CHARACTERISTICS IN CHEMICAL-MECHANICAL POLISHING OF COPPER - COMPARISON OF POLISHING PADS

A systematic study of Cu CMP in terms of the effect of polishing pad p roperties on the process characteristics has been performed. The IC 10 00 and IC 1000/SUBA IV polishing pads were compared with regard to the polish rates, across-wafer uniformity, planarity and pattern sensitiv ity of the CMP process. Polishing with the IC 1000/SUBA IV pad, a bett er uniformity and higher polish rates were achieved. No differences in the pad influence on the geometry effects (Cu dishing and SiO2 thinni ng) have been found, which can be explained with the same near-surface layer affecting the interaction between pad and wafer. The hardness o f the IC 1000 allows the material to planarize across wide Cu areas wi th minimal dishing and good planarity, but it is also essential that t he SUBA IV bottom layer of the IC 1000/SUBA IV polishing pad improves the resilience and compressibility of the pad and enhances the global uniformity in the polish removal. It was demonstrated that uniform mat erial removal during polishing is one of the fundamental concerns in t he CMP technique affecting the tolerances deliverable by the CMP proce ss.