Inductively coupled source for deriving substantially uniform plasma flux
First Claim
1. 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 arcuate segments and 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 arcuate segment, the exterior arcuate segment being radially displaced from the interior arcuate segment, the second terminal being at one of the arcuate segments different from the interior arcuate 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 a center 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 Vpkpk (x) and currents Ipkpk (x) in the coil are approximated by
where;
(x+x.sup.o)! and I.sub.pkpk (x)=I.sup.o.sub.pkpk sin β
(x+x.sup.o !,
x is the linear distance measured from an input terminal of the coil connected to the source,β
is a constant determined by the frequency of the r.f. energization,xo is an offset from zero determined by the impedance of the reactance at the frequency of the r.f. energization, andVopkpk and Iopkpk are values of the maximum r.f. peak-to-peak voltages and currents in the coil.
1 Assignment
0 Petitions
Accused Products
Abstract
A planar coil exciting a plasma of an r.f. vacuum plasma processor for a workpiece processed surface in a chamber includes plural turns. The coil, chamber and workpiece are arranged to produce in the chamber a magnetic flux having substantially greater density in peripheral portions of the coil and chamber than in a center portion of the chamber and coil so a substantially uniform plasma flux is incident on a processed surface of the workpiece.
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Citations
31 Claims
- 1. 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 arcuate segments and 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 arcuate segment, the exterior arcuate segment being radially displaced from the interior arcuate segment, the second terminal being at one of the arcuate segments different from the interior arcuate 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 a center 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 Vpkpk (x) and currents Ipkpk (x) in the coil are approximated by
- space="preserve" listing-type="equation">V.sub.pkpk (x)=V.sup.o.sub.pkpk cos β
(x+x.sup.o)! and I.sub.pkpk (x)=I.sup.o.sub.pkpk sin β
(x+x.sup.o !,
where; x is the linear distance measured from an input terminal of the coil connected to the source, β
is a constant determined by the frequency of the r.f. energization,xo is an offset from zero determined by the impedance of the reactance at the frequency of the r.f. energization, and Vopkpk and Iopkpk are values of the maximum r.f. peak-to-peak voltages and currents in the coil. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- space="preserve" listing-type="equation">V.sub.pkpk (x)=V.sup.o.sub.pkpk cos β
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12. 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 arcuate segments and 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 arcuate segment, the exterior arcuate segment being radially displaced from the interior arcuate segment, the second terminal being at one of the arcuate segments different from the interior arcuate 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 a center portion of the chamber and coil so a substantially uniform plasma flux is incident on a processed surface of the workpiece, the net magnetic field generated by an outermost arcuate turn of the coil and a next outermost arcuate turn of the coil being substantially the same for all angular orientations and radii in the vicinity of the two outermost coils.
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13. 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 arcuate segments and 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 arcuate segment, the exterior arcuate segment being radially displaced from the interior arcuate segment, the second terminal being at one of the arcuate segments different from the interior arcuate 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 a center portion of the chamber and coil so a substantially uniform plasma flux is incident on a processed surface of the workpiece, an outermost arcuate turn of the coil and a next outermost arcuate turn of the coil having a net electrostatic coupling of r.f. voltages to the plasma that is small relative to the net electrostatic coupling of r.f. voltages to the plasma by inner arcuate segments of the coil.
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14. An r.f. vacuum plasma processor for treating a workpiece in a vacuum chamber with a plasma that is adapted to be excited by a source having an r.f. frequency, the processor comprising a coil reactively coupled with a gas in the chamber to excite the gas to the plasma, the coil having first and second excitation terminals and plural turns, the coil being arranged to excite gas in the chamber to a plasma state in response to energization of the coil by the r.f. source, a circuit connected to the excitation terminals and adapted to be connected to the source, the coil having a length between the terminals and the circuit being such that there are substantial current and voltage variations at the r.f. frequency along the coil length, the circuit elements and the coil geometry being such that the current has a relatively low peak-to-peak value in proximity to the excitation terminals and relatively high values in portions of the coil removed from the excitation terminals.
- View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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23. The r.f. vacuum plasma processor of claim 14 wherein the portions of the coil removed from the excitation terminals are peripheral portions of the coil.
- 24. An r.f. vacuum plasma processor for treating a workpiece in a vacuum chamber with a plasma that is adapted to be excited by a source having an r.f. frequency, the processor comprising a coil reactively coupled with a gas in the chamber to excite the gas to the plasma, the coil having first and second excitation terminals and plural turns, the coil being arranged to excite gas in the chamber to a plasma state in response to energization of the coil by the r.f. source, a circuit connected to both of the excitation terminals and adapted to be connected to the source, the coil having a length between the terminals and the circuit being such that there are substantial current and voltage variations at the r.f. frequency along the coil length, both of the excitation terminals being at the interior portions of the coil.
Specification