Improvement of In-line SCD metrology on BEOL Copper CMP erosion layers for 65nm technology node logic production application

摘要

Erosion Cu (Copper) interconnect monitor of BEOL (Back End of Line) CMP (Chemical Mechanical Polishing) is a series of key steps for producing high yield Integrated Circuits. For years, ultrasonic was applied to Cu in-line measurement. However, do we have an alternative? In this paper, new solution by the theory of scatterometry was proposed, it is called SCD (Scatterometry CD) metrology. To demonstrate the performance of SCD, multiple layers of Logic 65nm production, from Metal 2 to Metal 5, were developed by SCD and point to point matching with baseline tool were qualified. Furthermore, DOE (Design of Experience) have been employed to verify correlation among SCD, ultrasonic and TEM (Transmission Electron Microscopy). Finally, SCD is proven to be the reliable, high throughput and non-destructive solution of Cu line monitor.