Patent ID: 8512588

Claim:
A method of fabricating a nanoporous membrane filter having an array of uniform nanopores of a desired pore size, comprising: providing a thin-film multilayer having a (100)-oriented single crystal silicon layer adjacent a substrate layer, said single crystal silicon layer of a predetermined thickness which etches anisotropically with an anisotropic wet chemical etchant selective to silicon over a material of the substrate layer; forming a hard mask layer over the single crystal silicon layer; depositing photoresist over the hard mask layer; using at least two interferometrically-arranged lasers of the same wavelength to interferometrically define in the photoresist an etch pattern comprising an array of unit patterns each having a predetermined width that is substantially a function of the desired pore size and the predetermined thickness of the single crystal silicon layer; transferring the etch pattern from the photoresist to the hard mask layer to expose select portions of an upper boundary surface of the single crystal silicon layer; anisotropically etching the exposed select portions of the upper boundary surface of the single crystal silicon layer with the anisotropic wet chemical etchant until a lower boundary plane of the single crystal silicon layer is reached so that an array of inverted frusto-pyramidal etch cavities are formed each having a frustum floor at the lower boundary plane that is substantially equal in width to the desired pore size; and etching a section of the substrate layer with an etchant that is selective to the substrate material over silicon to remove the frustum floor of the etch pits at the lower boundary of the single crystal silicon layer and thereby form the array of uniform nanopores of substantially the desired pore size.