Real-time polishing pad stiffness control using magnetically controllable fluid

摘要

A method of CMP polishing of a semiconductor wafer is described that includes using a polishing pad on a platen/table with the polishing pad including a sub-pad containing pockets of magnetorheological fluid. The stiffness of the sub-pad is controlled by selectively applying a magnetic field at selective pockets containing magnetorheological fluid to change the viscosity of the magnetorheological fluid. The changing stiffness increases the polishing rate of the pad in the areas of the magnetic field.