Paper PS1-ThA7
Predicting the Surface Response Upon Simultaneous Plasma Etching and Deposition

Thursday, October 21, 2010, 4:00 pm, Room Aztec

As the downscaling of integrated circuit devices continues, minute variations in the feature profiles from processing techniques such as plasma etching significantly affect device performance . Thus, there is a need to predict the surface response during etching of a variety of materials, such as complex oxides. To accurately represent the kinetics involved, experiments are conducted in this work in an inductively coupled plasma (ICP) reactor equipped with a quadrupole mass spectrometer (QMS) for analyzing etch products and a quartz crystal microbalance (QCM) for measuring the etch rate in situ. This reactor is connected to a UHV transfer tube which allows the surface composition to be studied via x-ray photoelectron spectroscopy (XPS) without exposure to ambient conditions. The materials system studied include Hf-based high-k materials and YMnO₃, a multiferroic oxide, etched in Cl₂/BCl₃ plasmas. A surface site-based phenomenological model¹ that was previously developed for binary and ternary oxides is shown to be applicable to the prediction of how these complex oxides were etched. To use this model in a cell based Monte Carlo simulator to predict feature profile evolution, a translated mixed layer (TML) kinetics model² is utilized to describe the surface reactions such as ion impingement, neutral adsorption, physical sputtering and chemically enhanced ion etching. Reaction parameters that cannot be measured directly are extracted by comparing the model to etch yield data and validated against the phenomenological model. Ion incident angle dependence and an elliptical energy deposition model were used to capture the effects of surface morphology on the profile evolution under the bombardment of energetic and directional ions. Simulated profiles are compared to cross-sectional SEM images of the patterned material systems and display reasonable agreement.