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Copper and nickel electrodeposition into ordered macropores prepared in p-type silicon has been studied in aqueous solutions containing cupric and nickel ions, respectively. When a macroporous silicon template was cathodically polarized in 0.1 M cupric sulfate solution, copper was deposited preferentially at the pore bottom in the dark, whereas the deposition was found to proceed not only at the pore bottom but also partially on the pore wall under the back side illumination. In contrast, the deposition of nickel in 0.1 M nickel sulfate solution was not possible in the dark, while deposition occurred uniformly on the entire surface of the pore wall under the back side illumination. Dissolution of silicon templates by the alkaline etching process led to the formation of copper microrods and nickel microtubes. The deposition behavior of both metals was compared and this discrepancy was discussed.

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PACS 68.37.Hk, 81.07.Bc, 82.45.Vp Copper deposition into ordered macroporous silicon prepared in p-type substrates was investigated by immersion plating and electrochemical deposition in an aqueous solution containing Cu 2+ ions. When the sample was immersed in 0.1 M CuSO 4 solution at the open circuit potential, Cu crystallites are clearly observed at the top surface and inside the pores. The deposition of Cu oxidizes the substrate simultaneously to SiO 2 . On the other hand, the potentiostatic deposition in the dark revealed that Cu deposits preferentially at the pore bottom and propagates towards the top surface. Furthermore, when the substrate was illuminated under cathodic potential, the Cu deposition was enhanced mainly at the top-surface and around the pore walls. The different deposition behavior was compared and discussed.

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The formation process of ordered macropores in a prepatterned p‐type silicon wafer was investigated. FE‐SEM observation focusing on the early stage of the pore growth clarified the two‐step process of macropore formation, whose first step was isotropic pore expansion from prepared etch pits and the second was anisotropic growth in the depth direction. Investigation using different etch‐pit patterns revealed that ordered macropores with constant diameters were obtained when the spacing of etch pits was 3–8 μm, while the spacing of 2 μm resulted in the pore‐wall collapse. The diameter and the wall thickness of macropores showed a tendency to decrease with decreasing the spacing of prepared etch pits, which could not be explained only from the width of the space‐charge region. The resistance distribution in a silicon substrate was proposed as a parameter playing a crucial role in determination of the wall thickness. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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