Total reflection and grazing emission X-ray fluorescence spectrometry: Assessment of the size of contaminant particles on silicon wafer surfaces

Under conditions of grazing incidence, the development of X-ray standing wave fields above flat and smooth surfaces enables X-ray fluorescence spectrometry in the total reflection mode (TXRF) to provide information about the nature of contamination (particle or film) or even the sizes of particles which are present on silicon wafer surfaces. The capability of TXRF in this area is demonstrated by examples involving the metals Fe and Ni. A complementary method, grazing emission XRF (GEXRF) has proved to be more suitable for the analysis of the light elements since the fluorescence radiation is detected with a wavelength-dispersive system in contrast to TXRF which employs energy-dispersive detection. A GEXRF instrument has been constructed which utilizes a cold electron source as primary radiation. Its use is demonstrated for Al on a silicon wafer surface. As a further step, the use of a special laser plasma X-ray source is proposed in order to increase the primary intensity in a GEXRF arrangement.