Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Reexamination Certificate
1999-05-25
2002-01-08
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
C428S901000, C427S252000, C556S110000, C556S112000
Reexamination Certificate
active
06337148
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to copper precursor compositions and their synthesis, and to the use of such copper precursor compositions for the fabrication of microelectronic device structures, e.g., in the formation of copper-based interconnects in the manufacture of semiconductor integrated circuits, or in otherwise metallizing or forming copper-containing films on a substrate by metalorganic chemical vapor deposition (MOCVD) utilizing such precursor compositions.
2. Description of the Related Art
The process of fabricating semiconductor integrated circuits generally includes the formation of metal interconnect lines. Such metal interconnect lines often are formed from multiple conductive layers. For example, a thin conductive layer (termed a “barrier layer” in this context) may be formed from a metal, a metal nitride or a metal silicide, with a thicker conductive layer of aluminum, copper or other metal deposited over the barrier layer.
Many semiconductor device manufacturers are adopting copper metallization for use in production of microelectronic chips. Copper interconnects offer chip manufacturers a number of advantages, including enhanced circuit speed, improved performance and reduced electro-migration effects. Any of the one or more metal layers (e.g., bulk layer and/or seed layer) of a semiconductor integrated circuit may be formed utilizing a copper-based film. Furthermore, low resistivity, low contact resistance, and reduced RC time delays make copper particularly desirable for use in the metallization of very large scale integration (VLSI) devices.
In order to prevent detrimental effects caused by the interaction of a copper layer with other portions of the integrated circuit, a barrier layer is typically utilized in conjunction with the copper layers. Any of a wide range of barrier materials may be utilized including materials comprising metals, metal nitrides or metal silicides. Exemplary barrier materials include titanium nitride, titanium suicide, tantalum nitride, tantalum silicide, tungsten nitride, tungsten silicide and silicon doped metal nitrides. After the formation of a barrier layer, the copper is deposited on the barrier layer. The initial copper deposition may function as an electrochemical or CVD seed layer, e.g., an adhesive, conducting seed layer, followed by electrochemical plating or CVD of copper, for instance to complete the thin-film interconnect. Alternatively, the copper deposition may be employed to fully deposit the desired amount of copper.
For practical applications, the copper CVD precursors for the metallization composition should remain stable at room temperature and should not decompose at the vaporization temperature (e.g., the temperature required to efficiently vaporize the precursor). Concurrently, however, the precursor must decompose at elevated temperature to form high-purity Cu films on the heated substrate surface. The satisfaction of these parameters requires a delicate balance because the difference between the vaporization temperature and the film growth temperature is typically quite small (~100° C.).
A suitable thermal stability can be realized by using bi-dentate neutral Lewis base ligands such as an ene-one. In this manner, the combination of the two coordination sites can be “fine-tuned.” Further, chelating complexes usually exhibit better stability than monodentate complexes.
Chemical vapor deposition (CVD) of copper provides uniform coverage for the metallization. Liquid CVD precursors enable direct delivery or liquid injection of the precursors into a CVD vaporizer unit. The accurate and precise delivery rate can be obtained through volumetric metering to achieve reproducible CVD metallization during VLSI device manufacturing.
Currently only a few liquid copper precursors are commercially available. These include (hfac)Cu(MHY), (hfac)Cu(3-hexyne), (hfac)Cu(DMCOD) and (hfac)Cu(VTMS), wherein hfac=1,1,1,5,5,5-hexafluoroacetylacetonato, MHY=2-methyl-1-hexen-3-yne, DMCOD=dimethylcyclooctadiene, and VTMS=vinyltrimethylsilane. However, concerns have arisen regarding perfluoro-&bgr;-diketonate ligands, such as hfac, because the fluorine can react on the substrate surface forming a thin interface layer of CuF
2
, leading to poor adhesion and high contact resistances of Cu films on the substrate. Copper CVD precursors with a reduction of fluorine-content or without fluorine are therefore highly desirable. The present invention provides new (&bgr;-diketonate)CuL precursors (wherein L is a coordinating ligand in the (&bgr;-diketonate)CuL complex) with reduced and/or eliminated fluorine content in the complexes having utility in CVD of Cu thin films.
Furthermore, to achieve a reproducible film growth process, liquid precursors are extremely desirable. To date, only a few (hfac)CuL complexes are liquids that satisfy the requirements for CVD precursors. An organic solution prepared from a solid precursor provides a significant opportunity to increase the precursor availability for various purposes. However, it is well known that the solutions of (hfac)CuL complexes display poor stability. For example, a 50% ether solution of (hfac)Cu(MHY) decomposes in a few days at room temperature while the neat precursor is stable for at least 6 months. Therefore, there is a clear need to continuously develop reliable liquid source materials (neat or in a thermally stable chemical solution) for the CVD of Cu thin films. The present invention provides new stable (hfac)CuL precursors compositions and solutions.
As previously noted, the use of various copper precursors in CVD reactors to create copper interconnects in semiconductor integrated circuits, for example, is well known. U.S. Pat. Nos. 5,085,731; 5,098,516; 5,144,049; and 5,322,712 provide examples; and the references cited in these patents provide additional examples of such precursors. New and useful compositions and processes for the production of copper that improve upon, or provide alternatives to, these known compositions are highly desirable.
Copper CVD processes that are suitable for the large-scale manufacture of integrated circuits are extremely valuable to the electronics industry. Towards these ends, Cu CVD is generally used for two purposes: (1) deposition of a conductive thin-film layer as a plating base (“seed”) for electroplating processes; and (2) full-fill deposition of copper interconnects, features and multi-level structures.
There is, therefore, a need in the art for new and improved copper precursors for metallization in the manufacture of integrated circuits and other microelectronic device structures, using techniques such as CVD, plasma-assisted CVD, etc. Further, improved vaporization can lead to greatly improved deposition processes.
It is accordingly an object of the present invention to provide new copper precursors and formulations.
It is another object of the invention to provide methods of forming copper in the manufacturing of integrated circuits and other microelectronic device structures.
It is a further object of the invention to provide metallization technology for forming interconnects and other integrated device structures that overcome the shortcomings and limitations of the prior art, namely robust manufacturing.
It is another object of the invention to provide a method of metallizing or forming copper-containing thin films on a substrate by metalorganic chemical vapor deposition (MOCVD) utilizing such novel copper precursors and solution compositions.
Other objects and advantages of the present invention will be more fully apparent from the ensuing disclosure and appended claims.
SUMMARY OF THE INVENTION
The present invention relates to copper source reagent compositions, and to methods of making, stabilizing and using the same.
In one broad aspect, the present invention relates to novel (&bgr;-diketonate)CuL precursors with increased thermal stability, with reduced fluorine content (relative to various corresponding commercial copper source reagents) and havi
Baum Thomas H.
Xu Chongying
Advanced Technology & Materials Inc.
Chappuis Margaret M.
Hultquist Steven J.
Jones Deborah
Savage Jason
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