Chemical Mechanical Planarization of Copper Interconnections by Manganium Oxide Slurry

摘要

Deep dishing and erosion are serious problem in conventional chemical mechanical planarization (CMP) specifically when hard barrier layer is used as polishing stopper. This polishing is major origin of dishing and erosion. Dishing free CMP process can be attained by following procedures. 1) Increase of removal rate in barrier layer: Removal rate increases from 1.5 nm/min in polycrystalline TaN barrier layer to 70 and 77 nm/min in the polishing of a-TaN and TaSiN barrier layers employing MnO_2 slurry. 2) Reduction of the removal rate of copper layer Removal rate of electroplated copper layer deceases to 210 nm/min in the polishing by MnO_2 slurry. This rate decreases to 77 nm/min with the doping of 10 % additive in this slurry. Since thin anti-oxide layer is formed at the Cu surface during the polishing by this slurry, removal rate ratio of Cu/TaSiN barrier layer can be reduced markedly. Dishing free CMP can be achieved by the CMP at a rate ratio of 1.0.