Chemical Mechanical Polishing Slurry for Tungsten in ULSI With Large Particle Size Colloidal Silica Nano-Abrasive

Silica sol nano-abrasives with large particle are prepared and characterized by TEM, PCS and Zeta potential in this paper. Results show that the silica sol nano-abrasives about 100nm are of higher stability (Zeta potential: −65mV) and narrow distribution of particle size. And then alkali CMP slurries for tungsten containing self-made silica sol nano-abrasives are prepared and applied. CMP results show that the removal rate has been improved to 367nm/min and the RMS of surface roughness has been reduced from 4.4nm to 0.80nm. In sum, one kind of alkali slurry containing 100nm silica sol for tungsten CMP is studied.