ダブプリズムを用いた接触画像解析に基づくポリシングパッド表面性状の定量評価手法の開発に関する 研究: パッド表面性状と研磨結果の相関関係

摘要

CMP（Chemical Mechanical Polishing）は砥粒を保持したポリシングパッドがクェーハ表面に軽微な擦 過を与えて鏡面を作る高度な平坦化手法として確実に定着し，多岐に亘る応用が提案されている．その 際，ポリシングパッドの表面性状がウェーハの研磨特性に及ぼす影響は大であること，特に研磨中にお けるパッドとウェーハ相互間の接触状態は研磨レートや研磨精度に影響を及ぼす可能性のあることが指 摘されている．そして現在，高性能な次世代デバイスの実現に対応し，安定した研磨精度を確保するた めの一助として，ポリシングパッドの表面性状評価に関する議論が活発化している．%In the polishing process, it is pointed out that both the removal rate and accuracy of the polishing characteristics are affected by the actual contact conditions between the silicon wafer and a polishing pad. Additionally, it is found that the geometric characterization of polishing pad surface texture have a substantial influence on the actual contact conditions. In the previous study, we proposed a new measurement and evaluation method for polishing pad surface texture based on the contact image analysis method using image rotation prism. We have presented the effective measurement parameters in the previous paper that are (1) contact ratio, (2) number of contact points, (3) spacing of contact points and (4) spatial FFT result of a contact image. This paper presents the relationship between these parameters and polishing characteristics. The removal rate of polishing efficiency is measured by a series of polishing test. Polishing accuracy is obtained applying SFQR and ROA method. As a result, it is found that the proposed parameters are efficient in estimating polishing characteristics. Especially, the spacing of contact points and spatial FFT parameters that indicate high correlation results with the polishing characteristics.