Low electron temperature, edge-density enhanced, surface wave plasma (SWP) processing method and apparatus
A surface wave plasma (SWP) source couples microwave (MW) energy into a processing chamber through, for example, a radial line slot antenna, to result in a low mean electron energy (T e ). An ICP source, is provided between the SWP source and the substrate and is energized at a low power, less than 100 watts for 300 mm wafers, for example, at about 25 watts. The ICP source couples energy through a peripheral electric dipole coil to reduce capacitive coupling.
1. A method of enhancing uniformity of a plasma at a wafer surface without increasing electron temperature of the plasma in the vacuum processing of a substrate, comprising:
supporting a substrate for processing at one end of a vacuum processing chamber with a surface thereof facing a processing space in the vacuum processing chamber;
coupling energy into the processing space within the vacuum processing chamber from a first plasma source at an end of the vacuum processing chamber opposite the substrate and having a tendency to produce a center-dense plasma over the substrate surface; and
inductively coupling, from an antenna of a second plasma source with the antenna extending around the perimeter of the vacuum processing chamber and positioned in a plane extending through the processing space over the surface of the substrate, RF energy at a low power level of less than 100 watts where the substrate has a diameter of 300 millimeters or less and of less than 300 watts where the substrate has a diameter of more than 300 millimeters.
2. The method of claim 1 wherein:
the first plasma source is a surface wave plasma source;
the coupled energy from the surface wave plasma source is microwave energy coupled into the processing space from a radial line slotted antenna of the surface wave plasma source or from any microwave surface wave coupling mechanism.
3. The method of claim 1 wherein:
the first plasma source is a surface wave plasma source;
the coupled energy from the surface wave plasma source is microwave energy coupled into the processing space from a surface wave launcher.
4. The method of claim 1 wherein:
the antenna around the perimeter from which the RF energy is inductively coupled is a multiple winding coil, and the RF energy is inductively coupled therefrom and through a Faraday shield into the chamber at the periphery thereof.
5. The method of claim 1 wherein:
the inductive coupling of RF energy is at the low power level of from 10 watts to 50 watts.
6. The method of claim 1 wherein:
the inductive coupling of RF energy is at the low power level of about 25 watts.
7. The method of claim 1 wherein:
the antenna around the perimeter from which the RF energy is inductively coupled is a multiple winding coil having an innermost central winding maintained at approximately zero potential at all phases, with windings wound in opposite directions on opposite sides thereof and at increasing radii to terminal ends thereof.
8. The method of claim 1 wherein:
the first plasma source is a surface wave plasma source;
the coupled energy from the surface wave plasma source is microwave energy coupled into the processing space from a radial line slotted antenna.
9. The method of claim 1 further comprising:
adjusting the inductive coupling of the RF energy to adjust a potential difference between an edge of the plasma and a center of the plasma so as to reduce center-dense non-uniformity of the plasma over the surface of the substrate.