ELECTRON-BEAM CONTROLLED RADIO-FREQUENCY DISCHARGES FOR PLASMA PROCESSING

During plasma etching and deposition of semiconductor materials, it is desirable to have separate control over the magnitude and energy of t he ion flux onto the substrate. This control is difficult to achieve i n reactive ion etching discharges since the radio frequency (rf) volta ge applied to the substrate both generates the ions and accelerates th e ions into the substrate. High plasma density devices such as electro n cyclotron resonance and inductively coupled plasma reactors achieve this control by having separate power sources for ionization and ion a cceleration. In this article, we present results from a computational study of an electron beam controlled rf discharge in which the product ion and acceleration of ions are similarly separately controlled. Ioni zation is dominantly produced by injection of an electron beam into th e reactor. Ion acceleration is determined by a separate rf bias applie d to the substrate. The limits of e-beam voltage, current, and rf bias voltage for which this separate control can be achieved will be discu ssed. (C) 1996 American Vacuum Society.