| AVS 64th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Wednesday Sessions |
| Session PS-WeA |
| Session: | Modeling of Plasmas |
| Presenter: | Wei Tian, Applied Materials, Inc. |
| Authors: | W. Tian, Applied Materials, Inc. S. Rauf, Applied Materials, Inc. K.S. Collins, Applied Materials, Inc. |
| Correspondent: | Click to Email |
High selectivity has become a critical requirement for many etching processes during microelectronics fabrication. These processes require good uniformity (both etch rate and critical dimensions) in addition to high selectivity. To meet these challenges, pulsed capacitively coupled plasmas (CCPs) have been introduced due to their ability to better control the flux of ions and radicals to the substrate as well as the energy of the ions incident on the substrate. By pulsing the plasma, one can more effectively modulate the electron energy distribution and the electron impact source functions of reactive species compared to traditional methods.[1,2] Pulsing introduces many additional control variables to already complicated etch processes. In addition, a variety of pulsing schemes are possible in multi-frequency CCPs. To optimize the pulsed CCPs processes, understanding of the transients during a given pulse is the key.
In this work, we will investigate the pulsed Ar/O2/CF4 CCPs using results from a 2-dimensional plasma equipment model.[3] We consider single and dual frequency CCPs, and both single source and synchronous pulsing schemes are investigated. The ignition of the plasma is influenced by the ramp-up of the applied voltage. An overshoot in electron density, electron temperature as well as in emission during the ignition is observed. Depending on the pulse frequency and duty cycle, the plasma during a pulse can be influenced by the previous pulse. The metastable states have a lifetime of milliseconds and are able to accumulate pulse-by-pulse. Through Penning ionization of metastable states, electron and ion densities are affected. The after-glow phase is important for controlling of ion flux and energy, and depends on the voltage decay and sheath collapse. The modeling results are also compared to experimental measurements for validation.[4]
[1] S.-H. Song and M.J. Kushner, Plasma Sources Sci. Technol. 21, 055028 (2012).
[2] A. Agarwal, S. Rauf, and K. Collins, J. Appl. Phys. 112, 033303 (2012).
[3] A. Agarwal, S. Rauf, and K. Collins, Plasma Sources Sci. Technol. 21, 055012 (2012).
[4] Poulose, John. (2016) Temporally, spatially and spectrally resolved studies of pulsed capacitively coupled plasmas (Doctoral dissertation) ProQuest Dissertations Publishing, 10152793.