Rule to determine CMP polish time

摘要

A simple method for calculating the optimum amount of HDP deposited material that needs to be removed during CMP (without introducing dishing) is described. This method derives from our observation of a linear relationship between the amount of material that needs to be removed in order to achieve full planarization and a quantity called "OD for CMP density". The latter is defined as PAx(100-PS) where PA is the percentage of active area relative to the total wafer area and PS is the percentage of sub-areas relative to the total wafer area. The sub-areas are regions in the dielectric, above the active areas, that are etched out prior to CMP. Thus, once the materials have been characterized, the optimum CMP removal thickness is readily calculated for a wide range of different circuit implementations.