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Analysis of First Wafer Effect for Si Etch Rate with Plasma Information Based Virtual Metrology  

Ryu, Sangwon (Department of Energy Systems Engineering, Seoul National University)
Kwon, Ji-Won (Department of Energy Systems Engineering, Seoul National University)
Publication Information
Journal of the Semiconductor & Display Technology / v.20, no.4, 2021 , pp. 146-150 More about this Journal
Abstract
Plasma information based virtual metrology (PI-VM) that predicts wafer-to-wafer etch rate variation after wet cleaning of plasma facing parts was developed. As input parameters, plasma information (PI) variables such as electron temperature, fluorine density and hydrogen density were extracted from optical emission spectroscopy (OES) data for etch plasma. The PI-VM model was trained by stepwise variable selection method and multi-linear regression method. The expected etch rate by PI-VM showed high correlation coefficient with measured etch rate from SEM image analysis. The PI-VM model revealed that the root cause of etch rate variation after the wet cleaning was desorption of hydrogen from the cleaned parts as hydrogen combined with fluorine and decreased etchant density and etch rate.
Keywords
Virtual Metrology; Plasma Information; First Wafer Effect; Optical Emission Spectroscopy; Plasma Etch;
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