| AVS 54th International Symposium | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS2-TuA |
| Session: | Plasma Sources |
| Presenter: | Y. Yang, Iowa State University |
| Authors: | Y. Yang, Iowa State University M.J. Kushner, Iowa State University |
| Correspondent: | Click to Email |
The trend in dielectric etching using capacitively coupled plasmas is use of multiple frequencies where a high frequency (tens to hundreds of MHz) dominates ionization and a low frequency (a few to 10s MHz) is used to control ion energy distributions. As the effective wavelength in the plasma waveguide represented by the reactor decreases with increasing frequency, electromagnetic wave propagation effects become a concern and may give rise to limitations on processing uniformity. These effects have been investigated experimentally but are difficult to address computationally in arbitrary geometries due to the coupling between the electromagnetic and the electrostatic fields, the latter of which is responsible for the formation of the sheath. In this talk, we discuss results from a computational investigation of high frequency effects in capacitively coupled plasmas. A full Maxwell solver based on the concept of vector and scalar potentials, and capable of resolving wave effects in a self-consistent manner in arbitrary geometries, was developed and incorporated into the Hybrid Plasma Equipment Model, a two-dimensional hybrid simulation. In particular, the capability to address multiple frequencies in the time domain are included. To properly capture high frequency heating, excitation rates are provided by spatially dependent electron energy distributions generated by a Monte Carlo simulation. The method of solution will be discussed and comparisons made to using a conventional electrostatic method for electric fields. Results from investigations of dual frequency CCPs (low frequency < 10 MHz, high frequency > 50 MHz) in 10s of mTorr polymerizing and non-polymerizing gas mixtures will be discussed. Assessments of the change in power deposition profile as a function of frequency will be made.
*Work supported by the Semiconductor Research Corp. and the National Science Foundation.