Wave propagation and power deposition in magnetically enhanced inductivelycoupled and helicon plasma sources

Magnetically enhanced inductively coupled plasma (MEICP) and helicon source s for materials processing are of interest because of their ability to depo sit power within the volume of the plasma beyond the classical skin depth. The location and manner of power deposition can vary substantially dependin g on the mode of operation and reactor conditions. The coupling of electrom agnetic fields to the plasma typically occurs through two channels; a weakl y damped heliconlike wave that penetrates into the bulk plasma and an elect rostatic wave. The electrostatic wave can often be suppressed resulting in the helicon component being responsible for the majority of the power depos ition. A computational investigation was conducted to quantify this heating and determine the conditions for which power can be deposited in the downs tream region of MEICP devices. For typical process conditions (10 mTorr, 1 kW ICP) and magnetic fields above 40 G, radial and axial electric fields ex hibit nodal structure consistent with helicon behavior. As the magnetic fie lds are increased, axial standing wave patterns occur with substantial powe r deposition downstream. The ability to deposit power downstream with incre asing B field is ultimately limited by the increasing wavelength. For examp le, if the plasma is significantly electronegative in the low power-high ma gnetic field regime, power deposition resembles conventional ICP due to the helicon wavelength exceeding the reactor. (C) 2001 American Vacuum Society . [DOI: 10.1116/1.1329122].