Development of a Pad Conditioning Process for Interlayer Dielectric CMP Using High-Pressure Micro Jet Technology

Abstract

Diamond conditioning was compared to an alternative method, namely high-pressure micro jet (HPMJ) conditioning, through a series of interlayer dielectric chemical mechanical planarization (ILD CMP) marathon tests. The two systems were compared individually and in combination on the basis of ILD removal rate (RR), coefficient of friction (COF), and the physical appearance of the pad surface (both on the top areas as well as inside the grooves). Results indicated that diamond conditioning alone was effective in causing RR and COF stability during extended runs, but it could not clean the slurry residues and other by-products from the surface of the pad (especially inside the grooves). Results also showed that HPMJ conditioning was able to effectively clean the pad surface, despite not providing enough energy to abrade the surface of the pad and maintain constant RR and COF during extended polishing. Based on these findings, a new pad conditioning method based on a combination of diamond and HPMJ conditioning was proposed. Results showed that this new method allowed for stable polish results in terms of RR and COF during extended marathon runs, and also yielded substantially residue-free surfaces, which could extend pad life and reduce wafer-level defect.