Control of the Micro-Defects on the Surface of Silicon Wafer in Chemical Mechanical Polishing

The final polishing of silicon results in the irresistible formation of micro-defects (i.e., particle residues and scratches) on the surface. In view of this problem, the synergistic effect of surfactants and water-soluble polymers in inhibiting the micro-defects on the silicon surface was studied in this paper to improve the wettability of the slurry and reduce the micro-flocculation of abrasive particles. The results showed that the total number of residual particles (>= 0.06 mu m) on the polished surface was reduced from 24,784 to 277 with the adsorption of cationic polyacrylamide (CPAM) and fatty alcohol polyoxyethylene ether (AEO-9). The water-soluble polyvinylpyrrolidone (PVP) polymer could coat on the SiO2 abrasives, inhibit the flocculation of abrasive particles, avoid scratches on the silicon surface and further reduce the number of residual particles (>= 0.06 mu m) to 67 on the polished surface. Furthermore, a contact angle analyzer was used to characterize the wettability of the components in the slurry, and a large particle counter was used to analyze the changes in the number of large particles in the slurry component. Finally, a mechanism of surfactants and a water-soluble polymer combined system was proposed to suppress the micro-defects on the surface of the silicon wafer.

Automated summary

This study investigates the synergistic effect of surfactants and water-soluble polymers to improve the wettability and reduce micro-flocculation of abrasive particles on the silicon surface. The results show that the adsorption of cationic polyacrylamide and fatty alcohol polyoxyethylene ether can reduce the number of residual particles, while water-soluble polyvinylpyrrolidone can coat the abrasives and further reduce the residual particles. Contact angle analysis and particle counting were used to evaluate the changes.