Dipole-Lined BEOL Wires for Electromigration Resistance
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Solution Overview
Problem
Current back-end-of-line (BEOL) metal vias and lines in integrated circuits suffer from electromigration, which causes dielectric breakdown due to electron escape through low-k dielectric, and existing barrier metals like tantalum nitride face limitations in thickness and resistivity, especially as via size reduces.
Innovation Solution
A dipole liner comprising a rare earth element oxide or oxynitride is used to surround and separate conductive wires from low-k dielectric, inhibiting electromigration by directing a dipole moment from the wire to the dielectric, reducing electron collision and migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TaN liners are used to reduce electromigration and improve Cu adhesion, then barrier properties and adhesion are improved, but the minimum thickness requirement (1-2 nm) increases resistivity impact on Cu lines
Solution Approach 1:
A dipole liner comprising rare earth element oxide or oxynitride is introduced as an intermediary layer between the conductive wire and low-k dielectric. This dipole liner creates a dipole moment that repels electrons from the interface, reducing electromigration without requiring thick barrier metal layers that would increase resistivity.
Solution Approach 2:
The invention changes the physical and chemical parameters of the barrier layer by using rare earth element oxides with specific dipole moments. This allows the barrier to function effectively at much thinner dimensions (sub-nanometer to nanometer scale) compared to conventional TaN liners, thereby reducing the resistivity impact on Cu lines.
2Productivity
If via size is reduced to increase integration density, then device scaling is improved, but there is less space for Cu for same liner size
Solution Approach 1:
By changing to rare earth element oxide materials with appropriate dipole moments, the barrier layer can be made extremely thin while maintaining effective electromigration protection. This enables via size reduction for higher integration density without sacrificing resistivity control, as the dipole liner requires minimal thickness to function.
Solution Approach 2:
The dipole liner provides localized protection at the critical wire-dielectric interface where electromigration occurs, rather than requiring a thick uniform barrier throughout the entire via. This localized quality approach allows maximum Cu fill in the via while maintaining barrier effectiveness.
3Reliability
If 2D materials are used as barriers, then electromigration resistance is improved, but adhesion and growth quality become problematic
Solution Approach 1:
The dipole liner uses rare earth element oxides that can be deposited using standard ALD processes, replacing the need for complex 2D material growth equipment and processes. These materials provide effective electromigration protection without the adhesion and growth quality issues of 2D materials, using well-established manufacturing techniques.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The dipole liner effectively reduces or prevents electromigration by repelling electrons from the wire interface, enhancing the lifetime and performance of BEOL structures.
Implementation Method 1
the dipole liner comprising a dipole... the dipole has a dipole moment that is directed from the conductive wire to the low-k dielectric... repelling electrons from the wire interface
Data Source
AI summary
Methods and related structures and systems for inhibiting electromigration in back-end-of-line metal lines in integrated circuits. Embodiments of the presently disclosed structures comprise a dipole liner comprising a dipole that is positioned between a conductive wire and a low-k dielectric.