A feature scale model for chemical mechanical planarization of damascene structures

Abstract

A physically based feature-scale model for chemical mechanical planarization (CMP) of damascene structures is presented. The model incorporates important process parameters such as slurry hydrodynamics, pad properties and the wafer-pad contact. Both chemical and mechanical components of CMP are captured in the present model and are described by separate kinetic parameters. Abrasive effects can be incorporated empirically in the kinetic parameters. The model simplifies the wafer-pad contact problem by assuming effective pad properties, dominated by contributions from pad asperities, rather than those of the bulk pad material. Model results justify this assumption and are compatible with step height evolution, dishing and erosion measured with single-level copper-oxide test structures. Dishing is found to be strongly dependent on line width, while erosion depends mainly on the slurry properties. The framework presented in this paper can be utilized for modeling polishing a variety of materials, with different CMP process conditions.