Lithographically Patterned Nanowire Electrodeposition: A Method for Patterning Electrically Continuous Metal Nanowires on Dielectrics

• Published in: ACS nano Vol. 2; no. 9; pp. 1939 - 1949
• Main Authors: Xiang, Chenxiang, Kung, Sheng-Chin, Taggart, David K, Yang, Fan, Thompson, Michael A, Güell, Aleix G, Yang, Yongan, Penner, Reginald M
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 23.09.2008
• Subjects: Crystallization - methods; Electric Conductivity; Electroplating - methods; Gold - chemistry; Macromolecular Substances - chemistry; Materials Testing; Molecular Conformation; Nanostructures - chemistry; Nanostructures - ultrastructure; Nanotechnology - methods; Nickel - chemistry; Particle Size; Surface Properties; photolithography; electrodeposition; nanowire; noble metal
• ISSN: 1936-0851; 1936-086X; 1936-086X
• DOI: 10.1021/nn800394k

Lithographically patterned nanowire electrodeposition (LPNE) is a new method for fabricating polycrystalline metal nanowires using electrodeposition. In LPNE, a sacrificial metal (M1 = silver or nickel) layer, 5−100 nm in thickness, is first vapor deposited onto a glass, oxidized silicon, or Kapton polymer film. A (+) photoresist (PR) layer is then deposited, photopatterned, and the exposed Ag or Ni is removed by wet etching. The etching duration is adjusted to produce an undercut ≈300 nm in width at the edges of the exposed PR. This undercut produces a horizontal trench with a precisely defined height equal to the thickness of the M1 layer. Within this trench, a nanowire of metal M2 is electrodeposited (M2 = gold, platinum, palladium, or bismuth). Finally the PR layer and M1 layer are removed. The nanowire height and width can be independently controlled down to minimum dimensions of 5 nm (h) and 11 nm (w), for example, in the case of platinum. These nanowires can be 1 cm in total length. We measure the temperature-dependent resistance of 100 μm sections of Au and Pd wires in order to estimate an electrical grain size for comparison with measurements by X-ray diffraction and transmission electron microscopy. Nanowire arrays can be postpatterned to produce two-dimensional arrays of nanorods. Nanowire patterns can also be overlaid one on top of another by repeating the LPNE process twice in succession to produce, for example, arrays of low-impedance, nanowire−nanowire junctions.