Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
2000-08-25
2003-08-05
McPherson, John A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S313000, C430S315000, C430S318000, C430S322000, C427S304000, C427S327000, C427S328000, C156S345420
Reexamination Certificate
active
06602653
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to patterning methods. More particularly, the present invention pertains to the patterning of conductive materials, e.g., copper.
BACKGROUND OF THE INVENTION
Integrated circuits generally include conductive, semiconductive, and insulative materials. Although various metals are used in the metallization of large-scale integrated circuits, many of such metals are difficult to fabricate in fine patterns because of the lack of adequate or suitable etching methods.
For example, copper is a well-recognized conductor. However, few integrated circuits having fine line patterns integrate copper as the conductor for metallization purposes because it is difficult to fabricate fine patterns of copper. There is a strong incentive to incorporate copper as a conductive material in integrated circuits because of its low resistivity, higher melting temperature relative to other metals, and higher electromigration resistance compared with other currently used conductive materials, such as aluminum alloys. As such, incorporation of copper as a conductive material in integrated circuits is desired so as to allow an increase in speed thereof.
One method of using copper for interconnect structures is by patterning the copper using a damascene-type method. Such a method employs the deposition of copper into predefined damascene trenches. Such a process, particularly when adjacent silicon-containing regions, requires that a diffusion barrier/liner layer be used within the trench. However, if the barrier thickness cannot be reduced as trench sizes become smaller, the impact on resistance of the conductor deposited in the trench is significant.
Further, the existing processing methods for patterning certain conductive materials, such as aluminum, are often ineffective for other conductive materials, such as copper. For example, dry etching methods are generally inadequate for providing thin copper conductor patterns.
SUMMARY OF THE INVENTION
The present invention provides patterning methods for patterning conductive materials in the fabrication of integrated circuits. For example, such methods are particularly advantageous for patterning hard to pattern conductive materials, such as copper, palladium, or platinum, or alloys thereof.
A patterning method according to the present invention includes providing a first material and transforming at least a surface region of the first material to a second material. One or more portions of the second material are converted to one or more converted portions of first material while one or more portions of the second material remain. One or more portions of the remaining second material are removed selectively relative to converted portions of first material.
In one embodiment of this method, providing the first material may include forming a first material comprising copper or an alloy thereof. Further, transforming at least a surface region of the first material to a second material may include transforming at least a surface region of the copper or copper alloy to a copper oxide material, e.g., oxidizing the first material.
In another embodiment of this method, converting the one or more portions of the second material may include exposing the one or more portions of the second material to radiation, e.g., using a broadband radiation source and a photo mask or using a scanning laser.
In yet another embodiment of the method, a layer thickness of the one or more converted portions of first material may be increased, e.g., electroplating material on the one or more converted portions of first material or electroless depositing of material on the one or more converted portions of first material. For example, such increasing of the thickness may be performed prior to or after removing the one or more portions of the remaining second material selectively relative to converted portions of first material.
Another patterning method according to the present invention includes providing a layer on a substrate. The layer includes a first chemical composition and is treated to transform at least a region of the layer to a second chemical composition. The layer is then patterned by converting one or more portions of the transformed region including the second chemical composition to one or more converted portions including the first chemical composition with one or more portions including the second chemical composition remaining. The one or more remaining portions including the second chemical composition are removed selectively relative to the one or more converted portions including the first chemical composition.
In various embodiment of this method, for example, the layer including the first composition may be transformed to a metal oxide (e.g., by oxidation), one or more portions of the transformed region including the second chemical composition may be converted to one or more converted portions including the first chemical composition by exposing the one or more portions of the transformed region comprising the second chemical composition to radiation (e.g., using a broadband source and a photo mask or using a scanning laser), the first chemical composition may include an elemental metal which is transformed to a second chemical composition comprising a metal oxide, a thickness of one or more converted portions comprising the first chemical composition may be increased, and the first chemical composition may include copper and the second chemical composition may include copper oxide.
Another method according to the present invention includes providing metal oxide comprising material on a substrate and transforming one or more regions of the metal oxide comprising material to one or more regions of an elemental metal comprising material while leaving one or more remaining regions of the metal oxide comprising material. Thereafter, one or more of the remaining regions of the metal oxide comprising material are removed selectively relative to the one or more regions of the elemental metal comprising material to form conductors on the substrate.
In various embodiments of this method, for example, providing the metal oxide comprising material on a substrate may include forming an elemental metal comprising material on the substrate and oxidizing substantially all of the elemental metal comprising material to form the metal oxide comprising material, the elemental metal comprising material may be one of copper and a copper alloy and the metal oxide comprising material may include copper oxide, transforming the one or more regions of the metal oxide comprising material may include exposing the metal oxide comprising material to radiation, removing the one or more of the remaining regions of the metal oxide comprising material may includes etching one or more of the remaining regions of the metal oxide comprising material with an etchant (e.g., hexafluoroacetylacetone), a thickness of the conductors on the substrate may be increased, and a diffusion barrier material may be used therewith.
A metal conductor patterning method is also described according to the present invention. The method includes providing a layer of copper on a substrate, transforming at least a surface region of the copper to a copper oxide, converting one or more portions of the copper oxide to one or more converted portions of copper while at least other portions of the copper oxide remain, and removing substantially all of the portions of the copper oxide remaining relative to the copper resulting in copper conductors on the substrate. For example, converting the one or more portions of the copper oxide to one or more converted portions of copper may include photoreducing the one or more portions of copper oxide to copper. Further, the method may include increasing a thickness of the copper conductors such as by electroplating material on the one or more converted portions of copper or electroless depositing of material on the one or more converted portions of copper.
Yet another patterning method according to the present invention includes forming d
Geusic Joseph E.
Reinberg Alan R.
Chacko-Davis Daborah
McPherson John A.
Micro)n Technology, Inc.
Mueting Raasch & Gebhardt, P.A.
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