Paper PS2-TuA3
Validation of Inductively Coupled Plasmas Sustained in Halogen Chemistries

Tuesday, October 20, 2015, 3:00 pm, Room 210B

The growing complexity of industrial plasma processing systems and increasingly stringent technological requirements for plasma processes have necessitated the use of modeling and simulation for design of these systems in recent years. Impressive advances have been made in the development of computer models for plasma equipment design[1,2] and feature profile evolution.[3,4] Validation of these models with experimental data over a wide range of operating conditions is a critical step in making these models a mature development tool. While plasma equipment models have been benchmarked with ion/electron density measurements[5], RF and DC self-bias voltages[6], characterization of neutral species in industrially relevant chemistries is complicated and hence few benchmarking opportunities exist. Characterization of neutral species is critical as they serve as the precursors to any plasma etching (and deposition) process and are an important parameter for plasma equipment models to quantify for use in feature profile models.

In this work, we report on validation of Applied Materials’ fluid plasma model, CRTRS, in an inductively coupled plasma (ICP) reactor sustained in halogen chemistries. Halogen-based ICPs are typically used to etch shallow trench isolation (STI) features and defining gate structures in both logic and memory devices. The density of Cl atoms in Cl₂ chemistries (or Br in HBr chemistries) is an important parameter to characterize the etching process. Recently, researchers have reported on electron and absolute Cl densities and gas temperature in a Cl₂ ICP reactor over a wide range of operating conditions.[7] The fluid plasma model was validated against these experiments for an ICP sustained in Cl₂ and Cl₂/O₂ mixtures over a pressure range of 10 mTorr to 90 mTorr and varying ICP power of 200 W to 500 W. We found gas temperature to be an important parameter to accurately predict the electron and atomic Cl densities as it governs the kinetics of gas phase chemistry and also affects diffusion coefficient.

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[2] M.J. Kushner, J. Phys. D 42, 194013 (2009).

[3] P.J. Stout, S. Rauf, A. Nagy, and P.L.G. Ventzek, J. Vac. Sci. Technol. B 24, 1344 (2006).

[4] S. Rauf, W.J. Dauksher, S.B. Clemens, K.H. Smith, J. Vac. Sci. Technol. A 20, 1177 (2002).

[5] P. Subramonium and M.J. Kushner, Appl. Phys. Lett. 79, 2145 (2001).

[6] A. Agarwal, L. Dorf, S. Rauf, and K. Collins, J. Vac. Sci. Technol. 30, 021303 (2012).

[7] J.P. Booth, Y. Azamoum, N. Sirse, and P. Chabert, J. Phys. D 45, 195201 (2012).