Secondary ion emission from metal targets under carbon trifluoride ion (CF3+) and oxygen ion (O2+) bombardment

Abstract

CF/sub 3//sup +/ has been extracted from a cold cathode ion gun supplied with a CF/sub 4//N/sub 2/ gas mixture. A CF/sub 3//sup +/ beam current of about 200 nA is obtained, which is about a factor of 5 smaller than the approx.1 ..mu..A O/sub 2//sup +/ beam currents obtainable from conventional oxygen ion sources. This decrease is partially offset by the higher sputter yields obtained with CF/sub 3//sup +/. Ionization probabilities are higher or equal to those found for O/sub 2//sup +/ bombardment. Composition and chemical state analyses were performed after saturation bombardment. Generally metal carbides are found to have formed with a fluorine uptake of about 10-20 atom %. The fluorine is bonded to the metal. Matrix effects are smaller under O/sub 2//sup +/ bombardment due to the low fluorine concentration.