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Author: Sutee Eamkajornsiri Publisher: ISBN: Category : Languages : en Pages : 210
Book Description
Chemical mechanical polishing (CMP) is a planarization process that produces high quality surfaces both locally and globally. It is one of the key process steps during the fabrication of very large scale integrated (VLSI) chips in integrated circuit (IC) manufacturing. CMP consists of a chemical process and a mechanical process being performed together to reduce height variation across a wafer. High and reliable wafer yield, which is dependent upon uniformity of the material removal rate across the entire wafer, is of critical importance in the CMP process. In this thesis, the wafer pad contact is modeled as the indentation of a rigid indenter on an elastic half-space. The model predictions are first verified against experimental observations. Simulation results for wafer yield under open loop processing conditions are presented. Wafer curvature is identified as a key design variable influencing the spatial distribution of the material removal rate. The load control, the curvature control, the combined curvature and load strategies are investigated for improving the wafer yield. It utilizes an objective function based on minimizing a moment function that represents the wafer curvature and the height of the oxide layer left for material removal. Simulation results indicate that curvature control can improve wafer yield significantly, and is more effective that just the load control.
Author: Sutee Eamkajornsiri Publisher: ISBN: Category : Languages : en Pages : 210
Book Description
Chemical mechanical polishing (CMP) is a planarization process that produces high quality surfaces both locally and globally. It is one of the key process steps during the fabrication of very large scale integrated (VLSI) chips in integrated circuit (IC) manufacturing. CMP consists of a chemical process and a mechanical process being performed together to reduce height variation across a wafer. High and reliable wafer yield, which is dependent upon uniformity of the material removal rate across the entire wafer, is of critical importance in the CMP process. In this thesis, the wafer pad contact is modeled as the indentation of a rigid indenter on an elastic half-space. The model predictions are first verified against experimental observations. Simulation results for wafer yield under open loop processing conditions are presented. Wafer curvature is identified as a key design variable influencing the spatial distribution of the material removal rate. The load control, the curvature control, the combined curvature and load strategies are investigated for improving the wafer yield. It utilizes an objective function based on minimizing a moment function that represents the wafer curvature and the height of the oxide layer left for material removal. Simulation results indicate that curvature control can improve wafer yield significantly, and is more effective that just the load control.
Author: Sutee Eamkajornsiri Publisher: ISBN: Category : Languages : en Pages : 298
Book Description
Chemical mechanical polishing (CMP) is a planarization process that produces high quality surfaces both locally and globally. It is one of the key process steps during fabrication of very large scale integrated (VLSI) chips in integrated circuit (IC) manufacturing. High and reliable wafer yield is critical in the CMP process; it is dependent upon uniformity of material removal rate across the entire wafer. The focus on this research is the development of control algorithm for CMP process. Wafer-scale and die-scale models are the two scales used in this study. To achieve improvement in wafer yield, three control strategies are formulated with greedy algorithm, method heuristic and non-linear programming in this wafer-scale. The simulation results show that average wafer yield from genetic algorithm is improved, compared to greedy algorithm. Moreover, average wafer yield from non-linear programming is also improved, compared to greedy algorithm. At die-scale, a comprehensive control algorithm is developed based on the MRR equations with interface pressure as a control parameter. The interface pressure is varied spatially and/or temporally across the die. In this concept, three control strategies are developed and studied. The strategies are included spatial pressure control, spatial and temporal pressure control, and look-ahead scheduled pressure control. The simulation results of these three strategies show improvement in the upper surface uniformity; however, look-ahead scheduled pressure control seems to be the promising algorithm.
Author: Materials Research Society. Meeting Publisher: ISBN: Category : Science Languages : en Pages : 318
Book Description
The MRS Symposium Proceeding series is an internationally recognised reference suitable for researchers and practitioners. This book, first published in 2004, presents advances in fundamental understanding, development, and applications of chemical-mechanical polishing (CMP).
Author: Guanghui Fu Publisher: ISBN: Category : Languages : en Pages : 258
Book Description
Chemical Mechanical Polishing (CMP) has grown rapidly during the past decade as part of mainstream processing method in submicron integrated circuit manufacturing because of its global or near-global planarization ability. However, CMP process is influenced by many factors and is poorly understood. It makes process control and optimization very difficult. This study focuses on the modeling and simulation to facilitate better understanding and better control of the CMP process. The thesis outlines the modeling of CMP process in three scales: particle scale for material removal mechanism, wafer scale for within wafer nonuniformity issues and feature scale for dishing and erosion in metal CMP. At the particle scale, material removal mechanism is assumed to be due to local plastic deformation of wafer surface material. A mechanistic material removal model is derived that delineates the influence of abrasive (shape, size and concentration), pad (rigidity) and process parameters (pressure and relative velocity) on the material removal rate (MRR). Wafer scale model is based on the solution of indentation of elastic half space by a rigid frictionless polynomial punch. The load-displacement relationship is also derived and the conditions for unbonded or bonded contact are obtained from the boundary condition at punch edge. The corresponding viscoelastic solution is obtained through Laplace transform and elastic-viscoelastic analogy. The elastic solution is used to explain the edge effect. Viscoelastic solution is used to explain MRR decay for unconditioned pad. The relationships among wafer-pad interface pressure, wafer shape and wafer loading condition are also investigated. Feature scale model is based on Preston's relationship for material removal and constant downforce. It shows dishing is governed by polishing conditions (overpolishing, pressure, velocity), slurry (selectivity), pad characteristics (pad stiffness and bending ability), as well as wafer surface feature topography (pattern density, linewidth and pitch). This model is also valid for step height reduction when the same surface material is polished. Due to process complexity and coupling of various parameters, more fundamental research needs to be carried out and carefully designed experiments need to be done to verify the models. Recommendations for future research work is presented at the end.
Author: Sutee Eamkajornsiri
Author: Sutee Eamkajornsiri
Author: Sutee Eamkajornsiri
Author: Materials Research Society. Meeting
Author: Guanghui Fu
Author: S. V. Babu
Author: 
Author: 
Author: Iqbal Ali
Author: 
Author: Andrew Kunung Chang