Low-frequency, high-density, inductively coupled plasma sources: Operationand applications

Operation regimes, plasma parameters, and applications of the low-frequency (similar to 500 kHz) inductively coupled plasma (ICP) sources with a plana r external coil are investigated. It is shown that highly uniform, high-den sity (n(e)similar to 9x10(12) cm(-3)) plasmas can be produced in low-pressu re argon discharges with moderate rf powers. The low-frequency ICP sources operate in either electrostatic (E) or electromagnetic (H) regimes in a wid e pressure range without any Faraday shield or an external multipolar magne tic confinement, and exhibit high power transfer efficiency, and low circui t loss. In the H mode, the ICP features high level of uniformity over large processing areas and volumes, low electron temperatures, and plasma potent ials. The low-density, highly uniform over the cross-section, plasmas with high electron temperatures and plasma and sheath potentials are characteris tic to the electrostatic regime. Both operation regimes offer great potenti al for various plasma processing applications. As examples, the efficiency of the low-frequency ICP for steel nitriding and plasma-enhanced chemical v apor deposition of hydrogenated diamond-like carbon (DLC) films, is demonst rated. It appears possible to achieve very high nitriding rates and dramati cally increase micro-hardness and wear resistance of the AISI 304 stainless steel. It is also shown that the deposition rates and mechanical propertie s of the DLC films can be efficiently controlled by selecting the discharge operating regime. (C) 2001 American Institute of Physics.