Copper CMP planarity control using ITM

The new interconnect technology, based on copper damascene processes that is soon to enter production, provides a new challenge for production use of in-line metrology. Copper CMP is a challenging process, both due to the varied chemical and physical properties of the materials on the wafer surface, as well as the within-lot and within-wafer incoming metal thickness nonuniformity. However, the role and requirements of integrated metrology for copper CMP have not been completely determined yet. This paper describes new capabilities designed to meet this challenge of copper polish process monitoring. Experimental results, showing measurements of metal-loss and barrier-material residue thickness, obtained with various Reflected Light Spectroscopy systems, are presented and discussed. Also discussed are different schemes of monitoring the polish process, as well as a comparison between the erosion and metal line thickness results obtained with Reflected Light Spectroscopy, to those of a surface profiler