Copper Interconnect Barrier Structure for Electro-Migration Resistance
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Solution Overview
Problem
The increasing density of integrated circuits is limited by RC delay, which can be mitigated by using copper interconnects and low-k dielectrics, but electro-migration causes copper diffusion and void formation, necessitating effective diffusion barriers.
Innovation Solution
A dielectric barrier layer with a metal-containing interfacial layer is formed over copper-containing metal interconnects, enhancing adhesion and electro-migration resistance, comprising a composition like MxOyNz with specific metal components and thickness ranges, and formed using deposition processes such as PECVD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If copper is used for metal interconnect structures to reduce RC delay, then circuit performance is improved, but electro-migration causes copper diffusion and void formation
Solution Approach 1:
A dielectric barrier layer is introduced as an intermediary between the copper interconnect and the surrounding environment. This barrier layer prevents direct interaction between copper atoms and the dielectric material, blocking copper diffusion while maintaining electrical connectivity and mechanical integrity of the interconnect structure.
Solution Approach 2:
The dielectric barrier layer is formed as a composite structure containing a metal-containing interfacial layer (such as titanium nitride, tantalum nitride, or tungsten nitride) combined with dielectric materials. This composite structure provides both mechanical support and electro-migration resistance, combining the benefits of metallic adhesion layers with dielectric barrier properties.
2Reliability
If diffusion barriers are added to prevent copper diffusion, then electro-migration resistance is improved, but device complexity increases
Solution Approach 1:
The dielectric barrier layer serves multiple functions simultaneously: it acts as a diffusion barrier to prevent copper migration, provides mechanical support for the interconnect structure, enables planarization for subsequent processing steps, and offers adhesion between different layers. This multi-functionality reduces the need for separate dedicated barrier layers and other structural elements.
Solution Approach 2:
The diffusion barrier function is merged with the dielectric layer that already exists in the interconnect structure. Instead of adding a separate barrier layer on top of the copper interconnect, the barrier functionality is integrated into the dielectric material itself, combining two functions into a single structural element.
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 solution effectively inhibits electro-migration and improves the operating lifetime of integrated circuit devices by providing superior adhesion and resistance to copper diffusion, maintaining circuit performance.
Implementation Method 1
Electro-migration is typically mitigated using diffusion barriers. Diffusion barriers are generally provided between copper and adjacent structures.
Implementation Method 2
Incorporating metal within the interfacial layer improves adhesion of the dielectric barrier layer to copper lines
Data Source
AI summary
The present disclosure relates to an integrated circuit. The integrated circuit includes a conductive interconnect disposed on a dielectric over a substrate. An interfacial layer is arranged along an upper surface of the conductive interconnect. A liner is arranged along a lower surface of the conductive interconnect. The liner and the interfacial layer surround the conductive interconnect. A middle layer is located over the interfacial layer and has a bottommost surface over the dielectric. A bottommost surface of the interfacial layer and the bottommost surface of the middle layer are both above a top of the conductive interconnect.