Effect of various CVD-coated conditioning disc designs and polisher kinematics on fluid flow characteristics during CMP

A novel experimental technique utilizing UV-enhanced fluorescence was developed and used to measure fluid film thicknesses and general flow patterns during conditioning on a polishing pad. The method was successfully applied to several case studies for analyses of how conditioners with different working face designs (i.e. complex vane, full-face and partial-face), in conjunction with different platen angular velocities, affected fluid transport. In general, for all discs types, fluid across the pad followed similar trends where films were thickest near the wafer track center and thinnest near the pad edge (measurements showed a thickness range of appx. 0.5 to 1.1 mm). For all discs, the time for the film thicknesses to reach steady-state increased in proportion to the distance away from the pad center (times ranged between 12 and 62 s). The full-face conditioner consistently produced the thinnest films and reached steady-state the fastest. In contrast, the complex vane conditioner created the thickest films and took longest to reach steady-state. The work demonstrated the significance of understanding and visualizing the mechanisms that can contribute to fluid transport during CMP and how our novel technique could contribute, in the near future, to a greater understanding of fluid transport during in-situ conditioning.