Polishing characteristics of micron particles aggregated by nanosilica

Polishing characteristics of micron particles aggregated by nanosilica

Blog Article

Colloidal silica slurry has been widely used in mirror finishing of various microelectronic materials, including Si wafer.However, in the last decade, there has been a tendency to replace the polishing slurry with fixed-abrasive pads because of environmental issues related to HALTER/BRIDLE BAG WITH 3 HOOK RACK the use of slurry and poor finishing surface shape accuracy.Unfortunately, the fixed-abrasive pad is still unsatisfactory for both material removal rate and finishing surface quality.Therefore, various silica abrasives added into fixed-silica pads for polishing Si wafer were investigated in this study.

Both loose and fixed abrasive polishing experiments were performed.Instead of conventional nanosilica abrasive, the micron spherical particle aggregated by nanosilica (hereafter, aggregate silica) was proposed as an abrasive of fixed-silica pad, and were compared with micron natural crystal silica abrasive and micron spherical fused silica particle.Experimental results demonstrated that the nano-aggregating structure of aggregate silica with a mean diameter of about 5um has approximately 100 times higher specific surface area than the natural and fused silica abrasive, and can easily absorb more [-OH] onto the aggregate silica surface, which is approximately 5 times when each of them is added to the alkaline aqueous solution at pH 12.Thus, a strong chemical removal effect was observed.

This condition caused not only higher material removal rate but also pedal plate better finishing surface roughness, which can be comparable to that of colloidal silica slurry with 10 nm to 20 nm particle size (5 wt%, pH 10.5).The chemical removal effect can also be enhanced by increasing nanopore volume of aggregate silica.