AN ECR MICROWAVE PLASMA CATHODE FOR ION SOURCES WITH ELECTROSTATIC REFLEX CONTAINMENT

Ion sources for industrial reactors are used in a lot of applications such as ion beam sputtering or etching, ion assisted thin-film deposition, and surface treatment. They must satisfy several conditions; three of them are most important for reactive, especially oxygen, ion beams: (1) a lifetime longer than 100 h, (2) no deposition of an insulating film on the electrodes, (3) the electron energy must be chosen in a given range in order to control the fragmentation of the injected neutrals. The aim of this work was to compare the behavior of two ion sources having the same microwave plasma cathode, where the plasma is created by a microwave field (2.45 GHz) under an ECR condition: an electrostatic reflex ion source (ERIS) and a multipolar electrostatic reflex ion source (MERIS). Typically, we have produced an oxygen beam current of 83 mA with the ERIS structure and 118 mA with the MERIS structure, in 84 mm diameter for an extracted energy of 1200 eV. We have obtained broad uniform oxygen beams during about 100 h with both sources. A comparison between figures of the two structures is given, concerning the discharge characteristics, the extracted current, the yield, and finally, the extracted beam profile.