Nanometer-thick copper films with low resistivity grown on 2D material surfaces

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Thin copper films are crucial for microelectronic interconnects.
• Traditional liner/barrier stacks present limitations in reducing linewidths.
• Two-dimensional (2D) materials offer unique surface properties for advanced applications.

Purpose of the Study:

• To investigate the deposition and properties of thin copper films on MoS2 and WSe2.
• To evaluate the potential of 2D materials as alternatives to conventional liner/barrier stacks.
• To understand the influence of van der Waals epitaxy on copper film growth and characteristics.

Main Methods:

• E-beam deposition of 15 nm copper films on MoS2 and WSe2.
• Growth at room temperature and elevated temperatures (200 °C).
• Resistivity measurements and analysis of film morphology and diffusion.

Main Results:

• Preferential planar growth of continuous polycrystalline copper films via van der Waals epitaxy.
• Low resistivity values observed: 6.07 μΩ-cm (MoS2) and 6.66 μΩ-cm (WSe2) at room temperature.
• WSe2 prevented copper diffusion at 200 °C, unlike MoS2.
• Record-low resistivity of 4.62 μΩ-cm achieved on WSe2 with increased deposition rates.

Conclusions:

• 2D materials exhibit good wettability for copper films.
• Non-sulfur 2D materials like WSe2 show promise for replacing liner/barrier stacks in interconnects.
• The unique properties of WSe2 facilitate improved performance in next-generation interconnects with reduced dimensions.