(460d) Predicting the Surface Response Upon Simultaneous Plasma Etching and Deposition

As the downscaling of integrated circuit devices continues, the effect of variations in feature profile evolution from processing techniques such as plasma etching becomes greatly magnified. In order to accurately simulate such processes, modeling across a variety of length and time scales is required, from the bulk discharge in the reactor to the material surface layers. The complexity of this task is compounded by the fact that etching and deposition reactions often take place concurrently, which must be taken into account even if the net effect of the process is known. We adapt a previously developed phenomenological model¹ for use in conjunction with reactor scale and Monte Carlo based simulation tools, with the ultimate goal of predicting feature profile evolution. Experimental measurements or reactor-scale simulations are used to obtain species fluxes,² and agreement with reported results in literature are examined. The aforementioned surface site-based phenomenological model has demonstrated predictive capabilities for both etching and deposition processes, but can not be readily integrated with the cell based Monte Carlo method. Therefore, a translated mixed layer kinetics (TML) model³ is utilized to model the detailed surface reactions such as ion impingement, neutral adsorption, physical sputtering and chemically enhanced ion etching. Reaction parameters that cannot be measured directly can be extracted or fitted by comparing the model to etch yield data. The results are then compared to the phenomenological model as a test of accuracy. The surface composition taken via x-ray photoelectron spectroscopy is also used as verification before incorporating the results from this model into a feature scale 3D Monte Carlo simulator. 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. Obtained profiles are then compared to cross-sectional SEM images of the material systems and display reasonable agreement. This approach thus spans the three major regimes and we applied it to successfully to systems dominated by etching (shallow trench isolation of Si in Cl₂/O₂ plasmas), deposition (Cu IPVD), and simultaneous etching and deposition (high-k films (HfO₂, Al₂O₃, HfAlO) in Cl₂/BCl₃ plasmas).

¹Martin et al. Journal of Vacuum Science and Technology A 27(2) 2009

²Hsu et al. Journal of Vacuum Science and Technology B. 26 (6) 2008

³Kwon et al. Journal of Vacuum Science and Technology A. 24(5) 2006