Radiant energy – Ion generation – Field ionization type
Reexamination Certificate
2002-07-23
2004-11-09
Berman, Jack I. (Department: 2881)
Radiant energy
Ion generation
Field ionization type
C250S426000, C250S427000, C250S492210
Reexamination Certificate
active
06815690
ABSTRACT:
This invention relates to an ion source including an electrode(s) that is at least partially coated with a coating. In certain example embodiments, a surface(s) of a cathode and/or anode of an ion source may be at least partially coated with a conductive coating for the purpose(s) of: reducing electrode erosion over time, reducing the required frequency of cleaning, reducing contamination of the substrate, and/or improving ion beam characteristics.
BACKGROUND OF THE INVENTION
Ion beam sources are known in the art. For example and without limitation, see the various ion beam sources of U.S. Pat. Nos. 5,508,368; 5,656,819; 5,888,593; 5,973,447; 6,002,208, 6,037,717; 6,147,354; 6,153,067; 6,238,526; 6,246,059; 6,335,086; 6,338,901; 6,359,388; 6,368,664; and 6,395,333, all of which are hereby incorporated herein by reference.
An ion source is a device that causes gas molecules to be ionized and then focuses, accelerates and/or emits the ionized gas molecules and/or atoms in a beam or the like toward a substrate. Such an ion beam may be used for various purposes including but not limited to cleaning a substrate, etching a substrate, milling off a portion of a substrate, and/or depositing thin film(s) on a substrate.
An ion source discussed in U.S. Pat. No. 6,359,388, for example, includes a steel cathode (which includes iron) defining an ion emitting slit. An anode is arranged adjacent to the slit and the cathode so as to be spaced therefrom. An electric field is generated between the anode and cathode. Electron collisions with a working gas in or proximate the electric field leads to ionization and a plasma is generated. The term “plasma” means a cloud of gas including ions of a material to be accelerated and/or emitted toward a substrate. The plasma expands and fills a region including the ion emitting slit defined by cathode portions. Electrons in an ion acceleration space proximate the slit are propelled by the known E×B drift in a closed loop path within the region of crossed electric and magnetic field lines proximate the slit. An ion beam is thus directed from the slit toward a substrate.
Unfortunately, conventional ion beam sources suffer from the problem that during use the electrode(s) (e.g., cathode and/or anode) erode over time. For example, consider a situation where the cathode (or anode) is made of steel—which includes iron. During use of the ion beam source, exposed surface portions of at least the cathode are prone to erosion.
This type of electrode erosion is problematic for a number of reasons. First, significant erosion of the cathode over time can cause the width of the slit (i.e., the magnetic gap) to significantly change which in turn can adversely affect ion beam processing conditions and lead to non-uniform coatings, etchings, etc. Second, significant eroded material from the cathode (e.g., iron) can make its way onto the substrate and/or into a film being ion beam deposited on the substrate, thereby leading to contamination of the substrate and/or film. This latter problem may be characterized by saying that the exposed steel electrode is sputtered during operation of the ion beam source and an undesirably large amount of sputtered material therefrom makes its way onto the substrate and/or film thereby contaminating the same.
In view of the above, it will be appreciated that there exists a need in the art for an ion source (and/or corresponding method) that enables at least one of the aforesaid problems to be reduced and/or overcome.
BRIEF SUMMARY OF THE INVENTION
An object of certain example embodiments of this invention is to provide an ion source (e.g., of the cold-cathode closed-drift type) that includes at least one electrode (anode and/or cathode) that is coated with a coating.
Certain example embodiments of this invention fulfill one or more of the above-listed objects and/or needs by providing an ion source comprising: an anode and a cathode, with an electric gap defined between the anode and the cathode; and wherein at least one of the anode and cathode is at least partially coated with a conductive coating comprising a metal boride.
Certain other example embodiments of this invention fulfill one or more of the above-listed objects and/or needs by providing an ion source comprising: a conductive anode and a conductive cathode, with an electric gap defined between the anode and the cathode; and wherein the ion source is manufactured so that at least one of the anode and cathode is at least partially coated with a coating comprising a metal boride. In certain example embodiments, the metal boride may be MeB
x
, where Me (metal) is one of Ti, Zr, Ta and Fe.
Certain other example embodiments of this invention fulfill one or more of the above-listed objects and/or needs by providing an ion source comprising: a conductive anode and a conductive cathode, with an electric gap defined between the anode and the cathode; and wherein the ion source is manufactured so that at least one of the anode and cathode is at least partially coated with a conductive coating that has a sputtering yield of no more than about 20% of that of an uncoated anode or cathode.
Certain other example embodiments of this invention fulfill one or more of the above-listed objects and/or needs by providing a method of making an ion beam source, the method comprising: providing an anode and a cathode; coating at least a portion of the anode and/or cathode with a conductive coating characterized by at least one of: (a) the coating comprises a metal boride, (b) the coating has a bulk resistivity of no greater than about 20×10
−5
ohms-cm, (c) the coating has a sputtering yield of no more than about 20% of that of an uncoated anode or cathode; and arranging the anode and cathode so as to define an electric gap therebetween in the ion beam source.
Still further example embodiments of this invention fulfill one or more of the above-listed objects and/or needs by providing a method of making a coated article, the method comprising: providing an ion beam source including an anode and cathode with an electric gap defined therebetween, wherein at least a portion of the anode and/or cathode is coated with a conductive coating that is characterized by at least one of: (a) the coating comprises a metal boride, (b) the coating has a bulk resistivity of no greater than about 20×10
5
ohms-cm, (c) the coating has a sputtering yield of no more than about 20% of that of an uncoated anode or cathode; providing a substrate under or above the ion source; and causing flow of at least one gas through the electric gap between the anode and cathode so as to ionize gas, and wherein ions are directed from the source toward the substrate in order to etch, mill and/or form a film on the substrate.
Still further embodiments of this invention fulfill one or more of the above-listed objects and/or needs by providing a an ion source comprising: a conductive anode and a conductive cathode, with a gap defined between the anode and the cathode; and wherein the ion source is manufactured so that at least one of the anode and cathode is at least partially coated with a coating comprising at least one of: a boride, a nitride, and a carbide.
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Luten Henry A.
Petrmichl Rudolph Hugo
Veerasamy Vijayen S.
Berman Jack I.
Guardian Industries Corp.
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