Patent number 8647978 is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "The present disclosure relates to a semiconductor structure and a method of forming the same. More particularly, the present disclosure relates to a back-end-of-the-line (BEOL) interconnect structure including graphene present on exposed sidewall surfaces and a topmost surface of a copper, Cu, structure.
"Integrated circuits (ICs) typically include a plurality of semiconductor devices and interconnect wiring. Networks of metal interconnect wiring typically connect the semiconductor devices from a semiconductor portion of a semiconductor substrate. Multiple levels of metal interconnect wiring above the semiconductor portion of the substrate are connected together to form a back-end-of-the-line (BEOL) interconnect structure. Within such a structure, metal lines run parallel to the substrate and metal vias run perpendicular to the substrate.
"Two developments in the last decade have contributed to increased performance of contemporary ICs. One such development is the use of copper as the interconnect metal of the BEOL interconnect structure. Copper is advantageous because it has a higher conductivity compared with other traditionally used interconnect metals such, as for, example, aluminum.
"A second development is the employment of low dielectric constant (low k) dielectric materials and/or air gaps within the BEOL interconnect structure. Low k dielectric materials and air gaps have dielectric constants that are lower than those of traditionally used interconnect dielectric materials such as, for example, silicon dioxide.
"One problem of using copper as the metal in the BEOL interconnect structure is that copper is very reactive in air and readily forms a copper oxide. As such, exposed copper surfaces need to be passivated. Typically, a dielectric and/or metallic capping layer are employed in prior art copper-containing BEOL interconnect structures.
"Another problem that arises when copper is used as the metal in the interconnect structure is that copper ions tend to diffuse into the interconnect dielectric material during use. The diffusion of copper ions from the metal feature into the dielectric material causes voids to form within the metal feature of the BEOL interconnect structure. These voids can lead to failure of the IC. As such, a diffusion barrier such as, for example, TiN, is typically used to reduce the diffusion of copper ions into the interconnect dielectric material and thus reduce the electromigration of copper from the metal feature.
"Although various capping layers and diffusion barriers are known in the art, a need exists to provide an alternative material that can provide the same functions as the capping layers and the diffusion barriers mentioned above, yet reduce the resistivity of the copper metal within such BEOL interconnect structures."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "A contiguous layer of graphene is formed on exposed sidewall surfaces and a topmost surface of a copper-containing structure that is present on a surface of a substrate. The presence of the contiguous layer of graphene on the copper-containing structure reduces copper oxidation and surface diffusion of copper ions and thus improves the electromigration resistance of the structure. These benefits can be obtained using graphene without increasing the resistance of the copper-containing structure.
"In one aspect of the present disclosure, a method of forming an interconnect structure is provided. The method of the present disclosure includes forming a sacrificial dielectric material on a surface of a substrate. Next, at least one opening is formed within the sacrificial dielectric material that exposes a portion of the surface of the substrate. A copper-containing structure is formed within the at least one opening and the exposed portion of the surface of the substrate. Remaining portions of the sacrificial dielectric material are removed and thereafter a contiguous layer of graphene is formed on exposed sidewall surfaces and a topmost surface of the copper-containing structure.
"In another aspect of the present disclosure, an interconnect structure is provided. The interconnect structure includes at least one copper-containing structure located on a surface of a substrate. The structure of the present disclosure further includes a contiguous layer of graphene comprising a first portion located on each exposed sidewall surface of the copper-containing structure and a second portion located on a topmost surface of the at least one copper-containing structure, wherein a bottommost surface of the first portion of the contiguous layer of graphene is in contact with the surface of the substrate."
URL and more information on this patent, see: Ott, John A.; Bol, Ageeth A.. Use of
Keywords for this news article include: Electronics, Semiconductor,
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