Effectiveness of dilute HF based formulations in selectively removing copper oxide (CuOX) films with respect to copper and dielectric films has been investigated. Key solution variables studied include HF concentration, dissolved oxygen level and pH. Improved CuOX/Cu selectivity has been achieved under deaerated conditions. Deaerated solution containing 1000:1 HF (pH3) provides CuOX/Cu selectivity of ~50:1 and CuOX/low-k dielectric (Carbon Doped Oxide) selectivity of ~15:1. Conditions under which copper can be passivated during cleaning in dilute HF have been explored using electrochemical polarization studies and Electrochemical Quartz Crystal Microbalance (EQCM).