Abstract
Supersaturated Ti(N) thin films have been prepared by the combination of low temperature nonequilibrium processes of ion beam sputtering (IBS) and ion implantation method. Ti thin films of 150 nm in thickness have been deposited on (001) Si substrate by IBS. N + ions have been penetrated into the films with the dose of 1×10 17∼2×10 18 ion/cm 2. The structural changes due to the N-implantation and successive heat treatments have been evaluated by X-ray photoelectron spectroscopy (XPS) chemical analysis and cross-sectional transmission electron microscopy (TEM) observation. The distribution of N atoms in N-implanted Ti films has been measured by XPS. The maximum concentration of N was achieved at the Ti/Si interface with beam energy of 100 keV. The linear increase of the binding energy shift in proportion to the N concentration suggests that N-implanted Ti films consist of Ti(N) supersaturated solid solution. From TEM observation, as-deposited Ti films show the conventional hcp structure with columnar grains 10 nm in diameter. These grains with growth direction of [0001] α develop perpendicular to the (001) Si substrate. N-implantation results in the film having the complex structure of α-Ti(N) solid solution with small amounts of ɛ-Ti 2N and δ-TiN. Formation of the ɛ-Ti 2N is recognized from electron diffraction for the N-implanted specimen with 1×10 17 ion/cm 2 and the δ-TiN phase for the specimen with 5×10 17 ion/cm 2. The lattice constant has been measured from electron diffraction and the c/ a ratio of hcp-Ti(N) increases in proportion to the N concentration toward the theoretical value for cubic structure. The XPS compositional measurement suggests that N-implantation induces the anomaly saturated N in hcp-Ti(N) lattice. The lattice constant of hcp-Ti(N) decreases by postannealing treatment at 773 K. Postannealing promotes the phase decomposition of supersaturated solid solution of hcp-Ti(N) into meta-stable nitrides.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
