CMP slurries and pads: Characteristics
Why one oversized particle can scratch a wafer to scrap
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.What matters is removal rate, selectivity between films, within-wafer uniformity and, above all, defects: a few oversized particles can scratch and kill dies. Particle size distribution, purity and stability are tightly specified.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Abrasive particle size | tens to about 100 nm, with tight control of the large-particle tail (indicative) | Large particles cause scratches | Indicative |
| Selectivity | oxide to nitride ratio set by additives in ceria STI slurries (indicative) | Lets polishing stop on target layers | Indicative |
| Metal contamination | ppb levels (indicative) | Contamination degrades devices | Indicative |
Commercial grades
- Ceria STI and ILD slurries
- Copper bulk and barrier slurries
- Tungsten slurries
- Cobalt, molybdenum and ruthenium slurries
- Poly and nitride slurries
- Hard and soft polyurethane pads
- Pad conditioners and post-CMP cleans