Effect of conditioning downforce and pad break-in time on pad surface micro-texture

The effect of conditioning downforce during pad break-in, and its impact on the evolution of pad surface micro-texture was investigated. Two different conditioning downforces were used to break-in pads. Pad samples were extracted after certain break-in times and analyzed for their topography and contact area using confocal microscopy. Results showed that the pad-wafer contact area and contact density decreased with conditioning downforce. Break-in at the higher conditioning downforce helped in reaching faster stabilized values of the analyzed micro-texture parameters. The evolution of these parameters was different for the two different downforces, however as break-in time increased past 30 minutes, mean summit height and mean summit curvature began to approach approximately the same value. These results indicated that, for the particular disc used in this study, a change in the magnitude of downforce during pad break-in caused a change in break-in time and stable values for some micro-texture parameters. However, a change in the magnitude of downforce during break-in only resulted in a change in break-in time for other micro-texture parameters. The work underscored the need for conducting such tests with different conditioners in order to develop a better understanding of the role downforce plays on the evolution of the micro-texture.