title: Laser-assisted atom probe tomography of Ti/TiN films deposited on Si.
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). Such materials are of interest for applications that require large arrays of microwave kinetic inductance detectors. 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°C (for all batches) and the subsequent TiN/Ti bilayer was deposited at ambient temperature, 250°C, and 500°C, 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 upon reconstruction. The non-superconducting Ti2N phase was also revealed by L-APT. 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.
authors.affiliation: National Institute of Standards and Technology, Physical Measurement Laboratory, Division 686, 325 Broadway, Boulder, CO 80305, United States. Electronic address: sanford@boulder.nist.gov.
authors.forename: N A
authors.initials: NA
authors.lastname: Sanford
authors.affiliation: National Institute of Standards and Technology, Physical Measurement Laboratory, Division 686, 325 Broadway, Boulder, CO 80305, United States.
authors.forename: P T
authors.initials: PT
authors.lastname: Blanchard
authors.affiliation: National Institute of Standards and Technology, Material Measurement Laboratory, Division 647, 325 Broadway, Boulder, CO 80305, United States.
authors.forename: R
authors.initials: R
authors.lastname: White
authors.affiliation: National Institute of Standards and Technology, Physical Measurement Laboratory, Division 687, 325 Broadway, Boulder, CO 80305, United States.
authors.forename: M R
authors.initials: MR
authors.lastname: Vissers
authors.affiliation: Colorado School of Mines, Department of Metallurgical and Materials Engineering, Golden, CO, 80401, United States.
authors.forename: D R
authors.initials: DR
authors.lastname: Diercks
authors.affiliation: National Institute of Standards and Technology, Material Measurement Laboratory, Division 642, 100 Bureau Drive, Gaithersburg, MD 20899, United States.
authors.forename: A V
authors.initials: AV
authors.lastname: Davydov
authors.affiliation: National Institute of Standards and Technology, Physical Measurement Laboratory, Division 687, 325 Broadway, Boulder, CO 80305, United States.
authors.forename: D P
authors.initials: DP
authors.lastname: Pappas