Study On CMP Nano-Slurry And Technology

Since the technology node of IC developed to 0.25micron, as unique global planarization technology, chemical-mechanical polishing (CMP) has been the IC key process technology. With the continuously shrinking of feture size, the requirements to CMP slurry and technology become more and more rigorous. In order to meet the requirement to CMP of substrate and GST thin film in IC process, the following works were done in this paper: preparation and purification of colloidal nano-abrasives with large size; fine CMP slurry and technology for Si substrate; the CMP, electrochemistry and wet etch process of GST for CRAM and so on.First, both colloidal silica nano-abrasives with large size and control technique of growing of nanometer particle are systematically studied, which are also urgent problems in IC process. A series of preparation techniques of colloidal silica nano-abrasives are achieved. Based on the analysis of growing mechanism of monodisperse colloidal silica nano-abrasives, different low cost preparation processes including ion-exchange of sodium silicate and hydrolysis of silicon with catalyst were studied. Though the new process including atmosphere evaporation and steam water control, colloidal silica nano-abrasives with different size (30～120nm) were got. After the purification of colloidal silica nano-abrasives, the content of metal ion is less than 100ppm. In order to prepare high pure abraives for IC s lurry, the hydrolysis of TEOS was done. Based on the optimization of process, the high pure abrasives with large size (60～160nm) were obtained, and the content of metalion was reduced to the level of sub-ppm.Based on the analysis of main effect of every component in slurry, the new polishing slurry for Si substrate was made up. The effect of abrasive size, abrasive concentration, accelerant and surfactant on polishing rate and surface were discussed. As a result, new polishing slurry was a chieved, which was of high polishing rate and high planarization. Comparing with the slurry from Japan, removal rate of Si with the slurry self-made was increased by 40% (697nm/min Vs 500nm/min), and its surface roughness was improved at...