Direct Measurement of Planarization Length for Copper Chemical Mechanical Planarization Polishing (CMP) Processes Using a Large Pattern Test Mask

We have used a large pattern test mask and a specific arrangement of structures on a wafer for direct measurement of an average planarization length for copper chemical mechanical polishing (CMP) processes. We propose new minimum, maximum, and average planarization length definitions, based on up and down area measurements as a function of trench width. The average planarization length is useful for qualitatively comparing the planarization capability of copper CMP processes. We have also performed several experiments that show how the average planarization length depends on polish process settings such as down force and relative speed, as well as on consumables such as pad and slurry.