[Paper Review] Microelectronic interconnects based on carbon nanotubes

Franz Kreupl, Andrew Graham+4 more|arXiv (Cornell University)|Oct 25, 2004

Carbon Nanotubes in Composites3 citations

TL;DR

This paper reviews carbon nanotubes (CNTs) as a promising alternative for microelectronic interconnects, highlighting their high electrical conductivity, thermal stability, and mechanical strength. It evaluates CNT-based interconnects' feasibility, focusing on synthesis, integration challenges, and performance potential, concluding that CNTs could overcome limitations of traditional copper interconnects at nanoscale dimensions.

ABSTRACT

Carbon nanotubes have emerged as a possible new material for electronic applications. They show promising characteristics for transistors as well as for interconnects. Here we review their basic properties and focus on the status of nanotubes with respect to their application as interconnects and discuss the challenges facing their integration.

Motivation & Objective

• To evaluate carbon nanotubes (CNTs) as a viable alternative to copper interconnects in advanced microelectronics.
• To identify and analyze the key challenges in integrating CNTs into existing semiconductor manufacturing processes.
• To assess the electrical, thermal, and mechanical properties of CNTs relevant to interconnect applications.
• To review the current state of CNT synthesis and alignment techniques suitable for device integration.
• To determine the performance potential of CNT interconnects in comparison to conventional materials at sub-100 nm scales.

Proposed method

• Systematic review of experimental and theoretical studies on CNT electrical and thermal transport properties.
• Analysis of CNT synthesis methods including chemical vapor deposition (CVD) and plasma-enhanced CVD for controlled growth.
• Evaluation of CNT alignment and integration techniques such as dielectrophoresis and directed assembly.
• Comparison of CNT interconnect performance with copper interconnects using scaling laws and simulation data.
• Assessment of reliability factors including electromigration, thermal stability, and contact resistance.
• Incorporation of data from MRS proceedings and peer-reviewed studies to evaluate real-world feasibility.

Experimental results

Research questions

• RQ1 Can carbon nanotubes outperform copper in terms of electrical conductivity and reliability at nanoscale interconnect dimensions?
• RQ2 What are the dominant technical barriers to integrating CNTs into existing CMOS fabrication processes?
• RQ3 How do CNT interconnects perform under high current densities and thermal stress compared to traditional materials?
• RQ4 What are the most effective methods for aligning and connecting CNTs in a dense, uniform interconnect architecture?
• RQ5 What is the scalability and long-term stability of CNT-based interconnects in real microelectronic devices?

Key findings

• Carbon nanotubes exhibit exceptionally high electrical conductivity, with theoretical values exceeding 10^6 S/cm, making them strong candidates for interconnects.
• CNTs demonstrate superior thermal stability and resistance to electromigration compared to copper, especially at sub-100 nm feature sizes.
• Aligned CNT arrays show promise for achieving low-resistance interconnects, with reported contact resistances below 1 kΩ·μm.
• Challenges in CNT synthesis include achieving high yield, precise alignment, and uniform diameter distribution for consistent performance.
• Integration with existing CMOS processes remains a major hurdle due to high-temperature processing constraints and interface engineering issues.
• Despite progress, no CNT interconnect has yet been implemented in commercial microelectronics, indicating a need for further process optimization.