Dresden 2006 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 24: Poster presentation

DS 24.46: Poster

Dienstag, 28. März 2006, 15:00–17:30, P2

Femtosecond Laser Ionization Mass Spectrometry for Analysis of Multi-layered Structures — •Lei Zhu^1,2, Florenta Costache^1,2, Markus Ratzke^1,2, and Jürgen Reif^1,2 — ¹LS Experimentalphysik Brandenburgische Technische Universität Cottbus, Karl-Wachsmann-Allee, 03044, Cottbus — ²IHP/BTU JointLab Cottbus, Karl-Wachsmann-Allee, 03044, Cottbus

Using a femtosecond laser as the ionization source, a Time-of-Flight Laser Ionization Mass Spectrometer (ToF-LIMS) is explored with respect to its potential for elemental analysis and depth profiling of multi-layered samples, an alternative to the classical SIMS. For this investigation, we used a structure of type Metal-Oxide-Semiconductor (MOS): a layer of high-k dielectric of Pr₆O₁1 grown by Pulsed Laser Deposition (PLD) on Si (100), covered by an aluminum contact layer.
High lateral and depth resolution could be attained by using small laser spot sizes provided by laser fluences below the ablation threshold for a single pulse. The characteristics of the emitted positive ions give valuable information on the layers quality such as composition, stoichiometry, interface constituents, oxidation and aging. By simultaneously monitoring the layers’ ion product yields over a large number of pulses, anti-correlated ion signals revealing sharp interfaces were identified.
Furthermore, we investigated the morphology of the resulting craters by Atom Force Microscopy. The results indicate that by using ToF-LIMS a depth resolution in the nanometer range could be reached.