This month we are going to deviate from Mark Lund's normal discussion and talk about one of the practical problems that must be considered when using an x-ray detector on a scanning electron microscope to solve real-world problems.

Several years ago I worked in the analytical laboratory of a major semiconductor manufacturer. One day a process engineer came into the lab and asked us to develop an analytical method to determine the amount of copper in an aluminum film on a silicon wafer. The levels of copper would be somewhere between 0.5% and 1.0%. He gave me a sample, saying that he didn't know the exact concentration of copper but was certain that it was at least 0.5%.