Ion sources for the varying needs of ion implantation

Abstract

A joint research and development effort whose ultimate goal is to develop steady-state intense ion sources to meet the needs of the two energy extremes of ion implanters (mega-electron-volt and of hundreds of electron-volt) has been in progress for the past two years. Present day high-energy ion implanters utilize low charge state (usually single charge) ion sources in combination with rf accelerators. Usually, a MeV linear accelerator is used for acceleration of a few milliamperes. It is desirable to have instead an intense, high charge state ion source on a relatively low-energy platform (dc acceleration) to generate high-energy ion beams for implantation. This endeavor has already resulted in very high steady-state output currents of higher charge states antimony and phosphorous ions. Low-energy ion implantation is performed presently by decelerating high-energy extracted ions. Consequently, output currents are low due to space charge problems. Contamination is also a problem due to gases and plasmas employed to mitigate the space charge issues. Our efforts involve molecular ions and a plasmaless/gasless deceleration method. A program overview is presented in this article. Although source specifics are described in accompanying papers, only this article contains our most recent results.