A NEW APPROACH IN NONDESTRUCTIVE CHARACTERIZATION AND X-Y PROFILOMETRY OF COATINGS

A scanning electron microscope equipped with an x‐ray detector has been used to characterize the thickness and elemental composition of coating on substrates. The proportionality between the x‐ray signal intensity and the thickness, t, of the coating has been established experimentally and explained by applying a formalism similar to that used in Auger analysis. The thicknesses under investigation range from that of Auger (∼ 3–4 nm) to a fraction of a micron. The accuracy of thickness determination (±5%) is mainly governed by the statistics when the operating conditions are optimized. The x‐ray profiles and images obtained by incident electron beam scanning allow a rapid evaluation (with two‐ or three‐dimensional representations) of the lateral thickness and compositional changes of the coatings. At the same time, the use of the ‘scatter diagram’ technique improves their quantitative interpretation. The lateral resolution (better than 1 μm) and limitation of the technique are discussed. Both academic and practical examples are used to illustrate its application. Copyright © 1990 John Wiley & Sons Ltd.