A method of locating dried residue on a semiconductor wafer in vapor phase decomposition-total-reflection X-ray fluorescence spectrometry by monitoring scattered X-rays

Abstract

Listen

Translate article

Abstract Vapor phase decomposition-total-reflection X-ray fluorescence spectrometry (VPD-TXRF) is used in the analysis of whole-surface trace metal contamination on silicon wafers at a very high sensitivity. In VPD-TXRF, locating the exact position of dried residue is critical for obtaining a reliable analysis. To locate the residue, the fluorescence from the internal element added as standard reference for quantification is most commonly used as a search marker. However, the added internal standard reference sometimes interferes with the determination of analytes. To avoid such interference, we introduce a new method of locating the residue that utilizes the scattered X-rays from it. Basic experiments have shown that scattered X-rays can be used as markers of residue position instead of the fluorescence from an internal standard reference. An x – y –θ-controlled stage has been proven to be preferable in the application of this locating method than an r –θ-controlled stage. The repeatability of our method is the same as that of the conventional internal standard reference method. There are many advantages in our new method: no interference with analytes of interest, speed, and ease of application. In addition, the method is compatible with the conventional internal standard reference method.