Boron cathodic arc as an ion source for shallow junction ion implantation of boron

For the last ten years, one of the most important topics in the literature for ion implantation of semiconductors has concerned delivery of boron ions at low energies for the 65, 45, and 32 nm technologies and beyond. The vacuum arc ion source produces a very strong (2 A), fully space-charge compensated plasma of 100% ionized boron single atoms with no gas atoms and few foreign atoms in the plasma. These qualities potentially make delivery of boron for ion implantation rather simple in comparison with competing techniques. Key issues pertaining to possible use of the source in a simple delivery scheme are dealt with experimentally. These issues are macroparticle filtering, impurity content, doubly charged ion content, and implantation results at low energy. Quantitative results for the first two are presented. These results include design strategies and performance of a novel macroparticle filter. Satisfactory performance, as far as multiple charging is concerned, is inferred from the implantation results. That conclusion follows from the fact that secondary-ion-mass spectroscopy profiles in silicon reflect range containment of the B that is as good, or better, than for other techniques. It is further concluded that there are no fundamental obstacles to further advancement of the technology in the doping application. A simple compact prototype front end concept is proposed.