Chatter Reduction in a Chemical Mechanical Planarization Pad Conditioner
Equipment used for polishing silicon wafers employ polish pad conditioning devices to maintain and enhance material removal rates during chemical mechanical planarization, CMP. Extensive sliding contact of a diamond studded strip over a topologically complex polishing pad gives rise to stick-slip noise generation called chatter. A program of modal and harmonic response analysis was coupled with vibration testing to assess the feasibility of a damping scheme to reduce chatter. Although significant assumptions were used to avoid modeling a complex and non-linear contact interface, acceleration measurements show that ANSYS gave good guidance on the direction of the most significant vibrations, the primary natural frequency of the system, and the effectiveness of damping to reduce the amplitude of the displacement. Quantitative and qualitative assessments show that the chatter noise was virtually eliminated.