Topography-sensitive copper deposition in supercritical solutions

Topography-sensitive deposition, a preferential growth mode in a narrow concave feature, of copper in supercritical solutions is reported. Experiments were carried out in supercritical carbon dioxide at 13 MPa with a maximum temperature of 230 degrees C, using bis(diisobutylmethanate)copper (Cu(dibm)(2)) as a precursor. Cu was preferentially deposited in narrow cylindrical features with a diameter less than 100 nm. Copper deposits were mostly rod-like and single-crystalline. In larger features deposition occurred within the inside corner of the features. Nonmetallic residues were also found at locations having a small curvature. Through different visualization experiments, the residues were identified as an unreacted precursor. From these observations, it was concluded that the topography-sensitive deposition proceeds through a capillary condensation of the precursor that is dissolved in the supercritical carbon dioxide at a high concentration, following the conversion to metallic copper. (C) 2009 Elsevier B.V. All rights reserved.