A multitude of models exist to predict the material removal rate (MRR) during CMP. Common among many of these models is the prediction of the MRR based on the product of the material removal rate per particle (MRR PP ) and the number of active particles, N act , actively contributing to the material removal. Discrepancies between CMP models and experiments are sometimes compensated for by empirical wear coefficients that are used as fitting parameters placed on the overall CMP model. However, such empirical correlations can obscure deficiencies in the prediction of the material removed per particle and the number of active particles. A decoupled understanding of both MRR PP and N act is essential for accurate modeling of CMP. This work investigates the predictions of several active particle models, decoupled from the prediction of the MRR, to assess their agreement. In addition to the number of active particles, the models are used to predict the number of particles in the interface and the number of particles eligible to become active. It is found that although the models differ greatly in their assumptions to predict these quantities, there is some similarity in their prediction of the number of active particles.Integrated circuits (ICs) are used in almost every modern electronic device. Typically, IC's are built on silicon wafers in a process that involves many deposition and material removal steps. Chemical mechanical polishing (CMP) is a commonly used planarization technique for the IC manufacturing industry. 1 It is a critical process in which material is removed from the wafer before the next layer of the IC is constructed. CMP is employed because of its ability to produce flat surfaces with low levels of roughness. Both of these qualities are desired during IC fabrication because variation in the surface of one layer can propagate to other layers, as the IC is fabricated. Moreover, the critical downstream step of lithographic patterning can be unsuccessful if the wafer surface is not planarized. During CMP, the wafer is rotated and pressed into a rotating polishing pad. A chemically-active slurry, containing abrasive nanoparticles, is entrained between the rotating polishing pad and the wafer. The nanoparticles in the slurry wear the surface of the wafer until the unwanted material is removed. Differential wear rates on the wafer during CMP have been shown to produce defects in the IC. 2 These defects negatively affect the IC performance and can lead to reduced production yields. As a result, there have been many models developed which have helped to elucidate the complex behavior during CMP in the past few years. 3-6 In 2009, Oh and Seok 7 proposed that non-Prestonian behavior during CMP could be modeled using a modified version of Zhao and Chang's prediction for active particles 3 and a diffusion model to capture the effect of the slurry chemicals on the wafer. 7 Oh and Seok introduced two fitting parameters, related to the pad-wafer contact, to align the number of abrasive particles removing material p...