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 electroplating technique, with a stress ratio as defined by ⌬d/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 ͑111͒ oriented layers with low resistivity. For instance, the full width at half-maximum of the Cu͑111͒ 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 ⍀ cm, and is lower than that of the copper deposited from the copper sulfate solution. Therefore, a low stress, highly ͑111͒ oriented and low resistivity copper layer can be produced by this electroplating technique.

To improve ultrapure water, the additional effect of HF in pure water was investigated. Both formation of native oxide on the Si wafer surface and generation of viable cells in pure water can be prevented by using pure water containing HF on the order of parts per million instead of conventional pure water. Moreover, by using PFA or PTFE as a pipe material, pure water containing HF which was not contaminated by metal ions and viable cells can be fed to point of use without a circular line such as a conventional pure water feeding line.

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