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Sputtering with focused ion beams (FIB) is an important technique for patterning in the semiconductor technology down to nanoscale size (i.e., optimization of tips for scanning probe microscopy (SPM), device modification, or nanolithography). However, the highly energetic ions induce severe damage in the target material. For silicon, this usually even leads to an amorphization of the processed area and its surrounding. As normally no high temperature anneal is performed after FIB processing, damage remains and may lead to a low performance or even a failure of affected devices. Because the focused ion beam is Gaussian-shaped, not only the purposely exposed area has to be considered but also the tail of the distribution may lead to serious damage outside of the directly processed region, as even a small amount of damage strongly influences electrical properties like charge carrier mobility. In this work, we successfully demonstrate that Scanning Spreading Resistance Microscopy (SSRM) is a highly sensitive technique for the electrical characterization of the FIB induced damage in silicon by gallium ions (30 keV). For this purpose, p-type silicon samples were irradiated with different Ga doses and currents. Subsequently the samples were analyzed by SSRM and SPM in the tapping mode. In the irradiated regions the smallest investigated dose of 2xE14 cm-2 leads to an increase in volume (swelling) due to implanted ions of about 1.1 nm and a structural change of the irradiated silicon. Increasing the dose up to 5xE15 cm-2, sputtering dominates, leading to an effective removal of target material. Furthermore, with increasing dose the SSRM signal increases from about 7xE8 to 2xE10 Ω. It is expected that the intensity of the SSRM signal depends on the degree of amorphization which will be discussed and compared to High Resolution (HR)-TEM images. For SSRM, the detected region of damage due to the beam tail is much larger compared to the swelling area determined from topography measurements (for the highest dose this region extends about 650 nm for SSRM and about 250 nm for SPM). The results clearly demonstrate that SSRM is a very fast and sensitive tool for high-resolution detection of ion beam induced damage, allowing for savings in preparation times and costs. |