Some Methods To Reduce Micro Scratch Defect For Via Contact Tungsten Chemical Mechanical Planarization Process

Chemical Mechanical Planarization (CMP) is a very important and essential part of modern integrated circuit fabrication process, and along with CMP process side-effects such as scratch defect appears inevitably. Contact Tungsten CMP (CT W CMP) process emphasizes both microcosmic topography and surface planarity. Scratch defects of via CT W CMP would induce yield loss by resulting in contact bridge failure. Several factors contributing to the formation of CMP scratch defect under mass production condition is generally introduced in this work, then particularly this paper shares a relationship between slurry particulates’ size and count distribution by different layer of potted slurry and moreover indicates how slurry settling time during its storage affects this distribution, which explains the fact that the longer the slurry is aged and the higher layer of a slurry drum is used, the less scratch defects pattern wafers may suffer. Finally, an effective method to break such fact by alternating a new CMP polishing pad combined with a certain tungsten CMP slurry is also discussed here, supporting the opinion that polishing pad design has a great influence on the wafer microcosmic topography thanks to a better performance of the polishing byproduct’s removal, with these methods by wafer micro scratch defect count was reduced by 89% on 28nm logic product wafers.