Beam-generated plasmas for processing applications

The use of moderate energy electron beams (e-beams) to generate plasma can provide greater control and larger area than existing techniques for proces sing applications. Kilovolt energy electrons have the ability to efficientl y ionize low pressure neutral gas nearly independent of composition. This r esults in a low-temperature, high-density plasma of nearly controllable com position generated in the beam channel. By confining the electron beam magn etically the plasma generation region can be designated independent of surr ounding structures. Particle fluxes to surfaces can then be controlled by t he beam and gas parameters, system geometry, and the externally applied rf bias. The Large Area Plasma Processing System (LAPPS) utilizes a 1-5 kV, 2- 10 mA/cm(2) sheet beam of electrons to generate a 10(11)-10(12) cm(-3) dens ity, 1 eV electron temperature plasma. Plasma sheets of up to 60x60 cm(2) a rea have been generated in a variety of molecular and atomic gases using bo th pulsed and cw e-beam sources. The theoretical basis for the plasma produ ction and decay is presented along with experiments measuring the plasma de nsity, temperature, and potential. Particle fluxes to nearby surfaces are m easured along with the effects of radio frequency biasing. The LAPPS source is found to generate large-area plasmas suitable for materials processing. (C) 2001 American Institute of Physics.