Integrated modeling of chemical mechanical planarization/polishing (CMP) for integrated circuit fabrication: From particle scale to die and wafer scales

Chemical mechanical planarization/polishing (CMP) has obtained broad applications in sub-micron integrated circuit (IC) fabrication in recent years. These applications include inter-layer dielectrics planarization, copper damascene process and shallow trench isolation. However, the broad applications of CMP are often limited by a general lack of understanding of the process. With the technology nodes going to 65nm, a more predictable, controllable and reproducible CMP process is needed. Modeling and simulation of CMP will be critical to satisfy the requirements.; This work aims to model the CMP process at three scales, namely, particle scale, die scale and wafer scale. The particle-scale model is to understand the roles and interactions of consumable parameters in CMP. The topography and material properties of the pad, abrasive particle size and size distribution, abrasive weight concentration and slurry chemicals influencing the passivation rate of wafer surface are identified as the most important parameters in the CMP material removal process. Based on the model, they contribute to the material removal through two parameters; one, the number of active abrasives over the wafer-pad interface, and the other, material removal by a single active abrasive.; The number of active abrasives first depends on the pad topography and abrasive weight concentration. A rough pad can capture more abrasives. A larger abrasive weight concentration indicates a larger number of abrasives per unit volume of slurry. Further, the abrasive size distribution is critical for the number. Only a small portion of abrasives on the tail of the distribution function are involved in the material removal process. This portion is a function of the gap between wafer and pad over the contact area with abrasives in-between. Only abrasives larger than the gap, which is determined by the wafer-pad contact ratio (function of pad topography and pad Young's modulus) and pad hardness, can be involved in the material removal process.; The material removed by a single active abrasive is determined by the size of abrasive and force applied on the abrasives. The force is a function of wafer-pad contact area ratio. The average size of active abrasives depends on the abrasive size distribution. The roles of abrasive size distribution in material removal are therefore two fold. While the portion is increased with the gap, the size of active abrasives becomes smaller. (Abstract shortened by UMI.)...