No abstract

An unexpected substrate etching phenomenon during the sputtering of certain intermetallic compounds has been found to be caused by a large flux of negative metal ions from the sputtering target. The substrates directly under the target in a diode geometry are etched (eroded) rather than coated with a film. The occurrence of this substrate etching has been correlated with negative ion yields measured by secondary ion mass spectroscopy (SIMS). We find a high yield of negative metal ions from several intermetallic compounds in addition to the highly ionic compounds previously reported. A model based on electron charge transfer is presented which predicts when negative ion formation will be important, and the dependence of etch rate on target voltage is also treated. We predict that negative ion effects will be found in the sputtering of a wide range of compounds.

No abstract

A modified equation is proposed for the X-ray production range of 2-15 keV electrons in solids. The modification is obtained by an experimental procedure which compares the difference in X-ray intensities between pure element thin films and 'bulk' standards. The elements evaluated were Al, Ti, Ni, Zr, Nb, Mo, Pd, Ta and Pt. Monte Carlo simulations were made for several of the elements and agree with experimental results to within 5%. There was one exception, in the case of a high-atomic-number film (Pt on Si) at low keVs. Here the deviation increases to 10-20%. The modified equation is also compared to other range equations in the literature.