TXRF Metrology Tools

TXRF spectrometers are widely used to measure contamination in the semiconductor fabrication process. TXRF technique allows non-destructive analysis for most all elements (Na~U) in the periodic table. TXRF spectroscopy is possible due to the property of X-rays as they irradiate the surface of a wafer. Each material has a unique critical angle. If the incident angle of the X-rays is above the acute angle, the X-rays penetrate the surface deeply; if the incident angle is smaller than the critical angle, total reflection occurs. In the total reflection condition, fluorescence X-rays will occur only from contamination on the surface, and the substrate material will not add background noise to the measurement. The penetration depth of the incident X-rays under the conditions of total reflection is theoretically around 5 nm, and thus TXRF is classified as a surface analysis technique.