Plasma process uniformity across a wafer by controlling RF phase between opposing electrodes
First Claim
Patent Images
1. A method of processing a workpiece in a plasma reactor chamber, comprising:
- coupling, to a plasma in the chamber, power of an RF frequency via a ceiling electrode and coupling, to the plasma, power of at least approximately the same RF frequency via a workpiece support electrode;
providing an edge ground return path; and
adjusting the proportion between (a) current flow through a center RF current path between said electrodes and (b) current flow to the edge ground return path from said electrodes, wherein said adjusting comprises;
(a) determining non-uniformity of radial distribution of plasma ion density in said chamber,(b) performing one of;
(i) responding to a center-high nonuniformity by reducing a phase difference between RF voltages or currents at said ceiling electrode and said workpiece support electrode,(ii) responding to an edge high nonuniformity by increasing a phase difference between RF voltages or currents at said ceiling electrode and said workpiece support electrode.
1 Assignment
0 Petitions
Accused Products
Abstract
A method is provided for processing a workpiece in a plasma reactor chamber. The method includes coupling, to a plasma in the chamber, power of an RF frequency via a ceiling electrode and coupling, to the plasma, power of at least approximately the same RF frequency via a workpiece support electrode. The method also includes providing an edge ground return path. The method further includes adjusting the proportion between (a) current flow between said electrodes and (b) current flow to the edge ground return path from said electrodes, to control plasma ion density distribution uniformity over the workpiece.
22 Citations
20 Claims
-
1. A method of processing a workpiece in a plasma reactor chamber, comprising:
-
coupling, to a plasma in the chamber, power of an RF frequency via a ceiling electrode and coupling, to the plasma, power of at least approximately the same RF frequency via a workpiece support electrode; providing an edge ground return path; and adjusting the proportion between (a) current flow through a center RF current path between said electrodes and (b) current flow to the edge ground return path from said electrodes, wherein said adjusting comprises; (a) determining non-uniformity of radial distribution of plasma ion density in said chamber, (b) performing one of; (i) responding to a center-high nonuniformity by reducing a phase difference between RF voltages or currents at said ceiling electrode and said workpiece support electrode, (ii) responding to an edge high nonuniformity by increasing a phase difference between RF voltages or currents at said ceiling electrode and said workpiece support electrode. - View Dependent Claims (2, 3, 4, 5, 7, 8, 9, 10)
-
-
6. The method of 1 wherein said adjusting comprises bringing said phase difference closer to an angle of zero degrees in order to decrease current flow between the two electrodes and increase current flow to the edge ground return path so as to decrease a center-high non-uniformity in plasma ion density distribution.
-
11. A method of processing a workpiece in a plasma reactor chamber, comprising:
-
coupling, to a plasma in the chamber, power of an RF frequency via a ceiling electrode and coupling, to the plasma, power of at least approximately the same RF frequency via a workpiece support electrode; providing an edge ground return path; determining nonuniformity of radial distribution of plasma ion density in said chamber; and performing one of; (a) responding to a center high nonuniformity by increasing an impedance of a center RF current path between said electrodes relative to impedance of said edge ground return path by adjusting the reactance of a reactive element coupled to one of said electrodes, (b) responding to an edge high nonuniformity by increasing an impedance of said edge ground return path relative to impedance of said center RF current path by adjusting the reactance of a reactive element coupled to one of said electrodes. - View Dependent Claims (12, 13, 14, 15, 16, 20)
-
-
17. A method of processing a workpiece in a plasma reactor chamber, comprising:
-
coupling, to a plasma in the chamber, power of an RF frequency via a ceiling electrode and coupling, to the plasma, power of at least approximately the same RF frequency via a workpiece support electrode; providing an edge ground return path; determining whether radial distribution of plasma ion density in said chamber has a nonuniformity that is one of (i) center high, (ii) edge high; and performing one of; (a) responding to a center high nonuniformity by adjusting the phase angle between the RF currents at the two electrodes to increase impedance of a center RF current path between said electrodes relative to impedance of said edge ground return path, (b) responding to an edge high nonuniformity by adjusting said phase angle to increase impedance of said edge ground return path relative to impedance of said center RF current path if said nonuniformity is edge high. - View Dependent Claims (18, 19)
-
Specification