X-ray mirrors on flexible polymer substrates fabricated by atomic layer deposition

Abstract Atomic layer deposition (ALD) techniques were used to fabricate W/Al 2 O 3 superlattices with high X-ray reflectivity on flexible Kapton® polyimide and polyethylene naphthalate (PEN) polymer substrates. Reflectivities of 78% and 74% at λ = 1.54 A were measured for 6-bilayer W/Al 2 O 3 superlattices on Kapton® polyimide and PEN, respectively. These excellent X-ray reflectivities are attributed to precise bilayer thicknesses and ultrasmooth interfaces obtained by ALD and smoothing of the initial polymer surface by an Al 2 O 3 ALD layer. The conformal ALD film growth also produces correlated roughness that enhances the reflectivity. These W/Al 2 O 3 superlattices on flexible polymers should be useful for ultralight and adjustable radius of curvature X-ray mirrors.