Investigation on the final polishing slurry and technique of silicon substrate in ULSI

In this paper, the final polishing slurry and polishing techniques are studied, which is based on the investigation of the polishing kinetics process and mechanism of the silicon substrate. The new polishing kinetics process and mechanism are put forward. CMP final polishing slurry used in silicon substrate polishing is also researched, in which the smaller size (ranging from 15 to 20 nm) silica sols is chosen as abrasive instead of large size silica sol (ranging from 50 to 70 nm). The polishing slurry with smaller abrasive and polishing technology effectively reduces the roughness and thickness of the damaged layer resulting from abrasion (commonly about one fourth of the abrasive particle size) and also affords high polishing rate (200 nm/min). The influence of PH adjustment, abrasive size, temperature and flow of the polishing slurry, are also discussed. During CMP of silicon substrate, chemical action is reinforced. After more research, the main ingredients, including organic-alkali hydroxide multi-amine, surfactant and abrasion are chosen preferentially. In a word, the compositive effect that includes smaller particle abrasion (ranging from 15 to 20 nm), high polishing rate (200 nm/min), lower damage, easy washing and higher surface degree of finish, are ultimately achieved by this means of the polishing slurry and polishing techniques in this paper. The final polishing slurry and technology effectively resolve the technique problems, including surface scoring, polishing haze, metal ion contamination and residuary particle. Thereby, IC devices and the rate of final products are markedly improved. (C) 2002 Elsevier Science B.V. All rights reserved.