Advanced Process Control in Dielectric Chemical Mechanical Polishing (cmp)

The decrease in device dimensions is placing extremely tight constraints on many aspects of the CMP process. We outline four key areas that will provide significant steps toward attaining this level of control. In particular, we discuss the need for improved in-line surface topography metrology, and show that that high resolution profilometry appears to meet this need. We demonstrate the need for new metrics to monitor and control CMP planarity, and present evidence which suggests current methods of step height measurement are insufficient for this task. The use of in-situ sensors and on-line metrology is shown to provide significant improvement in our ability to monitor and control post-CMP film thickness. The use of in-situ sensors in compensating for incoming thickness variation is outlined. Finally, the use of on-line metrology for accurate monitoring and control of specific locations is shown.