Synthesis of co-sputter deposited Ni-Ti thin alloy films and their compositional characterization using depth sensitive techniques

摘要

Ni-Ti (Nickel-Titanium) thin alloy films of different concentration and thickness were synthesized using magnetron co-sputtering process utilizing separate Ni and Ti targets. Concentrations of Ni and Ti in the deposited films were optimized by controlling the power ratio of individual Ni and Ti targets. Thickness and density of the layered structures present in the films were evaluated by X-ray Reflectivity (XRR). Atomic concentrations of Ni and Ti were determined by Energy Dispersive X-ray Spectroscopy and matched with the concentrations obtained through XRR measurements. Secondary Ion Mass Spectrometry and Rutherford Backscattering Spectrometry were utilized to investigate the elemental depth distributions of Ni, Ti and 0 content in the films. Depth distribution studies confirmed that oxygen as a surface contaminant was present in all the deposited films, although films having thickness in the range of 21.5 nm -22.7 nm, were found to contain oxygen within the films too. Thicker Ni-Ti alloy films, in the range of 51.3 nm -52.3 nm, did not reveal any oxygen contamination in the bulk of the films. X-ray Photoelectron Spectroscopy (XPS) was used to determine elemental and molecular content of the deposited films. XPS analysis confirmed the presence of NiO at the surface and intermetallic Ni-Ti within the deposited films.