DEVELOPMENT OF AN ION-SOURCE FOR THE LOW-ENERGY ION-IMPLANTATION

A mass-selected ion source has been developed for low energy ion impla ntation. The use of high current and low energy ion beam causes the ta rget charge-up and space charge problem in the beam transport line. We have used the large area ion source without mass separation. The ioni zation energy of hydrogen is higher than that of diborane. If we can c ontrol the energy of electrons in the plasma, we can design a hydrogen -free ion source. In order to make clear the relationships between the energy of electrons and r.f. discharge parameters, we measured the r. f. discharge parameters with a Langmuir probe while changing the radio frequency, r.f. power and so on. The proportion of the hydrogen ions to total ions generated in the plasma could then be less than 1%. (C) 1998 Elsevier Science S.A. All rights reserved.