超LSIプロセスにおける平坦化CMP技術と装置の開発(第2報)

パッドドレッシング均一化技術の開発

抄録

Pad conditioning is one of significant subjects to keep constant polishing rate and polishing uniformity for CMP(Chemical Mechanical Polishing). To achieve constant pad conditioning, the following three factors are indispensable: (1) Formation of stable contact condition between pad and conditioner, (2) Real time pad condition, (3) Conditioning uniformity within the whole area of the pad. In order to meet their factors, pad conditioner with abrasives on retainer surface, which was termed `conditioning retainer', has been developed to realize stable polishing performance for CMP. The conditioning retainer carrying out simultaneously both pad conditioning and wafer polishing has a great deal of stiffness enough to keep horizontal contact to the pad against continuous friction resistance during pad conditioning. In addition, surface of the double layer pad conforms to surface of the conditioning retainer, so that contact configuration between conditioning retainer and pad has been kept to be constant. For uniform pad conditioning, the shoulder slope shape was formed on the assist pad to compensate the excessive wearing on the pad edge. The shape relieving polishing pressure at the pad edge corresponds to retainer trajectory density on the pad. The measure resulted in uniform pad wearing and the continuous uniform polishing profile.