The use of X-Ray Reflectometry for single film thickness analysis in GMR multilayer stacks

The performance of giant magnetoresistive (GMR) sensor heads critically depends on the physical thicknesses of all functional layers involved in the so-called Spin-Valve stack, and consequently has to be controlled via very accurate thickness analysis methods. In this paper we demonstrate that X-Ray Reflectometry (XRR) analysis of the fnll GMR multilayer stack provides an absolute means to extract selected single film thicknesses with Angstrom accuracy. Secondly, we present XRR data recorded from special reduced layer sequences which allow to determine the deposition rates of Co, NiFe, Cu and Ru with an error of better than 0.04 Hilsec. We further show how for the analysis of GMR full stacks the XRR technique can be usefully combined with X-Ray Fluorescence (XRP) to measure the individual thicknesses of all layers.