US Patent 7312162 Low temperature plasma deposition process for carbon layer deposition

A method of depositing a carbon layer on a workpiece includes placing the workpiece in a reactor chamber, introducing a carbon-containing process gas into the chamber, generating a reentrant toroidal RF plasma current in a reentrant path that includes a process zone overlying the workpiece by coupling plasma RF source power to an external portion of the reentrant path, and coupling RF plasma bias power or bias voltage to the workpiece.