SI/B4C NARROW-BANDPASS MIRRORS FOR THE EXTREME-ULTRAVIOLET

We report the results of extreme-ultraviolet reflectance measurements and structural characterization of multilayer mirrors made by sequential sputter deposition of Si and BIC. Compared with Si/Mo multilayers, Si/B4C have a much narrower bandpass (delta lambda) and better off-peak rejection but lower peak reflectance (Re). Mirrors with three different designs gave the following results: R(0) = 0.275 and delta lambda = 0.31 nm at 13.1 nm and normal incidence; R(0) = 0.34 and delta lambda = 1.1 nm at 18.2 nm and 45 degrees; and R(0) = 0.30 and delta lambda = 2.0 nm at 23.6 nm and 45 degrees. These multilayers exhibited excellent stability on annealing at temperatures up to 600 degrees C.