Modeling and control of material removal and defectivity in chemical mechanical planarization

Abstract

Chemical Mechanical Planarization (CMP) is a necessary step in semi conductor manufacturing. Since its introduction it has been able to provide better local and global planarization. CMP has found applications in emerging technologies such as shallow trench isolation, damascene technologies. As device size shrinks CMP has become increasingly prominent. CMP process has been analyzed at different length scales such as particle, feature and wafer scales. Models have been developed for each scale. The models initially have been deterministic, accounting for material removal by a single isolated particle. These models predicted the quality control parameters such as material removal rate and planarization at global scales. Recently, probabilistic models have been developed to describe material removal rate from particle scale. However there do not exist models which capture the interaction between parameters at different length scales. The focus of this thesis is to develop a multi-scale model that considers the interaction between parameters at different length scales. The interaction between macroscale property pH of the slurry on the micro-scale phenomenon such as particle agglomeration has been studied. Interaction between pad asperity distribution and particle diameter distribution has also been studied. In the existing probabilistic models the effect of asperities on the material removal has been studied assuming that the pad asperities are supported on a rigid base. In this thesis the pad cellular structure under the asperities is considered to predict scratch performance and material removal rate.