Deposition of tungsten films from W(CO)6

Details Deposition of tungsten films from W(CO)6 Deposition of tungsten films from W(CO)6

2000-07-31

2001-04-17

Niebling, John F. (Department: 2812)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S682000, C438S683000, C438S934000, C438S974000

Reexamination Certificate

active

06218301

ABSTRACT:

BACKGROUND OF THE DISCLOSURE
1. Field of the Invention
The invention relates to a method of tungsten film deposition and, more particularly, to a method of forming a tungsten film having good film morphology and low resistivity.
2. Description of the Background Art
In the manufacture of integrated circuits, tungsten (W) films are often used as contact metallization or plug metallization for aluminum (Al) interconnect schemes. Tungsten (W) films may also be used as a diffusion barrier for copper (Cu) metallization.
Tungsten layers are typically formed using chemical vapor deposition (CVD) techniques. For example, tungsten may be formed by thermally decomposing a tungsten-containing precursor. For example, W may be formed when tungsten hexafluoride (WF
6
) decomposes.
However, when tungsten films formed from the decomposition of WF
6
, are deposited on oxides (e.g., silicon dioxide (SiO
2
)) poor film morphology may occur. The morphology of a film refers to its thickness, film continuity, surface roughness, and grain structure. For example, tungsten films formed on silicon dioxide (SiO
2
) from the thermal decomposition of WF
6
typically may have a discontinuous film morphology. Such discontinuous film morphology is undesirable because it may affect the electrical characteristics of the tungsten film increasing the resistivity thereof.
Therefore, a need exists in the art for a method of forming tungsten films having good film morphology and low resistivity.
SUMMARY OF THE INVENTION
A method of forming tungsten films on oxide layers is provided. The tungsten films are formed on the oxide layers by treating the oxide using a silane based gas mixture followed by the thermal decomposition of a W(CO)
6
precursor. After the W(CO)
6
precursor is thermally decomposed, an additional layer of tungsten may be optionally formed thereon from the thermal decomposition of tungsten hexafluoride (WF
6
).
The tungsten film formation is compatible with integrated circuit fabrication processes. In one integrated circuit fabrication process, the tungsten film is used as a barrier layer for copper metallization (Cu). For a copper metallization process, a preferred process sequence includes providing a substrate having a dielectric material (e.g., oxide) thereon. The dielectric material has vias therein. A tungsten film is formed on the dielectric material by treating the dielectric material using a silane based gas mixture followed by the thermal decomposition of a W(CO)
6
precursor. After the tungsten film is formed on the dielectric material, the integrated circuit structure is completed by filling the vias with a conductive material, such as, for example, copper (Cu).


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