Preserving CMP Slurry Health Through Proper Handling and Preventive Maintenance

摘要

As Chemical Mechanical Polishing (CMP) has become widely practiced in the manufacture of integrated circuits, it has brought about a dramatic change in the meaning of the word "contamination" in liquid chemical distribution systems. Conventional high purity chemical distribution systems typically handle single-component chemicals, such as sulfuric acid, and attempt to eliminate all other materials-metallic, ionic, and particulate. While high purity chemical may have particle contamination levels of a few particles per liter of size 100 nanometers, CMP slurry contains ～10~(18) particles per liter of the same size. Thus CMP slurry contains enormous amounts of material that every other chemical and distribution system in the fab tries to eliminate. To complicate the issue of maintaining slurry health, many factors can cause changes to the slurry, which will have a (usually negative) effect on its handling and polishing properties. This presentation will cover many of the typical problems encountered during slurry packaging, shipping, on-site handling, blending, and bulk delivery. Slurry degradation phenomena, such as decomposition, loss of volatile components, and agglomeration will occur - even under the best of circumstances. However, optimized systems and proper handling can help minimize the extent of damage and lengthen the timeframe over which it occurs. Preventive maintenance is required in slurry delivery systems to avoid unscheduled interruption of supply to the polisher or accelerated decline in the quality of slurry. While improvements in slurry and slurry delivery equipment are constantly being made, slurry users must accept some compromises in system uptime, preventive maintenance and variability in slurry homogeneity. Finally, teamwork with all suppliers in the CMP slurry chain is critical to maximize the benefits from the CMP process.