Filling of mesoporous silicon with copper by electrodeposition from an aqueous solution

Copper filling into mesopores formed in highly doped p-type silicon was investigated. When the copper electrodeposition was carried out at a very small constant current density (−6.4 μA cm−2), the mesopores with 4 μm depth were filled with copper continuously from the bottom to the opening. When the electrodeposition current was set at an absolute value twice as large as in the above condition, the isolated particles were electrodeposited in the mesopores. The depth also affected the filling behavior. The pores with 8 μm in depth were not continuously filled with copper even in the condition at which the pores of 4 μm in length were completely filled. Electrodeposition behavior in mesopores was also simulated using a simple model. The numerical simulation suggested that the diffusion-limited electrodeposition could be achieved in mesopores at a very small current, at which the diffusion-limited condition had never been realized on a planar electrode.