Characteristics of a large diameter reactive ion beam generated by an electron cyclotron resonance microwave plasma source

A new ion source with a large beam diameter generated by an electron cyclot ron resonance microwave plasma source is presented. Ion beams with a beam d iameter of >160 mm and a maximum argon-ion current density of 2.1 mA/cm(2) are obtained. For this large two-electrode silicon-ion extraction optics ar e mounted into an electron cyclotron resonance microwave plasma source. Wit h ion extraction optics installed an electron temperature up to three times higher than without optics was observed. Due to this high electron tempera ture (up to 12 eV) the O+ concentration is enhanced in an oxygen plasma. Th erefore, a concentration as compared to the O-2(+) an ion current density o f 1.1 mA/cm(2) can be generated. Ion energies of 1 keV corresponding to the screen grid voltage are obtained with a small energy spread of 10 eV full width at half maximum or less. The low working pressure (about 10(-4) mbar) is well suited for low-pressure ion-beam processes. (C) 2001 American Vacu um Society.