Characteristics of the kinetics of periodic structures CMP for a nonlinear pressure dependence of the polishing rate

Abstract

For the kinetics of the chemical mechanical polishing (CMP) of wafers containing periodic metal–dielectric structures, a model is developed and theoretically investigated with the use of contact mechanics methods for the nonlinear pressure dependences of the polishing rate. In the steady-state regime, expressions for the dishing effect, which is characterized by the difference in the depths of the polishing metal and dielectric strips, are analytically derived and investigated. The specific characteristics of this effect, which are observed for different kinds of nonlinearities of the polishing rate depending on the pressure and the relative rotation velocity of the pad and wafer, are analyzed. Particularly, it is shown that, under certain conditions, the steady-state regime may be nonunique (the bistability effect).