Phase change observation in reflection multilayers by total electron yield and reflection spectra

Abstract

Precise optical elements for use in the extreme ultraviolet region are necessary for controlling both the uppermost layer thickness and the reflection phase in a reflection multilayer system. In this study, a phase value corresponding to both the uppermost layer thickness and the reflection phase was derived from the reflectance and total electron yield (TEY) intensity. Mo∕Si multilayers were fabricated on a silicon wafer with various thicknesses of the uppermost Mo layer. Phase values obtained from the reflection and TEY measurements were found to change in accordance with increases in the thickness of the uppermost Mo layer and a concomitant change in the reflection phase.