Submicron metal etch integration study

Abstract

Recent progression toward low pressure metal etching has been driven primarily by the reduction in spacing between features and the corresponding increase in aspect ratio of the areas to be etched. Key limitations of etching small feature spaces (< 0.6 micrometers ) include the aspect ratio (> 2:1) and pattern density variations between isolated and dense lines. This paper addresses the development and integration of a production worthy sub-micron metal etch process. The work performed focused on statistical design of experiments to determine the critical factors controlling the etching of small metal line spaces along with the overall characteristics of the final post metal etch process. Full integration included analysis of photo resist strip, passivation and corrosion control. The process as designed, contrary to common practice, cleared small space geometries first followed by the clearing of open field metal. This approach eliminates the common pattern density dependency of metal etch and provided a simplified process for implementation into manufacturing.