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Microprocessors could be made even smaller if the copper in their circuits
were smooth, say researchers at the Naval Research Laboratory in Washington DC.
Microchip components are often built up in layers on copper films. But if the
copper surface is rough, the first layer of the component has to be thick, so
that it creates a smooth surface for the other layers. Researcher Shu-Fan Cheng
takes the rough edges off copper with nitric acid and uses benzotriazole to
prevent the fresh copper surface from oxidising. “This new technique doesn’t use
abrasive slurries such as alumina, which generally create scratches,”…