Freestanding Alumina Membrane by Double-Layer Anodization

• Published in: IEEE transactions on nanotechnology Vol. 6; no. 3; pp. 328 - 333
• Main Authors: Xingqun Jiang, Mishra, N., Turner, J.N., Spencer, M.G.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.05.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aluminum; Aluminum oxide; Anodic alumina; Anodizing; Applied sciences; Biomembranes; Channels; Contact; contact mask; Cross-disciplinary physics: materials science; rheology; double-layer anodization; Electronics; Etching; Exact sciences and technology; freestanding; Lithography; Materials science; Microelectronic fabrication (materials and surfaces technology); Molecular electronics, nanoelectronics; Nanobioscience; Nanocomposites; nanofluidic channel; Nanomaterials; Nanoporous materials; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Other topics in nanoscale materials and structures; Physics; sacrificial metal layer; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Semiconductor films; Silicon; Silicon nitride; Substrates; thin film; Transistors; Aluminium oxide; nanofluidic channel; Patterning; Silicon nitride; sacrificial metal layer; Contact process; Nanoporous materials; Flexibility; Nanofluidic device; freestanding; Thin film; Nanoelectronics; double-layer an-odization; Microelectronic fabrication; Reactive ion etching; Anodic alumina; Anodizing; contact mask; Double layers; Wafer; Sacrificial layer
• ISSN: 1536-125X; 1941-0085
• DOI: 10.1109/TNANO.2007.894870

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 Si 3 N 4 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 Si 3 N 4 substrate due to the anodic oxidation of the sacrificial layer. The barrier oxide of the alumina film is effectively removed either by H 3 PO 4 dissolution or by CF 4 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