In this article the major kinetics models for plasma-surface interactions were reviewed highlighting their strengths and limitations. As a subset of reactive-site modeling, mixing-layer kinetics model was developed based upon the assumption of random atomic mixing in the top surface layer. The translation of the layer enabled the modeling of both etching and deposition. A statistical concept, nearest-neighbor bonding probability, was defined to express the concentration of any surface moieties with the surface elemental composition. A lumped set of reactions was adopted to carry on the overall physichemical processes including ion incorporation, neutral adsorption, physical sputtering, ion-enhanced etching, dangling bond generation and annihilation, and spontaneous etching. The rate coefficients were fitted to the experimental etching yields at various beam etching conditions. The good match between the kinetics modeling and the experimental results verified the capability of the mixing-layer model of predicting the poly-Si etching in chlorine plasma at various operating conditions. Then the kinetics model was incorporated into the three-dimensional Monte Carlo profile simulator. The concept of the mixing layer was simulated by a cellular-based model through composition averaging among neighboring cells. The reactions were sorted out in terms of ion initiated and neutral initiated, respectively, as discrete events. The reaction rates were calculated based upon the cellular composition and used as probabilities to remove particles from the cell. Results showed that the profile simulation combined with the kinetics, the numeric kinetics model, and the experimental etching yields are in quantitative agreement, which demonstrated the accuracy of kinetics after incorporation into the profile simulation. The simulation was compared to the published research work comprehensively including the etching yields, surface compositions, and dominant product distributions.