Polishing characteristics of different glass films

Chemical Mechanical Polishing (CMP) is becoming a mainstream technology for the planarization of dielectrics at various process levels. Widely different types of glass films are now routinely processed using CMP techniques. In this work, the polish rates using an aqueous silica based slurry for thermally grown SiO₂, plasma deposited SiO₂, and boro-phospho-silicate glasses have been compared. A polishing mechanism based on the concentration of water in the glass is proposed. It is also shown that the presence of phosphorous changes the polishing mechanism compared to undoped glasses and the rate increase due to phosphorous is much greater than that due to boron.