In 1989, the chemical–mechanical polishing (CMP) method was developed by Davari et al.for global planarization of the interlayer dielectrics

The development of chemical–mechanical polishing (CMP) has become important for multilevel interconnection technology because it is the only method that allows global planarization (i.e., a flat surface across the whole wafer). It also offers other advantages, including reduced defect density and the avoidance of plasma damage (which would occur in an RIE-based planarization system).

Process of CMP

The CMP process consists of moving the sample surface against a pad that carries slurry between the sample surface and the pad. Abrasive particles in the slurry cause mechanical damage on the sample surface, loosening the material for enhanced chemical attack or fracturing off the pieces of surface into a slurry where they dissolve or are swept away. The process is tailored to provide an enhanced material removal rate from high points on surfaces. Mechanical grinding alone may theoretically achieve the desired planarization, but is undesirable because of extensive associated damage to the material surface. There are three main parts of the process: (1) the surface to be polished; (2) the pad, which is the key medium enabling the transfer of mechanical action to the surface being polished; and (3) the slurry, which provides both chemical and mechanical effects.