超純水のみによる電気化学的加工法の銅ダマシン配線形成プロセスへの応用

概要

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The electrochemical machining in ultrapure water has been applied to copper etch back process in damascene process. This application is expected to have many merits compared to CMP(Chemical Mechanical Polishing) which is the conventional etch back process. For example, process costs and environmental load can be decreased because electrochemical machining in ultrapure water use neither any electrolyte nor slurry which is used in CMP. In this work, patterned or unpatterned copper film deposited on silicon wafers were etched locally (etched area was about 0.8cm^2) and process parameters such as current density, applied voltage, rotating speed of the electrode and distance between specimen and rotating electrode were optimized. Although we had etch pits or fiber marks on etched surfaces in conditions which were not appropriate, flat surface (Ra<4nm) without etch pits and fiber marks were obtained in optimum conditions. A property of decreasing surface topography was also evaluated by etching a narrow pattern (0.7μm-line/spasing) and a wide pattern (20μm-line/spacing) simultaneously. As a result, these two patterns which have 1.2μm-thick difference to be etched were almost flattened simultaneously.
2004-05-05