MoS₂ as an Effective Cu Diffusion Barrier with a Back-End Compatible Process

Area of Science:

• Materials Science
• Semiconductor Technology
• Nanotechnology

Background:

• Diffusion barriers and liners are critical for preventing material interdiffusion in microelectronic devices.
• Current materials like tantalum (Ta) face limitations in performance and compatibility with advanced fabrication processes.
• Molybdenum disulfide (MoS₂) is a 2D material with potential applications in electronics due to its unique properties.

Purpose of the Study:

• To demonstrate molybdenum disulfide (MoS₂) as a superior diffusion barrier and liner material.
• To develop and evaluate a novel microwave plasma-enhanced sulfurization (MW-PES) process for MoS₂ deposition.
• To assess the performance of MW-PES MoS₂ in terms of barrier properties, thermal stability, adhesion, and impact on circuit resistance.

Main Methods:

• Development of a microwave plasma-enhanced sulfurization (MW-PES) technique for direct MoS₂ growth on substrates at low temperatures.
• Characterization of MW-PES MoS₂ films for barrier and liner applications.
• Time-dependent dielectric breakdown (TDDB) measurements to evaluate barrier performance.
• Analysis of adhesion and wettability for copper (Cu) interconnects.
• Assessment of thermal stability and impact on circuit resistance.

Main Results:

• The MW-PES process allows rapid, low-temperature MoS₂ deposition compatible with back-end-of-line (BEOL) fabrication.
• MoS₂ exhibits superior diffusion barrier properties compared to tantalum (Ta), extending device lifetime by approximately 45.2 times.
• MoS₂ demonstrates excellent thermal stability, maintaining its barrier integrity.
• MoS₂ serves as an effective liner, enhancing adhesion and wettability for copper (Cu), reducing surface scattering, and lowering circuit resistance.

Conclusions:

• Molybdenum disulfide (MoS₂) prepared by MW-PES is a highly effective diffusion barrier and liner for microelectronic applications.
• The developed MW-PES process offers a low-temperature, scalable solution for integrating MoS₂ into semiconductor manufacturing.
• MoS₂ presents a promising alternative to conventional materials, enabling improved device reliability and performance.