Abstract: A method of forming precisely cross-sectioned electron-transparent samples, includes removing, from a wafer, a chip containing a desired viewing site for analysis. At least one metallic mask is formed on a surface of the chip and over the viewing site using a focused ion beam microscope. Using a reactive ion etching technique, the chip is etched in a direction essentially perpendicular to the surface of the chip to form a thin viewing surface under the metallic mask. The thickness of the thin viewing surface is further reduced using a focused ion beam milling technique, to form an extremely thin electron-transparent sample.