Mapping of non-planar surfaces and film conformality by alpha-particle energy loss spectroscopy

A method of mapping 3D periodic structures in the micron- and submicron range is presented. The method consists of implanting alpha-emitting nuclei close to the surface and measuring the emerging alpha-particles at various directions. Information about surface topography is then obtained from the number of alphas that are observed directly by the detector. Measuring the shift in energy due to deposition of overlayers permits the analysis of the conformality of films deposited on complex periodic structures. Typical applications include the characterization of gratings in semiconductor layers fabricated during the production of laser structures and of quantum wires. An experimental example for periodic V-grooves etched in GaAs is shown.