3-D Modeling of Wafer Topography's Effect on Chemical Mechanical Polishing Process

Abstract

In this paper, removal rate variation caused by wafer surface topography during CMP is studied based on 3-D solid-solid contact model. The height of the wafer topography is a function of two dimensions (). A new way to calculate the contact pressure between the wafer and the pad during CMP is proposed in the paper. It is found that if the topography of the wafer is represented as a linear combination of , then the contact pressure between the wafer and the pad can also be represented as a linear combination of the same signals with different amplitudes. A broad class of signals can be represented as a linear combination of . So the contact pressure can be obtained easily if the magnitude spectra and phase spectra of the system are known. This new method will be very helpful to establish the model of CMP and specify the polishing parameters during CMP. It can also provide help for getting contact pressure when a rigid surface with complicated topography contact with flat flexible base completely.