title: Direct chemical in-depth profile analysis and thickness quantification of nanometer multilayers using pulsed-rf-GD-TOFMS.
abstract: Nanometer depth resolution is investigated using an innovative pulsed-radiofrequency glow discharge time-of-flight mass spectrometer (pulsed-rf-GD-TOFMS). A series of ultra-thin (in nanometers approximately) Al/Nb bilayers, deposited on Si wafers by dc-magnetron sputtering, is analyzed. An Al layer is first deposited on the Si substrate with controlled and different values of the layer thickness, t(Al). Samples with t(Al) = 50, 20, 5, 2, and 1 nm have been prepared. Then, a Nb layer is deposited on top of the Al one, with a thickness t(Nb) = 50 nm that is kept constant along the whole series. Qualitative depth profiles of those layered sandwich-type samples are determined using our pulsed-rf-GD-TOFMS set-up, which demonstrated to be able to detect and measure ultra-thin layers (even of 1 nm). Moreover, Gaussian fitting of the internal Al layer depth profile is used here to obtain a calibration curve, allowing thickness estimation of such nanometer layers. In addition, the useful yield (estimation of the number of detected ions per sputtered atom) of the employed pulsed-rf-GD-TOFMS system is evaluated for Al at the selected operating conditions, which are optimized for the in-depth profile analysis with high depth resolution.
authors.affiliation: Department of Physics, University of Oviedo, Campus de Mieres, c/ Gonzalo Gutierrez Quiros, 33600 Mieres, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Valledor
authors.forename: J
authors.initials: J
authors.lastname: Pisonero
authors.forename: N
authors.initials: N
authors.lastname: Bordel
authors.forename: J I
authors.initials: JI
authors.lastname: Martín
authors.forename: C
authors.initials: C
authors.lastname: Quirós
authors.forename: A
authors.initials: A
authors.lastname: Tempez
authors.forename: A
authors.initials: A
authors.lastname: Sanz-Medel