MNT-ERA ProjektCombined SIMS-SPM instrument for high sensitivity and high resolution elemental 3D analysis (SIMS-SPM)

• Forschungsstelle: INNOSUISSE
• Projektnummer: 9635.2;5 PFNM-NM
• Projekttitel Englisch: MNT-ERA ProjektCombined SIMS-SPM instrument for high sensitivity and high resolution elemental 3D analysis (SIMS-SPM)

Kurzbeschreibung (Deutsch)

MNT-ERA ProjektCombined SIMS-SPM instrument for high sensitivity and high resolution elemental 3D analysis (SIMS-SPM)

Kurzbeschreibung (Englisch)

MNT-ERA ProjektCombined SIMS-SPM instrument for high sensitivity and high resolution elemental 3D analysis (SIMS-SPM)

Abstract (Deutsch)

State-of-the-art SIMS instruments allow to produce 3D chemical mappings with excellent lateral (50 nm on Cameca¿s NanoSIMS 50) and depth (1nm range) resolutions. Considerable efforts are currently spent to further improve the spatial resolution of SIMS instruments. On the one hand, the development of new ion sources with an increased brightness allows producing smaller spot sizes and thus increased lateral resolutions. On the other hand, new ion optics permitting lower impact energies of the primary ions reduce the dimensions of the collision cascades in the sample and hereby improve the depth resolution.The obtained 3D resolution is however often much worse than what could be expected considering the instrumental performances. As a matter of fact, the sample surface presents an initial roughness which leads to an uncertainty on the depth scale. Moreover, this roughness changes during the ion bombardment as the local sputtering yields depend on parameters such as the local angle of incidence of the ion beam, the crystal orientation, ¿Complementary in-situ Atomic Force Microscopy (AFM) mappings of the surface roughness of the sample would allow correcting the SIMS images with respect to the artefacts mentioned above. A careful image overlay procedure would ensure exact alignment of the resulting AFM images with the area analyzed by SIMS. As a consequence, the total eroded depth could be determined as a function of the lateral position within the sputter crater, thus allowing an independent depth scale calibration on each pixel of the imaged area. Combining the mass spectral data processed this way with the topography information from the AFM images, it would be possible to reconstruct the true spatial distribution of species within the investigated sample volume.

Abstract (Englisch)

State-of-the-art SIMS instruments allow to produce 3D chemical mappings with excellent lateral (50 nm on Cameca¿s NanoSIMS 50) and depth (1nm range) resolutions. Considerable efforts are currently spent to further improve the spatial resolution of SIMS instruments. On the one hand, the development of new ion sources with an increased brightness allows producing smaller spot sizes and thus increased lateral resolutions. On the other hand, new ion optics permitting lower impact energies of the primary ions reduce the dimensions of the collision cascades in the sample and hereby improve the depth resolution.The obtained 3D resolution is however often much worse than what could be expected considering the instrumental performances. As a matter of fact, the sample surface presents an initial roughness which leads to an uncertainty on the depth scale. Moreover, this roughness changes during the ion bombardment as the local sputtering yields depend on parameters such as the local angle of incidence of the ion beam, the crystal orientation, ¿Complementary in-situ Atomic Force Microscopy (AFM) mappings of the surface roughness of the sample would allow correcting the SIMS images with respect to the artefacts mentioned above. A careful image overlay procedure would ensure exact alignment of the resulting AFM images with the area analyzed by SIMS. As a consequence, the total eroded depth could be determined as a function of the lateral position within the sputter crater, thus allowing an independent depth scale calibration on each pixel of the imaged area. Combining the mass spectral data processed this way with the topography information from the AFM images, it would be possible to reconstruct the true spatial distribution of species within the investigated sample volume.