スパッタ成膜中のイオン衝撃が Ni 薄膜の内部応力に及ぼす影響

Abstract

In this study, the effects of an ion bombardment parameter Pi of argon (Ar) ,k rypton(Kr) and xenon (Xe) on the internal stress and crystal structure of a nickel (Ni) thin film were discussed. Ni thin films were prepared by a DC magnetron sputtering process. Ar, Kr and Xe were used as sputtering gases. As a means of expressing the effect of ion bombardment, the ion bombardment parameter Pi based on the magnitude of ion momentum PG＋ ( G: Ar, Kr or Xe) and an impingement ratio of sputtering gas ions iG＋ to that for Ni particles aNi was proposed. Plasma diagnostics were carried out with a single Langmuir probe during the sputter deposition. The magnitude of the ion momentum estimated from the plasma potential was independent of the cathode discharge power. With an increase in cathode discharge power, the increase in aNi onto the substrate was greater than the increase in iG＋. It has become evident that the ratio of impingement iG＋ to aNi onto the substrate mainly affects the variation in Pi in relation to the cathode discharge power. The FWHM (full width at half maximum) of Xray diffraction peaks and the internal stress of the films varied linearly with the ion bombardment parameter Pi regardless of the sputtering gas species. The internal stress of Ni thin films could be controlled by adjusting the ion bombardment parameter Pi. [doi:10.2320/jinstmet.JBW201302]