Freestanding Alumina Membrane by Double-Layer Anodization |
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Authors: | Xingqun Jiang Mishra N. Turner J.N. Spencer M.G. |
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Affiliation: | Sch. of Electr. & Comput. Eng., Cornell Univ., Ithaca, NY; |
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Abstract: | A novel method has been developed for fabricating full or partial freestanding anodic alumina. In our method a sacrificial metal layer is introduced between an Al film and a Si3N4 substrate. A freestanding alumina film at wafer scale is successfully achieved by anodizing the double metal layer, during which the alumina is spontaneously stripped off the Si3N4 substrate due to the anodic oxidation of the sacrificial layer. The barrier oxide of the alumina film is effectively removed either by H3PO4 dissolution or by CF4 reactive ion etching. The freestanding alumina film is utilized as a contact mask to transfer its nanoporous pattern to a Si substrate. By patterning the sacrificial metal layer with contact lithography, a partial freestanding alumina film is successfully achieved on the silicon chip, producing a unique micro/nanofluidic channel. Compared with previous techniques, the method reported here is advantageous for its simplicity and flexibility |
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