Graphene Cap on Copper Interconnects for TDDB and Electromigration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current copper interconnect structures in integrated circuits face reliability issues due to time-dependent dielectric breakdown (TDDB) failure and electromigration, particularly as current density increases, leading to defects like voids and hillocks, which are not adequately addressed by existing CoWP alloy metal caps that can cause current leakage and reduce the lifespan of dielectric layers.
Innovation Solution
A copper interconnect structure with an intrinsic graphene cap is introduced, formed by selectively depositing carbon atoms onto the copper layer, which increases the activation energy and reduces current leakage in dielectric regions, thereby enhancing resistance to electromigration and improving BEOL reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CoWP alloy metal cap is deposited on copper interconnect to reduce electromigration, then electromigration resistance is improved, but current leakage increases and TDDB failure occurs
Solution Approach 1:
The patent changes the material parameter from metallic CoWP alloy to non-metallic graphene, fundamentally altering the electrical conductivity parameter from conductive to insulating, thereby eliminating current leakage while maintaining electromigration protection through the cap structure
Solution Approach 2:
The patent uses graphene, a two-dimensional carbon material with unique properties combining electrical insulation with structural integrity, creating a composite cap structure that provides both electromigration resistance and current leakage prevention simultaneously
2Productivity
If copper interconnect density is increased to improve circuit performance, then speed and efficiency are improved, but current density increases exponentially leading to electromigration
Solution Approach 1:
The patent applies preliminary protective action by depositing the graphene cap on the copper interconnect before electromigration can occur, creating a preventive barrier that counteracts the harmful effects of high current density and enables reliable operation at increased current levels
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 graphene cap increases the mean time to failure of copper interconnects by raising the activation energy, reducing TDDB failure and electromigration, thus improving the overall reliability and lifespan of the interconnect structure.
Implementation Method 1
Carbon atoms are selectively deposited onto a copper layer of the interconnect structure by a deposition process to form a graphene cap
Implementation Method 2
The graphene cap increases the activation energy of the copper, thus allowing for higher current density and increased resistance to electromigration of the copper
Implementation Method 3
By depositing the graphene cap on the copper, the dielectric regions remain free of conductors and, thus, current leakage within the interlayer dielectric regions is reduced
Data Source
AI summary
A copper interconnect structure has an intrinsic graphene cap for improving back end of line (BEOL) reliability of the interconnect by reducing time-dependent dielectric breakdown (TDDB) failure and providing resistance to electromigration. Carbon atoms are selectively deposited onto a copper layer of the interconnect structure by a deposition process to form a graphene cap. The graphene cap increases the activation energy of the copper, thus allowing for higher current density and improved resistance to electromigration of the copper. By depositing the graphene cap on the copper, the dielectric regions remain free of conductors and, thus, current leakage within the interlayer dielectric regions is reduced, thereby reducing TDDB failure and increasing the lifespan of the interconnect structure. The reduction of TDDB failure and improved resistance to electromigration improves BEOL reliability of the copper interconnect structure.