Particles, Processes, and Planning: Synergies to Improve CMP Yield
The slurry is the most critical and expensive part of the process and determines the selection of all other chemicals and equipment. The interactions are complicated, with the possibility that improvement in one aspect might come at a detriment to another and not result in the expected yield.
As fabs face ever more stringent performance requirements, slurries keep changing and advancing. The mature slurry chemistries that worked well for copper metallization at the 22-nm node are not compatible with newer metals like cobalt, ruthenium, or molybdenum. Manufacturers are reformulating slurries—engineering new abrasive particles and blending in new additives to fine-tune the slurry performance.
As the slurry changes, so must the cleans. Cleans must be formulated to be compatible with the wafer surface material while removing all organic residue, slurry abrasive, and metal contamination. The choice of brushes also affects the clean process.
The entire system must support the slurry. That includes filters installed throughout the process, including those used in the clean step. System design—tubing, fittings, and process monitors—also affects how well a slurry performs.
Sourcing the slurry, filters, components, and monitoring tools from a single supplier makes it much easier to ensure they are all compatible with one another. Doing so streamlines process development, improves cost-effectiveness, and reduces risk. As a result, cost of ownership goes down, defect rates decrease, and yield remains high.
This white paper explores the entire CMP process, including post-CMP cleaning, to identify potential sources of contamination and propose synergistic solutions to minimize yield risk.