Chemical Mechanical Polishing

摘要

Chemical mechanical polishing (CMP) is a technology less than two decades old. It was developed at IBM in the mid-1980s as an enabling technology to planarize SiO_2 interlevel dielectric (ILD) layers so that three or more levels of metal could be integrated into a high-density interconnect process. This technology was adapted from silicon wafer polishing. By employing CMP, subsequent structures could be fabricated on a nearly planar surface. The initial application of CMP was ILD planarization, but its application to other areas in the overall semiconductor fabrication sequence followed quickly. The next two major steps put into production were tungsten plug formation and shallow trench isolation (STI). CMP technology enabled the replacement of aluminum interconnects with lower-resistivity copper, because copper cannot be substractively etched in a practical manner. The process of forming a trench for the interconnect and then planarizing it so copper remains only in the trenches is often referred to as damascene processing.