Study On CMP Slurry Of ULSI Copper Interconnection Layer

Along with the feature size of IC becoming smaller and smaller, the depth of focus of photoetching technique is becoming shorter and shorter. The requirements to surface flatness also turn to more rigorous than before. The increasing of silicon wafer diameter and layers of multi-level metal interconnects bring CMP technology an unprecedented challenge. Although the CMP technology is considered as the most applied and irreplaceable method for realizing local and global planarization during the manufacturing process of IC, but because the complexity of copper CMP mechanism, there are still some problems such as worse technique stability, low rate of finished products and productivity. In the process of CMP, the copper CMP slurry make a dual function of chemical erosion and mechanical lapping, have an important influence to the surface quality. Now, copper CMP slurry still has the problems of metal ion contamination, low material removal rate in alkalescent environment and so on. Studying the material removal mechanism thoroughly of copper CMP and developing high performance CMP slurry, as two doable approaches to resolve problems that mentioned above, has become the researching focuses in the CMP technology field recently.The subject of this paper is the study of slurry prescription suitable for copper interconnection layer in ULSI manufacturing. For reducing metal ions content, improving material removal rate, the selection of slurry prescription and optimization is studied through many theories and experiments. Meanwhile, the material removal mechanism has also been discussed. At last, the ingredients and prescription of slurry is found, and the slurry is made with well properties.The researching route of this paper is: Firstly, the CMP mechanism has been studied in this paper. The factors that influence the polishing quality mostly have been found. At the same time after considering the main problems of copper slurry at present, the projects of selecting ingredients and optimizing prescription have been established. Secondly, the functions of main ingredients of slurry have been analyzed. The single factor experiments of every ingredients of slurry have been carried out on the UNIPOL1502 lapping polishing machine and CP-4 polishing machine. Through the experiment, the main ingredients of slurry, such as abrasive, organic alkali, oxidant etc, have been selected that suitable for the copper polishing. Lastly, on the basis of research before, the optimization experiments of parameters and ingredients have been carried out, finally got a sort of high efficiency and high performance alkalescent copper slurry.The study of this paper provides a kind of systemic researching methods and a group of useful experimental conclusions for improving the polishing quality of alkalescent copper slurry, increasing the material removal rate and how to optimize the slurry description. It has significant meaning for developing the metal interconnection layer planarization technology for Ultra Large Scale Integrate Circuit.