Abstract
An atomic force microscope (AFM) was used to simulate the abrasive particles/surface interaction in the chemical mechanical polishing (CMP) process. Lateral forces measurements were performed between a silica particle and a silica wafer at the presence of surfactant dispersants and at pressures close to that exhibited in the CMP. In our previous study we have shown that the surfactant dispersants were effective at stabilizing the slurries but at the same time the material removal rate was negligible. The lateral force measurement reviled that the low removal rate is due to the boundary lubrication provided by the residing surfactant between the particles and the wafer. We showed that is possible to manipulate range in which the boundary lubrication is effective by simply changing the solution conditions as pH and electrolyte concentration. Base on that general founding we tried to push down the lubrication effectiveness limit by adding different type of counterions to the solution. A dramatic increase in the frictional force was found in the presence of multivalent counterions. Polishing test at that slurry conditions showed high material removal rate and at the same time the slurry were stable resulting at good surface finishing.
