Graded barrier of metal line copper back end

The graded barrier layer the has complex metal/metal salt-metal structure, e.g., Ta/TaxN1-x/TaN1-x/Ta structure, capable of being used to replace traditional barrier layer in copper metallizing process. The graded barrier layer may be formed in chemical or physical vapor deposit process. In the chemical vapor deposit process, the graded barrier layer is formed through utilizing easy-to-control reactant gas and regulating gradually the ratio ratio between Ta element and N element. In the physical vapor deposit process, the graded barrier layer is formed through depositing several TaxN1-x layers with different composition, and subsequent heat circulation step, such as metal alloying step, to make Ta element and N element distributed gradually. The present invention has the advantages of easy-to-control technological condition, strong adhesion between the mesolayer hole and metal, etc.