| AVS 61st International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS2-WeM |
| Session: | Plasma Modeling |
| Presenter: | Shahid Rauf, Applied Materials Inc. |
| Authors: | S. Rauf, Applied Materials Inc. A. Balakrishna, Applied Materials Inc. A. Agarwal, Applied Materials Inc. J. Kenney, Applied Materials Inc. L. Dorf, Applied Materials Inc. K. Collins, Applied Materials Inc. |
| Correspondent: | Click to Email |
Plasmas generated using energetic electron beams have unique properties that make them attractive for emerging plasma processing applications. In the pioneering work done at the Naval Research Laboratory, [1] it has been demonstrated that electron temperature (Te) in the electron-beam generated plasmas is typically < 0.8 eV while electron densities are comparable to those obtained in radio-frequency (RF) inductively and capacitively coupled plasmas. In addition, the ions and radicals are primarily produced by highly energetic electrons (few keV) instead of electrons in the tail of a low energy distribution. The plasma chemistry in electron-beam generated plasmas is therefore significantly different to RF plasmas with a much higher ion to neutral radical density ratio. As feature dimensions shrink below 20 nm in microelectronics devices with atomic level precision required during manufacturing, the unique properties of electron-beam generated plasmas (low Te, low ion energy and unique chemistry) are increasingly becoming attractive for plasma processing in the semiconductor industry.
For typical gas pressures used in electron beam generated plasmas ( – 50 mTorr), self-induced electric field and collisions can quickly broaden the electron beam. A relatively strong magnetic field parallel to the beam direction has therefore been employed to confine the electron beam. [1] Many complex mechanisms effect uniformity of a magnetized plasma, especially if the magnetic field is inhomogeneous and near the edges of the plasma. We have developed a 3-dimensional plasma model to better understand the spatial characteristics of electron-beam generated magnetized plasmas. The bulk plasma electrons are treated as a fluid and the model includes continuity equations for charged and neutral species, momentum equation for ions, and energy conservation equation for electrons. A Monte Carlo model is used for electron beam transport through the vacuum and plasma regions, which includes gas phase collisions and the effect of magnetic field and electric fields on electron motion.
The 3-dimensional plasma model is used to understand the spatial characteristics of electron beam generated Ar, N2 and O2 plasmas. These simulations have been done for a plasma chamber with radius < 30 cm, and several magnet designs. The impact of magnetic field, beam electron energy, and gas pressure on uniformity of important plasma properties (electron and ion densities, radical densities, Te) is examined. Modeling results are also validated against probe measurements. [1]
[1] E. H. Lock et al., Plasma Sources Sci. Technol. 17, 025009 (2008).