Electric lamp and discharge devices: systems – Discharge device load with fluent material supply to the... – Plasma generating
Reexamination Certificate
1998-05-28
2001-03-20
Bettendorf, Justin P. (Department: 2817)
Electric lamp and discharge devices: systems
Discharge device load with fluent material supply to the...
Plasma generating
C118S7230IR
Reexamination Certificate
active
06204607
ABSTRACT:
TECHNICAL FIELD
This invention relates to apparatus and methods for producing a plasma useful for treating a substrate surface.
BACKGROUND
Plasmas are useful in a variety of device fabrication processes, including etching, deposition, surface cleaning, and ion implantation. Plasmas may be produced by exciting free electrons in a gas to energy levels that are at or above the ionization energy of the gas molecules. The free electrons may be excited by time-varying electric fields, time-varying magnetic fields, or both. In one approach, described in U.S. Pat. No. 5,435,881, a plasma is produced using a two-by-two or larger array of alternating magnetic poles set proximate to an insulating window in a chamber containing a process gas. The magnetic poles are ferromagnetic core coils driven by a radio-frequency power source. The magnetic poles are uniformly spaced from each other and are configured so that adjacent poles have the same magnitude but opposite magnetic polarity. In operation, the varying magnetic fields between adjacent, opposite polarity poles excite free electrons in the chamber to produce a plasma in the regions of the chamber located between adjacent poles.
SUMMARY
In one aspect, the invention features a plasma source comprising a plasma chamber adapted to receive a gas and having a window transmissive of magnetic flux, and two or more sources of magnetic flux. Each magnetic flux source defines a single magnetic pole adjacent to a plasma chamber window. Each magnetic flux source is laterally spaced apart from any other magnetic flux source so that during operation of the plasma source plasma generation in regions of the plasma chamber immediately adjacent to the magnetic flux sources is substantially greater than plasma generation in regions of the plasma chamber located between the two or more sources.
Each magnetic flux source preferably comprises an antenna for producing magnetic flux in the plasma chamber.
In another aspect, the invention features a plasma source comprising a plasma chamber adapted to receive a gas and having a generally planar window transmissive of magnetic flux, an antenna positioned adjacent to the plasma chamber window, and a ferromagnetic core positioned adjacent to the antenna and configured to concentrate magnetic flux in the vicinity of the antenna through the plasma chamber window and into the plasma chamber. The antenna and the ferromagnetic core are cooperatively configured to induce in the plasma chamber plasma currents that flow in planes that are substantially parallel to the plasma chamber window.
Embodiments may include one or more of the following features.
Each antenna may comprise an electrically conductive coil. Each electrically conductive coil may be generally cylindrical in shape and may define an axis normal to a plasma chamber window. Each electrically conductive coil may be substantially planar in shape; alternatively, each electrically conductive coil may be constructed to conform to a generally hemispherical surface. Each antenna may also comprise an electrically conductive, generally linear wire.
Each magnetic flux source preferably comprises a ferromagnetic (e.g., a ferrite) core. Each magnetic flux source may comprise a ferromagnetic core formed from a plurality of individual ferromagnetic units loaded in a generally cylindrical container. The plasma source may have a plurality of magnetic flux sources arranged in a generally planar array wherein the lateral spacing between neighboring magnetic flux sources is roughly the same.
In another aspect, the invention features a method of exciting a plasma in a plasma chamber containing a gas and having a window transmissive of magnetic flux. The method comprises introducing a gas into the plasma chamber, and applying radio-frequency energy to two or more laterally spaced apart antennas positioned adjacent to the plasma chamber window to induce in regions of the plasma chamber immediately adjacent to the antenna locations plasma generation that is substantially greater than plasma generation in regions of the plasma chamber located between the two or more antennas.
In yet another aspect, the invention features a method of exciting a plasma in a plasma chamber containing a gas and having a window transmissive of magnetic flux. The method comprises introducing a gas into the plasma chamber, and applying radio-frequency energy to an antenna having a ferromagnetic core positioned adjacent to the plasma chamber window to induce in the plasma chamber plasma currents that flow in planes that are substantially parallel to the plasma chamber window.
Among the advantages of the invention ire the following. Because magnetic coupling between the sources of magnetic flux is not required, each source of magnetic flux may be spaced apart from each other and may be powered independently of the other flux sources. This feature reduces the number of magnetic flux sources needed for a given plasma application. This feature also reduces the complexity of the circuit needed to drive the plasma source by greatly simplifying such design considerations as power distribution and power matching. The reduced number of magnetic flux sources also reduces the material cost, as well as the size and weight, of the plasma apparatus. Furthermore, the region of plasma generation inside the plasma chamber may be increased easily by providing additional magnetic flux sources in an array. The ferromagnetic cores enable the invention to produce a plasma with lower coil current levels, reducing the magnitude of parasitic losses in the circuitry that powers the plasma source.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
REFERENCES:
patent: 4947085 (1990-08-01), Nakanishi et al.
patent: 4948458 (1990-08-01), Ogle
patent: 5122251 (1992-06-01), Campbell et al.
patent: 5198725 (1993-03-01), Chen et al.
patent: 5261962 (1993-11-01), Hamamoto et al.
patent: 5277751 (1994-01-01), Ogle
patent: 5435881 (1995-07-01), Ogle
patent: 5464476 (1995-11-01), Gibb et al.
patent: 5589737 (1996-12-01), Barnes et al.
patent: 5683548 (1997-11-01), Hartig et al.
patent: 5795429 (1998-08-01), Ishii et al.
patent: 5907221 (1999-05-01), Sato et al.
patent: 5998933 (1999-12-01), Shun'ko
Applied Komatsu Technology Inc.
Bettendorf Justin P.
Fish & Richardson
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