AVS 47th International Symposium
    Material Characterization Thursday Sessions
       Session MC-ThA

Paper MC-ThA6
Elemental Mapping of Sub-µm Particles and Structures by LASER-SNMS and TOF-SIMS

Thursday, October 5, 2000, 3:40 pm, Room 207

Session: Evolving Technologies in Surface Analysis
Presenter: F. Kollmer, Physikalisches Institut der Universitaet Muenster, Germany
Authors: F. Kollmer, Physikalisches Institut der Universitaet Muenster, Germany
R. Kamischke, Physikalisches Institut der Universitaet Muenster, Germany
R. Ostendorf, Physikalisches Institut der Universitaet Muenster, Germany
H. Bender, Materials and Components Analysis Group IMEC
A. Benninghoven, Physikalisches Institut der Universitaet Muenster, Germany
Correspondent: Click to Email
Sputtering-based surface mass spectrometry as SIMS or Laser-SNMS combines high sensitivity with high lateral resolution, provided a high fraction of sputtered particles is ionized and a finely focused primary ion beam is applied. For sub-µm characterization the transformation probability of a surface atom into an ion should be optimized. The large fraction of sputtered neutrals and their efficient laser-postionization result in high Laser-SNMS sensitivities. The use of a time-of-flight (TOF) mass spectrometer guarantees parallel mass registration at high transmission. We report on recent results of TOF-SIMS and Laser-SNMS characterization of sub-µm particles. The analyzed particles include Al@sub 2@O@sub 3@, Fe@sub 2@O@sub 3@ and CeO@sub 2@ with diameters down to 15 nm. On the base of these results we compared both techniques one with the other and in addition with Scanning Auger Microscopy (SAM). The know how gained from these investigations was applied to supported metal catalysts and other sub-µm structures such as magnetic heads. By applying a combined TOF-SIMS/Laser-SNMS instrument, a direct comparison of both techniques was possible. The use of a 30 keV finely focused Ga@super +@ source and a time-of-flight instrument guarantees high lateral (@>=@80 nm) and mass resolution at high transmission. For nonresonant postionization an excimer-laser (193 and 248 nm) was applied. SAM characterization was carried out in a VG 350 F instrument. We determined useful yields, as a measure of sensitivity, for a variety of mono-elemental metal samples. The obtained useful yields in the order of 10@super -2@ (SNMS) and 10@super -3@ (SIMS) allow to analyze structures well below the spot size of the primary ion beam. We found higher elemental sensitivities for TOF-SIMS and especially Laser-SNMS compared to SAM. Quantification was possible by the use of SAM and Laser-SNMS, the latter additionally allows to estimate the total amount of material in a particle.