Self-Forming Sidewall Barrier for Low Resistance Interconnects
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Solution Overview
Problem
Conventional copper (Cu) interconnects experience increased resistance at reduced dimensions, limiting the effectiveness of barrier/metallization combinations in back-end-of-line (BEOL) and middle-of-line (MOL) structures, necessitating the development of new interconnect and contact structures with reduced resistance.
Innovation Solution
The implementation of self-forming sidewall barrier layers in BEOL and MOL interconnect structures, utilizing a conformal liner layer with metal alloys like Co-Mn or Ru-Al, which diffuses to form manganese silicate or aluminum silicate barriers along vertical sidewalls, increasing metal volume and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional barrier/adhesion materials such as TiN and/or TaN are used in Co and Ru interconnects, then adhesion and diffusion barrier functions are achieved, but the space available for interconnect metal is reduced, resulting in overly high resistance at scaled dimensions
Solution Approach 1:
The liner layer containing component B (Mn or Al) automatically forms the diffusion barrier through self-diffusion during annealing, eliminating the need for separate barrier material deposition. The liner layer serves dual purposes: as an adhesion layer and as a source for the diffusion barrier, thereby maximizing metal fill volume while maintaining reliability
Solution Approach 2:
The invention changes the material composition parameter by using metal alloys (Co-Mn, Co-Al, Ru-Mn, Ru-Al) instead of conventional single-element barrier materials. This compositional change enables the liner layer to self-form diffusion barriers through controlled diffusion of component B to the sidewall interface during annealing, reducing resistance while maintaining barrier function
2Object-affected harmful factors
If the interconnect structure uses more metal volume, then resistance is reduced, but the space for metal fill is limited by conventional barrier layer requirements
Solution Approach 1:
The liner layer serves multiple functions: adhesion, diffusion barrier formation through self-diffusion, and electromagneticigration barrier formation. This multi-functionality eliminates the need for separate barrier layers, maximizing the volume available for low-resistance metal fill
Solution Approach 2:
The invention uses composite metal alloy liners (Co-Mn, Co-Al, Ru-Mn, Ru-Al) that combine the properties of both components: component A (Co or Ru) provides adhesion and structural integrity, while component B (Mn or Al) diffuses to form the diffusion barrier, creating a functional composite structure
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
This approach effectively lowers interconnect resistance by increasing metal volume and forming efficient diffusion and electromigration barriers, enhancing the performance of BEOL and MOL structures.
Implementation Method 1
annealing the interconnect structure under conditions sufficient to form a barrier layer including the component B along the vertical sidewalls of the at least one feature by diffusing the component B from the conformal liner layer to a sidewall interface between the interconnect structure and the dielectric
Data Source
AI summary
BEOL and MOL interconnect structures with a self-forming sidewall barrier layer are provided. In one aspect, a method of forming an interconnect structure includes: patterning a feature(s) in a dielectric; selectively forming a metal layer at a bottom of the at least one feature; depositing a liner layer lining the feature(s), wherein the conformal liner layer includes a metal alloy AB; depositing a metal onto the liner layer to form the interconnect structure; and annealing the interconnect structure under conditions sufficient to form a barrier layer including the component B along vertical sidewalls of the feature(s). A method of forming an interconnect structure including a via and a trench on top of the via is also provided, as is an interconnect structure.