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Cu metallization by electrochemical deposition has been implemented in ULSI circuit fabrication for forming interconnects since 1998 . As wafer size increases from 8- to 12-inch，and the Cu seed layer decreases in thickness for every technology node，ohmic resistance of Cu seed layer increases significantly，leading to severe non-uniform deposition of copper film due to a phenomenon called "terminal effect" . A deposited Cu film that has within-film non-uniformity (WFNU，defined as the thickness standard deviation divided by the thickness mean) exceeding 2.5％ fails to meet the requirement for subsequent CMP process . In this report，impact on WFNU from chamber geometryfactors and process parameters was quantitatively evaluated by simulating the growth process of Cu film. WFNU less than 1.0％ was achieved for 3000A Cu film deposited on 350A Cu seed through optimization of chamber design and the deposition process.