Coating processes – Coating by vapor – gas – or smoke – Metal coating
Reexamination Certificate
2000-09-15
2002-09-03
Chen, Bret (Department: 1762)
Coating processes
Coating by vapor, gas, or smoke
Metal coating
C427S255700
Reexamination Certificate
active
06444263
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates in general to the field of semiconductor electronic devices, and more particularly to an improved method for deposition of a material, such as cobalt, with a chemical-vapor deposition process while suppressing premature gas-phase decomposition of the precursor material.
BACKGROUND OF THE INVENTION
The use of copper metalization for microelectronic semiconductor integrated circuit chip interconnects provides a number of advantages over aluminum metalization, including reduced interconnect propagation delays, reduced cross talk, and higher interconnect current densities with extended electromigration lifetime. Of the methods available for deposition of copper, chemical-vapor deposition (CVD) provides a number of advantages, including the capability for fully vacuum cluster integrated deposition of diffusion barrier and copper layers through cluster tool equipment, excellent gap-fill characteristics for high-aspect ratio via holes and trenches, excellent step coverage, compatibility with single and dual damascene processing, and a relatively low thermal budget for compatibility with low-k organic inter-level/inter-metal dielectrics. However, copper deposited by CVD tends to have poor adhesion when deposited on a substrate, such as on a diffusion barrier, making its incorporation in device structures difficult. For instance, poor copper adhesion often results in delamination of copper layers from underlying barrier layers during chemical-mechanical polishing (CMP) and other fabrication steps.
One solution to the problem of poor adhesion of CVD copper layers is the use of a CVD cobalt glue layer between the CVD copper and barrier layers. This adhesion technique is described in greater detail in U.S. patent application Ser. No. 09/219,147, filed Jul. 10, 1998, now U.S. Pat. No. 6,294,836, entitled “SEMICONDUCTOR CHIP INTERCONNECT BARRIER MATERIAL AND FABRICATION METHOD,” and U.S. patent application Ser. No. 09/518,294, filed Mar. 3, 2000 entitled “MICROELECTRONIC INTERCONNECT MATERIAL WITH ADHESION PROMOTION LAYER AND FABRICATION METHOD, both developed by and commonly assigned to CVC Products, Inc., and each of which are incorporated herein by reference. CVD cobalt is commonly deposited by using carbonyl precursors because carbonyl precursors tend to deposit cobalt films that are relatively carbon free. For instance, carbonyl precursors provide carbon impurity levels typically below five percent while alternative precursors, such as Cp
2
Co and CpCo(CO)
2
generally include greater than ten percent carbon impurity levels. However, CVD cobalt processes with carbonyl precursors tend to have poor process repeatability and uniformity and can generate particulates that result in process drift over time. For instance, one typical set of process conditions for deposition of cobalt with a carbonyl precursor is: 1 sccm of Co(CO)
3
NO carbonyl precursor transported by 15 sccm of He carrier gas, 1500 sccm of H
2
, 15 sccm of backside Ar in a 2 Torr chamber pressure and a 400° C. wafer temperature. For these typical process conditions, a significant process drift and a soot-like particulate formation occurs on the showerhead and chamber walls, impacting the repeatability of the deposition process over multiple process cycles.
SUMMARY OF THE INVENTION
Therefore a need has arisen for a method for chemical vapor deposition of a material on a substrate with improved process repeatability and reduced process drift.
A further need exists for a method for chemical vapor deposition of cobalt using carbonyl precursors with good process repeatability. While maintaining process equipment chamber cleanliness.
A further need exists for a method for chemical vapor deposition of a copper layer on a substrate with improved adhesion provided by a cobalt glue layer.
In accordance with the present invention, a method for deposition of a material on a substrate is provided that substantially eliminates or reduces disadvantages and problems associated with previously developed methods of chemical-vapor deposition with a precursor. Deposition of the material onto the substrate occurs with improved repeatability by suppression of the premature gas-phase decomposition of the precursor due to the addition of decomposition by-products to the precursor during deposition of the material.
More specifically, in one embodiment, repeatability of deposition of a material with carbonyl precursors is improved by the addition of carbon monoxide (CO) to the carbonyl precursor during deposition of the material. Carbon monoxide is a reaction by-product produced during decomposition of carbonyl precursors. The addition of carbon monoxide in the gas phase of deposition process with a carbonyl precursor drives the gas phase reaction in a reverse direction, thereby resulting in suppression of premature precursor decomposition. This suppression aids process repeatability and process equipment cleanliness by reducing process drift and particulate formation on the showerhead and chamber walls.
In one embodiment, the material deposited by the carbonyl precursor is cobalt. For instance, the carbonyl precursor of Co(CO)
3
NO is sublimed in a bubbler with a helium carrier gas and excess hydrogen gas used as the diluent gas. Excess carbon monoxide is added to the flow to suppress premature gas-phase precursor decomposition as the flow proceeds from the showerhead towards the substrate. Suppression of precursor decomposition in the gas phase reduces particulate formation, resulting in repeatable deposition of a high quality cobalt film on the substrate. The cobalt film provides an excellent and commercially-viable glue layer to support deposition of copper on the substrate with good adhesion.
The present invention provides a number of important technical advantages. One important technical advantage is the deposition of a material with a precursor having improved process repeatability. The addition of a precursor decomposition by-product to the precursor flow in the gas phase advantageously suppresses premature decomposition of the precursor, thereby reducing particulate formation on the showerhead and chamber walls. Reduced contaminants in the process chamber provide reduced process drift and result in consistent deposition of high quality films of material in a repeatable manner over many wafer runs.
Another important technical advantage of the present invention is provided by the addition of carbon monoxide to the flow of a carbonyl precursor for deposition of cobalt. The addition of carbon monoxide, a reaction by-product of carbonyl precursors for cobalt deposition, suppresses premature decomposition of the precursor to provide reduced contaminants in the process chamber and the deposited film. In addition, carbon monoxide is a reducing agent which drives down the oxygen content of the CVD cobalt film. Thus, addition of carbon monoxide to a carbonyl precursor flow enables deposition of a smooth, high purity, well adherent CVD cobalt film in a repeatable manner that is well suited for commercial use as a cobalt glue and nucleation layer for CVD copper films.
REFERENCES:
patent: 4510182 (1985-04-01), Cornils et al.
patent: 4789598 (1988-12-01), Howard et al.
patent: 4792378 (1988-12-01), Rose et al.
patent: 4825809 (1989-05-01), Mieno
patent: 4929468 (1990-05-01), Mullendore
patent: 4938999 (1990-07-01), Jenkin
patent: 4948623 (1990-08-01), Beach et al.
patent: 4965656 (1990-10-01), Koubuchi et al.
patent: 4970093 (1990-11-01), Sievers et al.
patent: 5082542 (1992-01-01), Moslehi et al.
patent: 5085731 (1992-02-01), Norman et al.
patent: 5098516 (1992-03-01), Norman et al.
patent: 5112448 (1992-05-01), Chakravorty
patent: 5171610 (1992-12-01), Liu
patent: 5231751 (1993-08-01), Sachdev et al.
patent: 5268034 (1993-12-01), Vukelic
patent: 5312509 (1994-05-01), Eschbach
patent: 5354712 (1994-10-01), Ho et al.
patent: 5453124 (1995-09-01), Moslehi et al.
patent: 5464656 (1995-11-01), Verkade
patent: 5594278 (1997-01-01), Uchiyama
patent: 5595606 (1997-01-01), Fujikawa
patent: 5624498 (1997
Bubber Randhir S.
Gopinath Sanjay
Moslehi Mehrdad M.
Omstead Thomas R.
Paranjpe Ajit P.
Baker & Botts L.L.P.
Chen Bret
CVC Products Inc.
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