants using water vapor as source feed gas in high and medium current implanters

Refractory metals used in ion sources (such as tungsten) will oxidize using ordinary oxygen bearing gases for oxygen implantation. By comparing the free energy of formation of different feed gases with tungsten oxide it was found that for temperatures between 960°C and 3300°C tungsten will preferably not oxidize in a water vapor environment. For high current implanters the tungsten arc chamber walls and filaments operate in this temperature range, making water a viable feed gas for O⁺ implants. Stable beam currents of up to 7.5 mA have been achieved.