High Spatial Resolution Imaging of Dopants and Impurities for Semiconductor Device Using NanoSIMS

In order to respond to development for electrical packages in these days, required techniques in analytical tools have been sophisticated noticeably. For elemental analyses, Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy (SEM-EDX) has been available for device inspection taking advantage of the high spatial resolution. However, it has become an issue that SEM-EDX has a downside of poor sensitivity for impurities at lower concentration levels. Under such circumstances, NanoSIMS has found to be a promising tool for elemental analyses at smaller areas or imaging making use of the higher spatial resolution and high sensitivity. NanoSIMS can be applied to various materials such as resin, metal and ceramics, which takes various essential parts of electrical packages, and available as a tool which can provide exclusive information for these packaging materials. For film with filler and ABS resin, not only main component but unintended impurities in each manufacturing process were clearly observed by NanoSIMS. As for metal, a titanium-based alloy was investigated by NanoSIMS and SEM-EDX. From imaging of NanoSIMS, carbon, silicon and sulfur distribution in the alloy was depicted sharply, especially sulfur was found to be located along grain boundary, which could not be observed by SEM-EDX. Impurities in inorganic grain of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SiO}_{2}$</tex> was examined assuming the usage of ceramic grain for package materials. In spite of small area of less than 5 micrometer, impurities contained in the grain at lower concentration levels were precisely detected and one of these was also quantified by using reference materials, which can not be realize by SEM-EDX or conventional SIMS.