Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2000-06-01
2001-02-27
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S653000, C438S680000, C438S685000
Reexamination Certificate
active
06194310
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to semiconductor technology and more particularly to a method of forming conducting diffusion barriers for semiconductor devices.
Diffusion barriers are commonly used in integrated circuit (IC) fabrication to prevent interdiffusion of metals. For example, a TiN film is used to prevent diffusion of Al into Si at contact regions and along metal lines. As the dimensions of ICs, particularly contact regions and metal lines, continue to shrink, the requirements for the conducting barrier also become more stringent. Thinner barriers are required without substantially increasing resistivity. Barriers also need to be more resistant to diffusion of various new metals, which are being introduced into production processes. One of the metals that is being introduced is copper. Although few diffusion barriers materials effectively block the diffusion of copper, metal nitride and silicon nitride have been shown to act as good barriers against copper diffusion.
To produce effective conductive diffusion barriers, the barriers should preferably act to prevent the diffusion of metals into adjacent structures while simultaneously acting as adequate conductors. The conductive diffusion barrier should provide a suitable balance between its diffusion barrier properties and its conductive properties.
It would be advantageous if a conductive diffusion barrier were available that acted as a good barrier against copper, or other metal, while acting as an adequate conductor.
It would be advantageous if a method of forming a diffusion barrier with the desired characteristics could be provided.
SUMMARY OF THE INVENTION
Accordingly, a method is provided to produce a conducting diffusion barrier that is substantially amorphous, so that no boundary regions extend through the layer to allow for diffusion of metals through the barrier. The method of the present invention comprises the steps of preparing a semiconductor substrate, or wafer, and then forming a barrier layer overlying the semiconductor substrate by depositing a material comprising a refractory metal and nitrogen having a first ratio of elements, and then depositing the same material having a second ratio of elements. The material is considered to be the same material if it has the same basic desired elements, even though the ratio of those elements varies. In another preferred embodiment, the material comprises a refractory metal, silicon, and nitrogen. Preferably, the refractory metal is selected from the group consisting of titanium (Ti), tantalum (Ta) or tungsten (W).
The semiconductor substrate is prepared and placed within a deposition chamber. The deposition chamber is either a chemical vapor deposition (CVD) chamber, a plasma enhanced chemical vapor deposition (PECVD) chamber, or an atomic layer chemical vapor deposition (ALCVD) chamber. A metal nitride precursor is introduced into the chamber along with a nitrogen precursor. The nitrogen precursor can be varied relative to the metal nitride precursor to vary the overall ratio of metal to nitrogen within the diffusion barrier material. As layers of material are deposited the amount of nitrogen precursor is changed to deposit different ratios of elements. The varying ratios of elements throughout the diffusion barrier produces an amorphous diffusion barrier with varying densities through out the barrier. The amorphous structures prevents boundary regions that might otherwise provide a diffusion path for copper or other metals.
Following the deposition process, the diffusion barrier material is annealed, and a layer of metal is deposited to form a conductive path on the semiconductor substrate.
REFERENCES:
patent: 5552341 (1996-09-01), Lee
patent: 5843842 (1998-12-01), Lee et al.
patent: 5899740 (1999-05-01), Kwon
patent: 5939787 (1999-08-01), Lee
patent: 5942799 (1999-08-01), Danek et al.
patent: 6066554 (2000-05-01), Kim et al.
patent: 6096640 (2000-08-01), Hu
Article entitled, “CVD TiN and Hybrid Barriers for Back-end Copper Interconnect Technology”, by A. Jain, et al., Conference Proceedings ULSI XIII, 1998 Materials Research Society, pp. 41-47.
Article entitled, “CVD Copper Barriers” by Timothy E. Levine, et al., Conference Proceedings ULSi XIII, 1998 Materials Research Society, pp. 95-101 (no date).
Article entitled, “Density Oscillation in Sputtered Tantalum Nitride Barrier Metal Thin Films”, by Yanjun Ma et al., Conference Proceedings ULSI XIV—1999 Materials Research Society, pp. 357-363.
Article entitled, “Ta-N as a Cu Diffusion Barrier in Metallization Structures”, by J. Mendonca et al., in Conference Proceedings ULSI XIII—1998 Materials Research Society, pp. 741-745.
Article entitled, “PVD Ta and TaN, Diffusion Barriers and Deposition Techniques for Copper Metallization”, by B. Sun et al., in Conference Proceedings USLI XIII—1998 Materials Research Society, pp. 137-141.
Article entitled, “Process Development and Integration of PVD Ta-Si-N Films for Copper Interconnect Applications”, by R. Venkatraman, in Conference Proceedings ULSI XIII—1998 Materials Research Society, pp. 63-69.
Article entitled, “The Use of Tantalum as Contact and Barrier Material from the Silicon Active Regions to the Bond Pads in Copper Metallization Scheme”, by Christian Wenzel et al., in Conference Proceedings ULSI XIII—1998 Materials Research Society, pp. 131-137.
Article entitled, “Barriers for copper interconnections”, by Changsup Ryu et al., published in Apr. 1999 Solid State Technology, pp. 53-56.
Article entitled, “Depositing Diffusion Barriers”, by John Baliga, in Mar. 1997 Semiconductor International, pp. 77-82.
Evans David Russell
Hsu Sheng Teng
Pan Wei
Tweet Douglas James
Gurley Lynne
Krieger Scott C.
Niebling John F.
Rabdau Mathew D.
Ripma David C.
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