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25 August 1997 Model-based control of chemical mechanical polishing
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Chemical mechanical polishing (CMP) of silicon oxide interlayer dielectric is a critical process in modern multi- layer metal integrated circuit manufacturing. In this process, the rate of planarization of features on a silicon wafer surface changes with age of the polishing pad. This effect creates the need for adjustment of polishing times to compensate for changes in planarization rates. The way that planarization rate varies with polish time must be defined to develop robust control of this process. In this work, a theoretical model for the dependence of planarization rate on polish time was developed. This model was then applied to data from a Westech 472 CMP system and shown to accurately capture the time variation of measured removal rates. A control algorithm using this model was tried using a different CMP tool, the Westech 372, creating a mismatch between the control model and process. Nonetheless, the control model quickly adapted to the new conditions and controlled the process well.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Anthony J. Toprac "Model-based control of chemical mechanical polishing", Proc. SPIE 3213, Process, Equipment, and Materials Control in Integrated Circuit Manufacturing III, (25 August 1997);

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