Benefits of microscopy with super resolution

Abstract

Transmission Electron Microscopy developed from an imaging tool into a quantitative electron beam characterization tool that locally accesses structure, chemistry, and bonding in materials with sub Angstrom resolution. Experiments utilize coherently and incoherently scattered electrons. In this contribution, the interface between gallium nitride and sapphire as well as thin silicon gate oxides are studied to understand underlying physical processes and the strength' of the different microscopy techniques. An investigation of the GaN/sapphire interface benefits largely from the application of phase contrast microscopy that makes it possible to visualize dislocation core structures and single columns of oxygen and nitrogen at a closest spacing of 85 pm. In contrast, it is adequate to investigate Si/SiO x N y /poly-Si interfaces with incoherently scattered electrons and electron spectroscopy because amorphous and poly crystalline materials are involved. Here, it is demonstrated that the SiO x N y /poly-Si interface is rougher than the Si/SiO x interface, that desirable nitrogen diffusion gradients can be introduced into the gate oxide, and that a nitridation coupled with annealing increases its physical width while reducing the equivalent electrical oxide thickness to values approaching 1.2 nm. Therefore, an amorphous SiN x O y gate dielectric seems to be a suitable substitute for traditional gate oxides to further increase device speed by reducing dimensions in Si technology.

Critical review of the current status of thickness measurements for ultrathin SiO2 on Si Part V: Results of a CCQM pilot study

“…This is not possible in the bright-field images so, instead, the extremity of the crystalline region is taken as the interface. 105 Finally, a 1 nm thick band of amorphous carbon was detected on top of the 2 nm SiO 2 layer. This sample proved very difficult to cross-section and, not surprisingly had poor adhesion to the Ti capping layer.…”

Advanced electron crystallography through model-based imaging

“…In order to unscramble the structure-properties relation, experimental characterization methods are thus required that can locally determine the unknown structure parameters with sufficient precision (Spence, 1999;Muller & Mills, 1999;Springborg, 2000;Olson, 2000). A precision of the order of 0.01-0.1 Å is needed for the atomic positions (Muller, 1999;Kisielowski, Principe et al, 2001). If we can determine the type and position of the atoms with sufficient precision, the atomic structure can be linked to the physical properties.…”

Phase imaging and the evolution of a gold-vacuum interface at atomic resolution

“…What is seen, which is quite remarkable, is the displacement of whole columns of gold atoms (typically containing three to nine atoms) at the gold-vacuum interface. The results presented here are relevant for studies of interfaces, defects and nano-particles for which significant structural change can consist of the removal, displacement or rearrangement of only a few atoms [8][9][10][11][12][13][14] .…”