US 5,707,486 A · Plasma reactor using UHF/VHF and RF triode source, and process

Abstract

A plasma reactor preferably uses a split electrode which surrounds a plasma dome region of the reactor, is driven by high frequency energy selected from VHF and UHF and produces an electric field inside the electrode, parallel to the wafer support electrode. A static axial magnetic field may be used which is perpendicular to the electric field. The above apparatus generates a high density, low energy plasma inside a vacuum chamber for etching metals, dielectrics and semiconductor materials. Relatively lower frequency, preferably RF frequency, auxiliary bias energy applied to the wafer support cathode controls the cathode sheath voltage and controls the ion energy independent of density. Various etch processes, deposition processes and combined etch/deposition processes (for example, sputter/facet deposition) are disclosed. The triode (VHF/UHF split electrode plus RF wafer support electrode) provides processing of sensitive devices without damage and without microloading, thus providing increased yields.

Claims19

Dependent claims

A system for processing a workpiece comprising:

a vacuum processing chamber for the workpiece;
a chamber inlet for introducing process gas into the chamber;
a plurality of electrodes coupling AC electrical energy into the chamber to generate a plasma in the gas, the electrodes comprising a first electrode structure having two separate sections for defining a plasma-generating electrical field, the field being concentrated within a region of the chamber spaced from the workpiece, the field also being principally oriented parallel to the workpiece for preventing ion acceleration from or toward the workpiece, and a second electrode structure adapted to support the workpiece and for modifying a sheath voltage associated with the electrodes and plasma ion energy proximate the workpiece;
first source of AC electrical energy to the first electrode at a first frequency within the range of about 50 MHz to about 800 MHz, and
a second source of AC electrical energy to the second electrode at a second frequency within the range of about 0.1 MHz up to but below about 50 MHz, thereby controlling the sheath voltage and the plasma ion energy.

2 more elements

A system for processing a workpiece in a plasma generated from a gas, comprising:

a vacuum processing chamber for receiving the gas;
a support electrode for supporting the workpiece within the chamber;
a split electrode surrounding a volume of the chamber in parallel spaced relation to the workpiece for capacitively coupling AC electrical energy into the chamber to produce a plasma-inducing electrical field in a selected region of the chamber spaced from the support electrode, to prevent damage to the workpiece, and
a first power supply connected to the split electrode for supplying high frequency AC energy having a frequency in the range of 50-800 MHz to the split electrode and for controlling the power of the energy, to provide selected plasma density and plasma ion current density;
and
a second power supply for applying to the support electrode selected AC electrical energy of lower frequency, in the range 0.1 MHz up to but below 50 MHz, than said capacitively coupled AC electrical energy, and for controlling said selected AC electrical energy applied to the support electrode to control a plasma sheath voltage at the support electrode and an associated plasma ion energy.

3 more elements

Dependencies are inferred from the claim text.

Plasma reactor using UHF/VHF and RF triode source, and process

Life of this patent

Plasma reactor using UHF/VHF and RF triode source, and process

Life of this patent

Abstract

Claims19