Full Sequence Electrochemical-Mechanical Planarization

The electrochemical removal of both bulk and remaining copper is referred to as full-sequence ECMP (FS-ECMP), and it has been investigated by many researchers [20,32]. In FS-ECMP the entire wafer has to be contacted to the anode throughout the polishing process. A conductive polishing pad provides a path for current to flow even when copper islands are formed and allows for residual copper to clear. The research focus has been on developing polishing 

Unlike in the ECMP process described earlier, the initial conductivity of the liquid between the wafer and the pad is not required. As a matter of fact, a conductive solution actually lowers the planarization efficiency as shown in Fig. 11.24. Similar to ECMP, high planarization efficiency can be obtained at 

FIGURE 11.22 Linear relationship between removal rate and current density in an ECP-DI process. The removal rate is independent of pressure and linear velocity of the platen (from Ref. 32). 

FIGURE 11.23 Planarization performance on the 10- and 100-pm copper lines with 50% metal density for an ECP-DI polishing (from Ref. 32). 

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Several people in the IBM Semiconductor Research and Development Center including the alliance partners helped in reviewing this chapter for clarity and consistency and provided valuable input. The author would also like to thank the Applied Materials team who has been working on electrochemical-mechanical planarization for their continuous support during the development of the hybrid ECMP as well as for providing their inputs on the recent developments for full-sequence ECMP. In addition, the author gratefully acknowledge to the kind contribution from Manabu Tsujimura of Ebara on the comparison of ECP, ECP-DI, ECMP, and CMP. 

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