Improvement of ICP plasma with periodic control of axial magnetic field

Various types of plasma sources, such as ECR, planar ICP (or TCP), helical ICP, Helicon, Helical Resonator, or SWP, have been researched to improve th e plasma density or to remove or decrease the micro-loading effect effectiv ely. Among them, ICP type plasma source, well known to provide uniform high density plasma, has been improved to provide better quality. Here, we prop ose a novel technique, named 'enhanced ICP', to accommodate better process quality, and we report improved results, a uniform and stable plasma with l ow electron temperature and high ion density. A photo-resist etch uniformit y of below 1% within 10 cm in diameter has been accomplished with improved plasma density and the low electron temperature of 1 eV. It was obtained by applying an axial magnetic field with periodic on/off control of current i n the Helmholtz coil surrounding the normal ICP plasma chamber. The frequen cy control of the coil current, which might vary as the chamber geometry or the operating condition changes, is considered to resonate the transition between the novel wave modes of plasma to enhance the process uniformity. ( C) 1999 Elsevier Science S.A. All rights reserved.