Hydrodynamic Analysis And Simulation Of Circular Translational Polishing

Chemical-mechanical-polishing (CMP) has been rapidly developing and finding extensive applications in the integrated circuit (IC) manufacturing industry for processing hard disk of computer and silicon wafer with super-smooth and flawless surface. Because there are some limitations in traditional CMP method, it is necessary to develop new techniques with high work efficiency and polishing quality to meet further growing demand of IC manufacture industry pushed forward by rapid development of micro-electronics, computer, communications and internet technology.Circularly translational-moving polishing (CTP) is a new type polishing method with best kinematics conditions of polishing, and can obtain better work efficiency and quality than the traditional CMP method. During the CTP process, the wafer or polishing pad is fixed and another component is translationally moving along a circular track with constant velocity.In order to evaluate the capability of CTP in theory and understand the mechanisms of CTP, the hydrodynamic model of CTP without considering deformation of pad was set up and solved by numerical method. The model involves two contact conditions: the full-film contact and partial-film contact. Base on the kinematics relation of CTP, the corresponding Reynolds equation or average Reynolds equation, fluid film thickness equation under qusi-stable state in polar coordinates, balance equations of load and moments under full-film contact and partial-film contact states were set up respectively. These model equations were calculated by the finite difference method, and the instantaneous 3-D distribution of fluid pressure and the slurry film was simulated by the Matlab software. The effects of pitch angle, rolling angle, pad velocity, rotation speed and standard nominal clearance on load and moments were obtained by analyzing the numerical results, and the effects of external load, external moments (x-axis and y-axis), rotation speed and pad velocity on fluid pressure distribution, on tilt angles, azimuth angle and standard nominal clearance are further studied. The reason for the existence of negative pressure in CTP and its effect on the polishing result was discussed. It is proved that CTP can achieve the best...