A finite element analysis(FEA)model is developed for the chemical-mechanical polishing(CMP)process on the basis of a 12-in five-zone polishing head.The proposed FEA model shows that the contact stress non-uniformity is less dependent on the material property of the membrane and the geometry of the retaining ring.The larger the elastic modulus of the pad,the larger contact stress non-uniformity of the wafer.The applied loads on retaining ring and zone of the polishing head significantly affect the contact stress distribution.The stress adjustment ability of a zone depends on its position.In particular,the inner-side zone has a high stress adjustment ability,whereas the outer-side zone has a low stress adjustment ability.The predicted results by the model are shown to be consistent with the experimental data.Analysis results have revealed some insights regarding the performance of the multi-zone CMP.
