Microwave ion source for ultra clean ion implanters

An advanced microwave ion source has been developed in order to achieved high purity ion beams and long source life. The source generates no metallic contamination as the plasma chamber is made of a chemically stable sure ceramic. The source life is also extended be on order of magnitude as the source materials fed into the chamber are directly ionized without using cathodes. The ion source has a unique feature of controlling the magnetic field profile across the plasma chamber by the use of a closed magnetic circuit and the shaped magnet poles. This feature, combined with the low ripple microwave generator, made it possible to achieve a wide dynamic range of plasma density (1*10 ¹⁵-1*10¹⁹ ion/cm³). The source can be operated in either ECR or Off ECR mode in order to adjust the level of ionization, which is extremely useful when extracting ions form molecular source materials. This paper discusses the structure and the characteristics of the microwave ion source in terms of magnetic field profile, microwave propagation, plasma density, level of ionization and the dynamic range of beam current. The ion source was operated on an Applied Materials xR80 Ion Implanter