On-chip microscopic corrosion, originating from contact of dissimilar metals, can cause serious reliability issues for integrated circuits and microelectromechanical devices. A new micropattern corrosion screening method combined with Tafel plots were employed to study Cu bimetallic corrosion in acid and base solutions relevant to the chemical-mechanical planarization process. The results demonstrated that Cu corrosion on Ru is much more severe compared to Cu corrosion on Ta substrates. Tafel plots confirm the nobility trend of Ru > Cu > Ta. The micropattern corrosion study shows the Cu bimetallic corrosion depends on specific chemicals and bimetallic contacts. Strong complexing ligands like NH3 combined with energetically favorable Cu/Ru bimetallic contact promote faster Cu corrosion under alkaline conditions (9 a parts per thousand currency sign pH a parts per thousand currency sign 11.4). Micropattern corrosion screening was shown to be useful in identifying the metastable surface layer during Cu corrosion and determining the optimal benzotriazole concentration for Cu corrosion inhibition.