Nitrided Metal Cap Interconnects for Electromigration Resistance
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Solution Overview
Problem
Semiconductor interconnect structures face reliability issues due to electromigration, which causes voids in metal conductors from high current density, leading to circuit failures, especially as device sizes decrease.
Innovation Solution
A method involving the formation of a metal cap on conductive structures within an interconnect dielectric material, followed by a thermal or plasma nitridation process that converts metallic residues into nitrided forms, reducing current leakage and enhancing reliability by creating a nitrided metal cap and dielectric surface region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high current density is used in metal conductors to achieve fast signal transmission, then signal speed is improved, but electromigration causes voids and reliability deteriorates
Solution Approach 1:
The patent applies preliminary anti-action by forming a metal cap on the conductive structure before electromigration damage occurs. This metal cap serves as a protective layer that prevents metal atom diffusion and void formation at the interface between the conductive structure and dielectric material, thereby counteracting the harmful effects of electromigration before they can compromise reliability
Solution Approach 2:
The patent employs composite materials by creating a layered structure consisting of the original conductive structure (e.g., copper) combined with a metal cap layer. This composite interconnect structure leverages the high conductivity of the copper core while the metal cap provides electromigration resistance, achieving both fast signal transmission and enhanced reliability
2Productivity
If device size is reduced to increase integration density, then productivity is improved, but electromigration effects become more significant and reliability worsens
Solution Approach 1:
The metal cap is formed as a preventive measure before electromigration damage occurs in scaled-down devices. As device dimensions decrease and current density increases, the metal cap provides early protection against accelerated electromigration effects, maintaining reliability in high-density integrated circuits
3Reliability
If metal cap is formed to reduce electromigration, then reliability is improved, but metallic residues form on dielectric surface causing current leakage
Solution Approach 1:
The patent applies the extraction principle by selectively removing metallic residues from the dielectric material surface using a stripping process. This removes the harmful conductive residues that cause current leakage while preserving the beneficial metal cap layer on the conductive structure that provides electromigration protection
Solution Approach 2:
The patent applies local quality by differentiating the treatment of metal deposits in different locations. The metal cap on the conductive structure is preserved for electromigration protection, while metallic residues on the dielectric surface are removed to prevent current leakage. This selective treatment optimizes both reliability and electrical performance
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 approach results in interconnect structures with improved electromigration resistance, reduced current leakage, and enhanced reliability by converting metallic residues into less conductive nitrided forms, thereby preventing circuit failures.
Implementation Method 1
A thermal nitridization process or plasma nitridation process is then performed which partially or completely converts the metallic residues into nitrided metallic residues
Implementation Method 2
A thermal nitridization process or plasma nitridation process is then performed
Data Source
AI summary
A metal cap is formed on an exposed upper surface of a conductive structure that is embedded within an interconnect dielectric material. During the formation of the metal cap, metallic residues simultaneously form on an exposed upper surface of the interconnect dielectric material. A thermal nitridization process or plasma nitridation process is then performed which partially or completely converts the metallic residues into nitrided metallic residues. During the nitridization process, a surface region of the interconnect dielectric material and a surface region of the metal cap also become nitrided.