Pattern effects, resulting from different metal removal rates on various feature designs in copper chemical mechanical polishing (Cu CMP), can be reduced in an abrasive-free slurry formulated with HNO3 and benzotriazole (BTA). In the slurry, non-native Cu-BTA adlayer is formed instead of native metal oxide as surface passivation layer on a Cu surface, and it benefits nonlinear Cu removal rate as function of down force. Moreover, by controlling the down force, the Cu removal rate can be independent of down force resulting in the reduction of pattern effect. (C) 2005 The Electrochemical Society.