Electron Collision Physics

Kinema Research provides consulting and performs research in the area of electron collision physics.

We are specialists in performing electron transport swarm analyses in estimating cross sections and in assembling and validating self-consistent sets of electron cross sections used in plasma modeling. The methods involve the use of optimization algorithms, our ELENDIF code for solving Boltzmann’s equation, and Monte Carlo simulations under some circumstances [See References (1)-(4)]. Molecules for which we have recently assembled self-consistent cross sections include C2F4 [4], CHF3 [5], c-C4F8 [6], and TEOS [7].

References [8] and [9] are critical reviews of cross sections for Cl2, F2, HCl, CF4, SiH4, and CH4 in which we used this methodology.

The following abstract illustrates current research in this area.

AN ASSESSMENT OF ELECTRON COLLISION CROSS SECTIONS FOR C2F4

W. L. MORGAN Kinema Research, Monument, Colorado and S. J. BUCKMAN, Australian National University, Canberra, Australia

Electron collisions with C2F4 are of interest to the plasma processing community it is used both as a feed gas in its own right and is an important dissociative by-product of processing plasmas which use c-C4F8 as a feed gas. Until recently there have been very few absolute scattering measurements for low energy electron collisions with C2F4 and a recently published cross section set [1] was based on a combination of theoretical estimates and analysis of electron transport parameters. In the light of recent, absolute measurements [2] for elastic scattering and vibrational excitation, this cross section set has been re-assessed and some significant differences are apparent.

[1] K. Yoshida et al. J. Appl. Phys. 91, 2637 (2002)

[2] R. Kajita et al. To be published.


References

1. “Electron Collision Data for Plasma Chemistry Modeling”, W. L. Morgan, Advances in Atomic, Molecular, and Optical Physics 43 (2000).

2. “ELENDIF: A Time Dependent Boltzmann Solver for Partially Ionized Plasmas”, W. L. Morgan and B. Penetrante, Comp. Phys. Comm. 58, 127 (1990).

3. “Test of a Numerical Optimization Algorithm for Obtaining Cross Sections for Multiple Collision Processes from Electron Swarm Data”, W. L. Morgan, J. Phys. D 26, 209 (1993).

4. “Electron Transport Properties and Collision Cross Sections in C2F4”, K. Yoshida, S. Goto, H. Tagashira, C. Winstead, B. V. McKoy, and W. L. Morgan, J. Appl. Phys. 91, 2637 (2002).

5. “Electron Cross Section Set for CHF3”, W. L. Morgan, C. Winstead, and V. McKoy, J. Appl. Phys. 90, 2009 (2001).

6. “Cross Section Set and Chemistry Model for the Simulation of c-C4F8 Plasma Discharges”, G. I. Font, W. L. Morgan, and G. Mennenga, J. Appl. Phys. 91, 3530 (2002).

7. “Electron Collision Cross Sections in Tetra ethoxysilane (TEOS)”, W. L. Morgan, C. Winstead, and V. McKoy, J. Appl. Phys. 92, 1663 (2002).

8. “A Critical Evaluation of Low-Energy Electron Impact Cross Sections for Plasma Processing Modeling I: Cl2, F2, and HCl”, W. L. Morgan, Plasma Chemistry and Plasma Processing 12, 449 (1992).

9. “A Critical Evaluation of Low-Energy Electron Impact Cross Sections for Plasma Processing Modeling II: CF4, SiH4, and CH4”, W. L. Morgan, Plasma Chemistry and Plasma Processing 12, 477 (1992).