A comprehensive study of molybdenum boats behavior during service life for continuous thermal evaporation technique, used in thin film technology

The aim of this study is to calculate the optimum lifetime of Molybdenum (Mo) thermal evaporation boats for Copper (Cu) filling in thin film technologies. Three types of Mo boats with thicknesses of 0.2, 0.3 and 0.5 mm were used during the experiments under the high vacuum condition about 6.0 × 10−6 Torr. The behavior of each boat was investigated by focusing on the total amount of evaporation material, operational time and applied power. Prior to the deposition process, material was loaded on the evaporation boat by two methods. In the first method, Cu wire was cut into 1 cm long, then every boat was filled with this amount of Cu material. The second alternative feeding method is to use a wire-feeder step motor, which refills boat with Cu wire during evaporation process. The latter one is very useful for continuous deposition process since there is no need to break the vacuum state. In both methods, however, the number of failures during operations increases after a series of experiments have been taken place because of boat aging. The results of failures have been analyzed by various methods, and it has been observed that thinner boats showed better stability for long time operation by continuous feeding technique. •The performance of molybdenum boats depends on their thicknesses in continuous deposition.•A series of operational failures are getting increased as a result of boat aging.•Operational power ratio increases with respect to boat aging during process.•It could be possible to obtain a relation between lifetime and maximum material mass.•When the boat is thinner, the performance and stability are much better.