Electron Transport in Nonorthogonal Crossed DC Electric and Magnetic Fields

Abstract

Transport and plasma chemistry in magnetized plasma sources for plasma processing are become increasingly important. Beyond the plasma shaping and confinement associated with magnetic fields in magnetically enhanced reactive ion etching (MERIE) tools, magnetized inductively coupled plasmas and conventional magnetrons, there are electron-kinetics-driven chemistry functions as well. It is difficult to capture these effects using conventional fluid or hybrid approaches, as it is not straightforward how to map transport and kinetic macroparameters onto common orthogonal grids. This paper addresses this issue by characterizing macroparameters (also known as swarm parameters) as a function of crossed electric and magnetic field crossing angle for Cl2 and SiH4. Scaling or mapping criteria (i.e., mapping of swarm parameters onto an orthogonal numerical grid) are described to be a function of the relative position of the energy threshold of collision processes and the mean electron energy. Using these criteria, the transport or kinetic parameters may be mapped either by angle cosines or by their components on an orthogonal grid. Significant exceptions to this occur for certain inelastic processes. When threshold energies coincide with the mean electron energy, it is not possible to determine simple mapping criteria independent of exact knowledge of how the parameters behave at a specific crossing angle.