Compositions in layers modified by ion beam dynamic mixing to improve the adhesion of cBN films and in situ ion measurement

Abstract

The depth profiles of elements in layers modified by ion beam dynamic mixing (IBDM) on substrates which unproved the adhesion of cubic boron nitride (cBN) films were studied by Auger electron spectroscopy (AES). The measurements of mass spectra and energy distribution of ions during IBDM were also undertaken in order to monitor the surface composition of the modified layer. The IBDM was performed on WC-Co coated with TiN by irradiation of ions of nitrogen mixed with argon with an energy of 7 keV and simultaneous evaporation of boron. Only a mixed layer, composed of a gradient mixture of boron, nitrogen and the elements of the substrate, was formed on the substrate under a suitable boron/ion arrival ratio. However, the mixed layer was covered by a boron-rich layer whose B/N atomic ratio was in excess of the stoichiometric value of unity with increases in the boron/ion arrival ratio. In situ measurement of boron and titanium secondary ions from the surface of the modified layer, and boron vapor and atmosphere gases ionized by the ion beam, were possible during IBDM. The changes of the intensity ratio with operating time of secondary ions of titanium to those of boron, correlated well with the depth profiles of the titanium composition by AES.