AVS 59th Annual International Symposium and Exhibition
    Plasma Science and Technology Monday Sessions
       Session PS2-MoA

Paper PS2-MoA3
Self-Consistent Multi-Dimensional Modeling of Inductively Coupled Plasmas

Monday, October 29, 2012, 2:40 pm, Room 25

Session: Plasma Modeling
Presenter: A. Agarwal, Applied Materials Inc.
Authors: A. Agarwal, Applied Materials Inc.
J. Kenney, Applied Materials Inc.
M.-F. Wu, Applied Materials Inc.
S. Rauf, Applied Materials Inc.
K. Collins, Applied Materials Inc.
Correspondent: Click to Email
Plasma etching of microelectronic structures at advanced technological nodes (< 2x nm), especially complicated structures such as multi-gate MOSFETs and 3D memory stacks, places great emphasis on uniformity of the process.[1] Asymmetries, either azimuthal or radial, can arise in inductively coupled plasma (ICP) sources due to the input and pumping locations of feedstock gases, voltage and current variations along the coils, and other particulars of the reactor configuration.[2] While two-dimensional plasma models are adequate to tackle radial non-uniformities during design of ICP systems, these models usually do not address the circuit issues and are incapable of investigating azimuthal asymmetries.

In this work, results from a two-dimensional plasma model, HPEM[3], modified to include match-side circuit calculations, will first be discussed to highlight the effect of coil voltages on capacitive coupling in ICPs. The model is validated using voltage and current measurements in the match and along the coils. The consequences of capacitive coupling on the plasma and ion energy distribution characteristics will be discussed.

With increasing coil dimensions, voltage and current can vary along the coils which can produce azimuthal asymmetries. Mitigation of these non-uniformities requires a careful antenna design. However, as these azimuthal non-uniformities cannot be predicted by a two-dimensional model, a three-dimensional model is required to help with antenna design for ICPs. We discuss results from three-dimensional modeling of ICPs using the plasma-electromagnetics modeling code, Mira.[4] Mira is a fully electromagnetic fluid plasma model which self-consistently computes the electromagnetic fields using the finite-difference time domain (FDTD) technique. By virtue of the fully electromagnetic nature of the model, both capacitive and inductive fields are self-consistently included while computing the power deposition in the plasma. The effect of various azimuthally asymmetric reactor configurations and coil designs on plasma uniformity will be discussed.

[1] K. Ahmed and K. Scheugraf, IEEE Spectrum 48 (11), 50 (2011).

[2] J.A. Kenney, S. Rauf, and K. Collins, J. Appl. Phys. 106, 103302 (2009).

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

[4] S. Rauf, Z. Chen, and K. Collins, J. Appl. Phys. 107, 093302 (2010).