Experimental observation of FIB induced lateral damage on silicon samples

Scanning spreading resistance microscopy (SSRM) and scanning capacitance microscopy (SCM) were used to analyze focused ion beam (FIB) induced lateral damage around milled structures on silicon. For this purpose, circular shaped structures were realized, and the influence of the implanted Ga dose (ranging from 1015 to 1017 1/cm²) and of the patterned area dimension (diameters ranging from 1 to 4 µm) on the damage were examined. It is shown that the extension of the lateral damage around FIB milled structures is much larger than the area of the purposely irradiated regions (up to a factor of 5) and increases with both, Ga dose and pattern diameter. Besides, the unique capability of SCM and SSRM techniques for the detection of FIB induced damage is demonstrated. In particular, it is shown that their high sensitivity to low densities of defects allows detecting larger damaged areas compared to Atomic Force Microscopy (AFM) topography maps.