A scatterometer capable of plane-of-incidence bidirectional reflectance distribution function (BRDF) measurements at extreme ultraviolet wavelengths between 58.4 and 121.6 nm has been developed. This instrument has a lower measurement limit of approximately 10<sup>−5</sup> sr<sup>−1</sup>, and it is able to accommodate angles of incidence between 10° and 75°. The scatterometer can measure scatter to within 1.5° of the specular beam, and the scatter angle can be measured to within 0.1°. The design, analysis, and performance of this instrument are discussed here. Scatter data, in the form of BRDF measurements, are presented for a 3000-line/mm grating and a flat chemical vapor deposited diamond sample.
© 1997 Optical Society of America
Michael P. Newell and Ritva A. M. Keski-Kuha, "Extreme ultraviolet scatterometer: design and capability," Appl. Opt. 36, 2897-2904 (1997)