Physics and tribology of chemical mechanical planarization

The physical and tribological attributes of the chemical mechanical planarization (CMP) process are reviewed. Kinematic analysis of a CMP polisher is described, which can be applied in establishing tribological models. These models elucidate the lubrication regimes at the workpiece/polishing pad interface at the macroscale in order to examine the regional uniformity in the amount of material removed. At the micro/nanoscale, the material removal and planarization mechanisms are mainly discussed from the theoretical and modeling perspective together with experimental verification provided using scanning probe microscopy (SPM) techniques. Selected CMP applications in the field of micro/nanoelectromechanical system (MEMS/NEMS) are also highlighted in conjunction with fabrication processes and tribological challenges at the sub-nanometer scale.