PLASMA PROPERTIES DETERMINED WITH INDUCTION LOOP PROBES IN A PLANAR INDUCTIVELY-COUPLED PLASMA SOURCE

Electromagnetic fields in a planar rf inductively coupled plasma sourc e, of interest for materials processing, were measured using a two-loo p inductive (B-dot) probe. The two loops were oriented to measure the time derivative of the axial and radial components of the magnetic fie ld Boverdot(z) and Boverdot(r), respectively, at various positions in the r-z plane of the cylindrically symmetric argon discharge. Maxwell' s equations were used with this data to calculate amplitudes of the rf azimuthal electric field E(phi) and current density J(phi), as well a s the complex permittivity E of the plasma, from which the electron de nsity n(e) was calculated. The electron densities calculated using thi s technique were found to compare favorably to the results of measurem ents made with Langmuir probes. Electron drift velocities calculated f rom J(phi) and n(e) were found to be comparable to electron thermal ve locities in the region of highest E(phi) and thus may contribute to lo cal enhancement of electron impact reactions, thereby affecting proces s chemistry and uniformity. The peak in the drift velocity moved radia lly outward as the pressure increased due changes in the radial plasma density profile. This technique is applicable to chemistries where La ngmuir probes are not practical. (C) 1996 American Institute of Physic s.