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In semiconductor metallization processes, the galvanic corrosion of metals should be controlled to improve the process integrity. Refractory metals such as tantalum and tantalum nitride ͑TaN x ͒ are widely used as a barrier metal to prevent the copper ͑Cu͒ metal from diffusing into the dielectric layers. In this study, the galvanic effect between the Cu seed and the TaN x film, which is deposited with different nitrogen ͑N 2 ͒ gas flow rates was investigated using chemical mechanical polishing slurries. It was found that the galvanic corrosion of the TaN x films decreased whereas the galvanic corrosion of the Cu seed increased as the N 2 gas flow rate increased. The whole Cu corrosion rate was higher than that of the TaN x films because the intrinsic corrosion of the Cu seed dominated the overall Cu corrosion rate in the acidic slurry, but for the TaN x films the galvanic corrosion dominated. This study also proposed a model to reveal the galvanic effect between the Cu seed and various TaN x films.In sub-130 nm semiconductor device manufacturing, copper ͑Cu͒ has been used as the interconnection metal as a replacement for aluminum because the Cu metal has higher electromigration resistance and lower resistivity. Different from the metal-etching patternization in the aluminum metallization process, the Cu metal lines are produced by the damascene process including the deposition of diffusion barriers and Cu metals and the removal of overburden metals by chemical mechanical polishing ͑CMP͒. 1-13 For the Cu metallization, a barrier layer is necessary to prevent Cu metal from diffusing into dielectric layer. The materials used as barrier layers should not only be thin enough to reduce effective metal resistance but also have compatible adhesion between the Cu metals and dielectric layers. 14-22 In addition, good step-coverage is necessary for the barrier deposition to form a uniform layer along the feature surfaces and corners. Tantalum and tantalum nitride ͑Ta/TaN x ͒ films have been widely used as the diffusion barriers for Cu metallization because of their excellent chemical and thermal stability. The physical properties of TaN x films deposited with different nitrogen ͑N 2 ͒ gas flow rates have been widely investigated in prior literatures. [22][23][24][25] Some researchers have investigated the roles of the nitrogen content on the mechanical properties, microstructures, and electrical characteristics of the TaN x barriers. 7-9 As the N content in the TaN x films increased, the barrier property against the Cu diffusion was improved by blocking Cu diffusion paths, but the film resistivity increased in the meanwhile. Our previous study has reported that as the N 2 flow rate increased from 0 to 10 sccm, the phase of the TaN x gradually transformed from ␤-Ta to body-centered cubic-Ta. Further increase in the N 2 flow rate from 10 to 24 sccm resulted in the phase transformation of the TaN x films to hexagonal Ta 2 N. Finally, the face-centered cubic-TaN phase composed mainly of an amorphous phase was observed when the ...

The composition of the plating electrolyte is important in a copper (Cu) electroplating process. The consumption rate of bis(3-sodiumsulfopropyl disulfide) (SPS) has a strong correlation with the electroplating current density. The decomposition of SPS is relative to the electroplating charge and to the age of the Cu anode. The cathodic current density improves SPS breakdown, and it increases the generation of by-products resulting from SPS decomposition. The aged bath is examined using potentiodynamic polarization and electrochemical impedance spectroscopy. The aged bath helps increase cupric ion reduction because the concentration of cupric ions increases with time after Cu electroplating. The SPS species reacted with cuprous ions to produce the Cu-accelerator complex, which increased the depolarization effect.

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