As microelectronic devices continue to shrink, submicrometer‐sized contaminants pose a serious threat to semiconductor yields and performance—and thereby to the profits of the nearly $200 billion a year industry. Chemical analysis of these tiny particles can suggest remedies for avoiding contamination by helping to pinpoint its sources. One of the most successful microchemical analysis tools combines electron microscopy with spectroscopic analysis of x rays excited in the target impurity by the microscope's electron beam. Unfortunately, the choice of x‐ray detector has traditionally involved a trade‐off between energy resolution and speed. So the semiconductor industry—where time equalsa lotof money—has often had to supplement spectrometry with educated guesswork. Now, John Martinis, Kent Irwin, Gene Hilton and David Wollman, working at the National Institute of Standards and Technology facility in Boulder, Colorado, have developed an x‐ray detector that they hope will remove some of that guesswork.