Study of nitrogen diffusion profile of low resistivity diffusion barrier by resputtering technology

Area of Science:

• Materials Science
• Electrical Engineering
• Semiconductor Manufacturing

Background:

• Fabricating low-resistivity copper diffusion barriers is crucial for integrated circuits beyond 90 nm.
• Tantalum/Tantalum Nitride (Ta/TaN) bilayers are promising but often suffer from high resistivity due to the presence of beta-tantalum (β-Ta).

Purpose of the Study:

• To develop a novel method for producing low-resistivity alpha-tantalum (α-Ta) thin films.
• To improve the performance of copper diffusion barriers in multilevel interconnects.

Main Methods:

• Utilized argon plasma treatment on a TaN substrate to modify the TaN layer.
• Analyzed the resulting Ta/treated-TaN interface using X-ray diffraction (XRD).

Main Results:

• Argon treatment redistributed nitrogen, creating a Ta(N) interface with body-centered cubic (b.c.c.) α-Ta(N) grains.
• Achieved low resistivity by promoting the formation of the α-Ta phase.
• This method differs from conventional sputtering deposition techniques.

Conclusions:

• Argon plasma treatment offers a new route to fabricate low-resistivity α-Ta films for diffusion barriers.
• Controlling nitrogen concentration is key to achieving the desired α-Ta phase and low resistivity.
• This advancement can enhance the reliability and performance of advanced integrated circuits.