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Laser-assisted atom probe tomography of Ti/TiN films deposited on Si

Published

Author(s)

Norman A. Sanford, Paul T. Blanchard, Ryan M. White, Michael R. Vissers, Albert Davydov, D R. Diercks, David P. Pappas

Abstract

Laser-assisted atom probe tomography (L-APT) was used to examine superconducting TiN/Ti/TiN trilayer films with nominal respective thicknesses of 5/5/5 (nm). The trilayers were deposited on Si substrates by reactive sputtering. Electron energy loss microscopy performed in a scanning transmission electron microscope (STEM/EELS) was used to corroborate the L-APT results and establish the overall thicknesses of the trilayers. Three separate batches were studied where the first (bottom) TiN layer was deposited at 500 ⁰C (for all batches) and the subsequent TiN/Ti bilayer was deposited at ambient temperature, 250 ⁰C, and 500 ⁰C, respectively. L-APT rendered an approximately planar TiN/Si interface by making use of plausible mass-spectral assignments to N31+, SiN1+, and SiO1+. This was necessary since ambiguities associated with the likely simultaneous occurrence of Si1+ and N21+ prevented their use in rendering the TiN/Si interface. The non-superconducting Ti2N phase was revealed by L-APT and was most prominent near the bottom Ti/TiN interface. Neither L-APT nor STEM/EELS rendered sharp Ti/TiN interfaces and the contrast between these layers diminished with increased film deposition temperature. L-APT also revealed that hydrogen was present in varying degrees in all samples including control samples that were composed of single layers of Ti or TiN.
Citation
Micron

Keywords

atom probe, laser assisted atom probe tomography, electron energy loss spectroscopy, TiN, superconducting thin films
Created December 21, 2016, Updated February 26, 2018