During chemical mechanical polishing step in ultra-large integrated circuit manufacturing process, galvanic corrosion may happen between the directly connected Cu and Ru parts. This problem is much severe when the polishing slurry contains KIO4 as the oxidant. This micro-galvanic corrosion could cause surface non-uniformity and defects, such as aggravated Cu dishing and pitting. To clarify the mechanism of the micro-galvanic corrosion, model Cu-Ru samples, with a small Cu disc embeded in a large Ru disc, were prepared and used for investigation of the galvanic corrosion during the exposure to 0.015 M alkaline KIO_4 solutions.
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