Method and apparatus for the detection of light elements on the surface of a semiconductor substrate using x-ray fluorescence (XRF)

Abstract

A method and apparatus are presented which provide non-intrusive detection of atoms of light elements (atomic numbers 3-13) on a surface of a semiconductor substrate using X-ray fluorescence (XRF). The present technique may be economically performed routinely on manufactured products. The method includes producing a monochromatic X-ray beam comprising X-ray photons with energy levels operably chosen to cause only atoms of light elements to emit secondary X-ray photons. The monochromatic X-ray beam is then focused onto a circular exposed region on the surface of the semiconductor substrate, the circular exposed region having a diameter ranging from about 0.5 mm to about 10.0 mm. Secondary X-ray photons emitted by atoms of light elements in the exposed region on the surface of the semiconductor substrate are directed to at least one X-ray detector. Each X-ray detector is aligned to receive secondary X-ray photons from a single light element, and is illuminated for a predetermined amount of time. The number of secondary X-ray photons detected by an X-ray detector in a predetermined amount of time is directly proportional to the number of atoms of a corresponding light element on the surface of the semiconductor substrate. The apparatus includes a high-power X-ray source, a first collimator, a first multilayer crystal, a focusing capillary, a second collimator, a second multilayer crystal, and at least one X-ray detector.

Dependencies are inferred from the claim text.