Ultrahigh x-ray reflectivity from W∕Al2O3 multilayers fabricated using atomic layer deposition

W ∕ Al 2 O 3 multilayers were fabricated using W and Al2O3 atomic layer deposition (ALD) to produce x-ray mirrors. The x-ray reflectivity from an optimized W∕Al2O3 multilayer was 96.5%±0.5% for the first-order Bragg peak at λ=1.54Å. The ultrahigh x-ray reflectivity is attributed to the precise bilayer thicknesses and ultrasmooth interfaces obtained from ALD film growth. The self-limiting ALD surface chemistry prevents randomness during film growth and produces conformal deposition with correlated roughness that enhances the x-ray reflectivity.