FILM THICKNESS MEASUREMENTS OF SIO2 BY XPS

The preferred XPS methodology for measurement of SiO2 film thickness on polished silicon surfaces is discussed. A precise measurement of the photoelectron attenuation length was made using nuclear reaction analysis (NRA) to calibrate the film thicknesses. Anodic oxide films on Si, which are very reproducible in thickness, are used as test samples. Appropriate corrections for the problem of adventitious carbon are shown. Under some conditions, the phenomenon of photoelectron diffraction has a significant effect on the measurements, and improvements to the precision by rotating the sample about the normal during data acquisition are demonstrated.