This study presents an optimization framework for designing novel retainer rings (NRR) in chemical mechanical planarization (CMP) to enhance the uniformity of material removal rates (MRR). To improve optimization efficiency, we developed a finite element method (FEM) model alongside a Metamodel of Optimal Prognosis (MOP). The NRR outperformed the reference retainer ring (RRR) in our simulations. We classified simulation cases based on the pressure application area: long (LC), middle (MC), and short (SC). The MOP was constructed using Latin hypercube sampling and refined through an adaptive approach to achieve high accuracy while minimizing computational costs. Optimization was performed using an evolutionary algorithm, generating Pareto fronts for analysis. We evaluated representative designs based on MRR distribution and non-uniformity. Ultimately, Design 2-LC was identified as the optimal choice. The results indicate that the proposed framework effectively enhances MRR uniformity while reducing optimization time.
This study introduces a novel retainer ring design aimed at mitigating the edge effect during chemical mechanical planarization. The innovative design features an arch-shaped geometry that creates a bending effect, thereby reducing excessive pressure on the wafer's edge. A two-dimensional axisymmetric finite element model was developed, and simulation data were utilized to create a metamodel. Multi-objective optimization was conducted using an evolutionary algorithm, focusing on the normal contact stress on the wafer surface. Representative Pareto-optimal designs were analyzed to assess the distribution of normal contact stresses. The results demonstrated that the proposed design significantly reduced peak normal stresses and enhanced stress uniformity, especially at the wafer edge. This optimized retainer ring is anticipated to improve wafer edge quality and increase semiconductor yield.
In this study, to achieve the optimal conditions for mechanical hyper-fine pattern fabrication process, deformation behavior of the materials during indentation scratch test was studied with numerical method by ABAQUS S/W. Brittle materials (Si, Pyrex glass 7740) were used as specimens, and forming conditions to reduce the elastic recovery and pile-up were proposed. The indenter was modeled as a rigid surface. Minimum mesh sizes of specimens are 1-10㎚. Variables of the nanoindentation scratch test analysis are scratching speed, scratching load, tip radius and tip geometry. The nano-indentation scratch tests were performed by using the Berkovich pyramidal diamond indenter. Comparison between the experimental data and numerical result demonstrated that the FEM approach can be a good model of the nanoindentation scratch test. The result of the investigation will be applied to the fabrication of the hyper-fine pattern.
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