Electron-Beam Controlled Radio Frequency Discharges for Plasma Processing

J. Vac. Sci. Technol., 14(4), 2094-2101 (1996).

Kushner, M. J., Collison W. Z., Ruzic, D. N.

During plasma etching and deposition of semiconductor materials, it is desirable to have separate control over the magnitude and energy of the ion flux onto the substrate. This control is difficult to achieve in reactive ion etching discharges since the radio frequency (rf) voltage applied to the substrate both generates the ions and accelerates the ions into the substrate. High plasma density devices such as electron cyclotron resonance and inductively coupled plasma reactors achieve this control by having separate power sources for ionization and ion acceleration. In this article, we present results from a computational study of an electron beam controlled rf discharge in which the production and acceleration of ions are similarly separately controlled. Ionization is dominantly produced by injection of an electron beam into the reactor. Ion acceleration is determined by a separate rf bias applied to the substrate. The limits of e-beam voltage, current, and rf bias voltage for which this separate control can be achieved will be discussed.