Effect of frictional force vector on delamination in Cu/low-k integration

We investigated the relationship between the direction of frictional force vector and the delamination probability in the chemical mechanical polishing (CMP) process of Cu/low-k damascene structures. To obtain the direction of the frictional force vector, the relative velocity vector between the polishing pad and the wafer with corresponding direction was simulated. The test element group (TEG) pattern designed to evaluate the delamination properties was used for measurement of delamination probability. As a result, the delamination probability of a wafer was low when polished by the scan-type CMP operating with directional frictional force in comparison with the conventional-type CMP. The delamination probability was even lower in the area where the directivity of frictional force was strong. From these results, it is concluded that the directivity of frictional force vector reduces the delamination probability.