Abstract
The suitability of multi-wave X-ray reflectometry, in which X-ray reflectivities measured with multiple X-ray waves are optimized simultaneously by the least squares method, was investigated for layered structure analysis of spin-valve films. It was found that Co-Kβ, Cu-Kβ, and Cu-Kα1 lines are suitable for analysis of a spin-valve film based on estimation of the reflective intensity at each boundary of the film. Next, a 3-wave method using these 3 X-rays and a 2-wave method using Co-Kβ/Cu-Kβ or Co-Kβ/Cu-Kα1 lines were examined. Structural parameters such as the film thickness, density, and interface width can be determined more accurately for both the 3-wave and 2-wave methods than for a 1-wave method using the Co-Kβ line. In 3-wave reflectometry, the errors, defined as 3 times the standard deviation, in determining the film thicknesses for ∼1 nm CoFe and ∼2 nm Cu films were ±0.04 nm and ±0.02 nm, respectively. The errors in 2-wave reflectometry were slightly larger, being around ±0.05 nm.
