Characterization of an azimuthally symmetric helicon wave high density plasma source

A cylindrically symmetric (azimuthal mode number m=0) resonant inductive (MORI(TM)) radio frequency (rf) helicon wave high density plasma source is described. The source consists of an antenna and bell jar generator immersed in a diverging magnetic field. Plasma is generated in this upstream region and then is transported along the field lines into the low-field downstream processing chamber. A propagating wave is observed in the plasma with rf spatial distribution and propagation characteristics that obey the theoretical m=0 helicon wave dispersion relation. By varying the divergence of the source magnetic field, the wafer etch rate and etch uniformity can be controlled. Spatially resolved optical emission spectroscopy shows that molecular gases are almost completely dissociated near the plasma center and have a uniform radial distribution. Highly uniform plasma and neutral distributions are then produced at the wafer location, and have been used in a variety of etch applications. (C) 1997 American Vacuum Society. [S073-2101(97)04206-1].