Electric lamp and discharge devices: systems – Discharge device load with fluent material supply to the... – Plasma generating
Reexamination Certificate
1997-02-24
2001-05-01
Shingleton, Michael B (Department: 2817)
Electric lamp and discharge devices: systems
Discharge device load with fluent material supply to the...
Plasma generating
C315S011000, C315S111810, C118S7230IR, C118S7230IR, C118S7230AN
Reexamination Certificate
active
06225744
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to plasma sources, and more particularly to induction plasma sources for integrated circuit fabrication.
2. Description of Related Art
Plasma etching is useful in many fields, but particularly in the field of microelectronic fabrication. Microelectronic fabrication of integrated circuits requires mass replication of tightly controlled, submicron-sized features in a variety of materials, as well as selective removal of material without causing damage to sensitive structures and remaining materials. Illustrative application of plasma etching to microelectronic fabrication of integrated circuits includes ion sputter cleaning, dielectric gap filling involving simultaneous chemical vapor deposition (“CVD”) and etch, chemical blanket etchback without resist, and chemical pattern etch with resist.
Various plasma source methods and geometric designs for reactors are known for use in plasma deposition and etching. For example, electron cyclotron resonance (“ECR”) sources are available from Applied Science and Technology, Inc., Woburn, Mass. and from the WAVEMAT Corporation, Plymouth, Mass. Also, wafer cleaning and etching processes have commonly been done with equipment using various cylindrical shaped quartz vessels of various diameters having induction windings of various pitches, either constant or variable, as well as with flat spiral induction windings mounted above the dielectric chamber top plate. Radio frequency (“rf”) diode and triode configurations are also known in which the wafer electrode and possibly other electrodes are powered at 13.56 MHz to produce the plasma.
Physical sputtering, one of several plasma etching mechanisms, involves the removal of material by energetic ions, which cross the sheath and transfer energy and momentum to the material being etched. As implemented on a great many of the prior art inductively coupled cavity and/or diode and triode machines, physical sputtering suffers from a number of disadvantages, including low material removal rate, poor etch uniformity due to poor ion current uniformity, and electrical damage to the substrate from ion bombardment and implantation due to high ion energies. The ECR sources provide improved performance, but with considerably greater complexity than induction-type sources.
Hence, a need continues for plasma source systems that are able to provide good ion density to achieve high etch rates, ion current uniformity to achieve uniform removal of material over large diameter substrates, and operational stability at low pressure to achieve a more uniform ion distribution in the plasma and better directionality of ions in high aspect ratio structures, all in a generally simple machine implementation.
SUMMARY OF THE INVENTION
The present invention achieves high ion density, good ion current uniformity, and stable low pressure operation in a generally simple machine implementation.
In one embodiment of the present invention, an induction plasma source, the induction coil is hemispherical in shape. A chamber into which a substrate may be introduced is disposed inside the induction coil. In a further embodiment, the induction coil follows the contour of a hemispherically shaped vessel, which contains the chamber. In yet a further embodiment, the power source is a low frequency source having a frequency of about 450 KHz and a power in the range of 200-10,000 watts, and the pressure is a low pressure of about 0.1-100 mTorr.
In another group of embodiments the vessel is not hemispherically shaped. The vessel may be in the shape of a spherical section that is less than a full hemisphere, or it may be in the shape of a paraboloid or another shell-shaped geometric form that has a convex outside surface and a concave inside surface. In yet another group of embodiments the spacing between the individual windings of the induction coil is varied, and in some embodiments two or more layers of windings are provided in selected areas of the vessel. These groups of embodiments generally permit adjusting the location in the chamber where the greatest energy absorption and hence plasma creation takes place. In this way the plasma can be shaped to provide a better plasma and improved processing uniformity.
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Benzing Jeffrey C.
Broadbent Eliot K.
Rough J. Kirkwood H.
Tobin Jeffrey A.
Lawrence Don C.
Novellus Systems Inc.
Shingleton Michael B
Skjerven Morrill & MacPherson LLP
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