SYNCHROTRON RADIATION PHOTOIONIZATION OF SPUTTERED NEUTRALS

A photoionization effect of sputtered neutrals by synchrotron radiation (SR) is observed for the first time. Synchrotron radiation from a bending magnet is irradiated 5 mm “above” the Ar ion sputtered area of the sample surfaces, and photoionized ions and secondary ions are detected with a quadrupole mass spectrometer with and without this SR irradiation. A large ratio of photoionized ions to secondary ions is obtained when Au and Pb are sputtered with a low primary Ar ion energy. On the contrary, no detectable photoionization effect is observed from Al, Si, or GaAs. These results are explained qualitatively by the photoionization process where the number of generated ions can be calculated based on the photon flux density, photoionization cross sections, and duration in which sputtered neutrals pass through the SR beam. © 1990, American Vacuum Society. All rights reserved.