Low-kV EDX Surface Analysis Can Replicate Metal Oxidation Trends of XPS for Semiconductor Package Assembly.

Low-kV energy-dispersive X-ray (EDX) spectroscopy offers rapid quantitative information that correlates to the oxidation and corrosion of metals. In semiconductor package assembly, metal interfaces are the connection points for subsequent layers, so oxide growth must be monitored and minimized to ensure device reliability. X-ray photoelectron spectroscopy (XPS) is the textbook standard technique for comparing surface oxidation states. In this article, we show that at 2-3 kV, low-kV EDX can replicate XPS trends for Ni, Cu, Sn solder bumps, and Au land grid arrays (LGAs). There is no practical loss in sensitivity compared to XPS, and significant advantages including better imaging, a simpler learning curve for operators, faster data collection, and deeper, more forgiving penetration. When metal composition is understood and the focus is on oxidation trending among similar samples, it may not be necessary to cover the entire periodic table or calculate each oxidation state. Low-kV EDX deserves more attention for fast surface analysis.