Effect of Kinematic Parameters and Their Coupling Relationships on Global Uniformity of Chemical-Mechanical Polishing

In this paper, the kinematic analysis and numerical calculation are used to discuss the effect of the kinematic parameters on the final polishing result of typical rotary chemical-mechanical polishing (CMP) equipment. The relative velocity distribution and the sliding distance distribution are calculated based on the kinematic analysis. Especially, the coupling relationships between the kinematic parameters are investigated and discussed. And two parameters of the sliding distance nonuniformity (SDNU) and the sliding distance nonuniformity within concentric circles (SDNU-cc) are proposed and calculated to evaluate the global uniformity of the sliding distance and to reveal the coupling relationships between the kinematic parameters. The results suggest that the relative velocity distribution and the sliding distance distribution are significantly affected by the coupling effects of the basic motions of CMP system; the SDNU is mainly affected by parameter alpha, which represents the coupling relationship between the rotary motions of the wafer carrier and the polishing platen; the SDNU-cc is mainly affected by parameter k'(T0)(alpha k(T0)), which represents the coupling relationship between the reciprocating motion and the rotary motion of the wafer carrier; alpha approximate to 1 and alpha k(T0) > 2 are proper for better polishing uniformity in real CMP process.