Investigation of Dressing Characteristics of Single Crystal Diamond in CMP

Abstract

Diamond conditioners, or dressers, are commonly used to dress polishing pads that are applied to the chemical mechanical polishing of silicon wafers for integrated circuits. Although the diamond conditioner has regular distribution diamond grits, they differ in shape and can be oriented differently because the shape of diamond grits is generally cubo-octahedral. Therefore, the dressing behaviors on the polishing pad are unpredictable. In this work, the fundamental characteristics of dressing are investigated by a single crystal diamond with various shapes (each resulting in point-cutting, line-cutting, and face-cutting), a rake angle of-50°, and cutting faces in the (100) and (111) planes. For the purpose of analysis, plowing ratio is defined as the sum of the areas of the two side ridges divided by the groove area. This ratio can be used to evaluate the contribution of plowing and cutting actions from the dressing. Experimental results reveal that a groove with ridges on both side walls is formed as the diamond is moved over the pad. The profile of the scratch correlates with the shape of the diamond. In summary, cutting dominates when point-cutting is responsible for the dressing. On the contrary, plowing plays a major role with respect to line-cutting. The cutting action tends to dominate when the dressing is completed by face-cutting a (111) plane. Alternatively, the wear tends to be dominated by the plowing action if the dressing is conducted via face-cutting a (100) plane.