Halite salts as silicon carbide etchants for enhancing CMP material removal rate for SiC wafer

摘要

Silicon carbide (SiC) etchants with a generic formula of MXO₂, where M is an alkali metal, X is a halogen, O is oxygen are disclosed. When mixed with an abrasive powder in an aqueous slurry form, this MXO₂ etchant acts as tribochemical reactant in enhancing the SiC material removal rate during chemical mechanical polishing (CMP). The material removal rates can sometimes go up to a few order of magnitudes, as compared to the slurry without this MXO₂ etchant. Typical metal in the formula MXO₂ are K (potassium) and Na (sodium), X includes Cl (chlorine), Br (bromine) and I (iodine). The whole series of MXO₂ compounds belong to the chemical family of metal halites or ammonium halites. Sodium chlorite, NaClO₂, the simplest and most available member of the halite family, is a typical example. The enhanced polishing rate can be utilized to significantly increase the throughput of CMP operation for non-oxide wafer polishing. The polishing waste water from the CMP process can be treated with ease in the waste water treatment facilities because of the absence of toxic heavy metal ions in the polishing formulations.