Properties of Copper Interconnection Layers Deposited by Electroplating Using a Copper Hexafluorosilicate Electrolytic Solution

Abstract

This paper describes the deposition and properties of copper layers electroplated from a newly developed copperhexafluoro-silicate electrolytic solution. A low stress copper layer can be obtained using this electroplatingtechnique, with a stress ratio as defined by Δd/d, as low as 0.0156 in the as-deposited layers. This ratio decreases to 0.0027 and a stress-free layer is formed after annealing at 300°C. This ratio, however, is held at the higher level of 0.019 in layers deposited from the conventional copper sulfate solution. Such stress reduction leads to the deposition of highly (111) oriented layers with low resistivity. For instance, the full width at half-maximum of the Cu(111) X-ray diffraction spectra are 0.42 and 0.57 for this layer and for the conventional copper sulfate copper layer, respectively. The resistivity of the as-deposited layer is 1.8 μΩ cm, and is lower than that of the copper deposited from the copper sulfate solution. Therefore, a low stress, highly (111) oriented and low resistivity copper layer can be produced by this electroplating technique.