Patent ID: 6027603
Filing Date: 2000-02-22
Classification: H01J

Abstract:
A vacuum plasma processor for treating a workpiece in a vacuum chamber comprising a vacuum plasma processing chamber arranged to be responsive to a source of ionizable gas and including a holder for the workpiece, a coil reactively coupled with the gas for exciting the gas to a plasma state capable of processing workpieces on the holder, the coil having plural turns and exciting gas to the plasma state in response to r.f. energization of the coil, the coil including interior and exterior segments extending radially and circumferentially with respect to a central region of the coil, the coil including first and second excitation terminals adapted to be connected to a source of the r.f. excitation, the first terminal being at one end of the coil and at one end of the interior segment, the exterior segment being radially displaced from the interior segment, the second terminal being at one of the segments different from the interior segment, the coil, chamber and workpiece being arranged to produce in the chamber a magnetic flux having substantially greater density in peripheral portions of the coil and chamber than in an interior portion of the chamber and coil so a substantially uniform plasma flux is incident on a processed surface of the workpiece, one of the terminals of the coil being connected to the source of the r.f. energization by a reactance, the value of the reactance, the length of the coil and the r.f. energization having a frequency such that peak-to-peak r.f. voltages V.sub.pkpk (x) and currents I.sub.pkpk (x) in the coil are approximated byV.sub.pkpk (x)=V.degree..sub.pkpk cos[.beta.(x+x.degree.)] and I.sub.pkpk (x)=I.degree..sub.pkpk sin[.beta.(x+x.degree.)],where:x is the linear distance measured from an input terminal of the coil connected to the source,.beta. is a constant determined by the frequency of the r.f. energization,x.degree. is an offset from zero determined by the impedance of the reactance at the frequency of the r.f. energization, andV.degree..sub.pkpk and I.degree..sub.pkpk are values of the maximum r.f. peak-to-peak voltages and currents in the coil.