Biconvex Metal Wire Interconnects for Low Resistance
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Solution Overview
Problem
As semiconductor interconnect metal feature sizes shrink, scaling diffusion barrier thickness is limited, leading to increased resistance and dielectric flopover risks, necessitating the development of metallization structures with enlarged metal conductor volumes without dielectric flopover for low resistance in advanced technologies.
Innovation Solution
A semiconductor structure with void-free metallization regions of biconvex shape is formed by creating openings in a dielectric material layer, depositing a diffusion barrier and reflow enhancement layer, and filling with metal using reflow anneal, resulting in a biconvex shape with increased volume and reduced wire resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If diffusion barrier thickness is scaled down to minimize interconnect metallic region volume, then volume is reduced, but resistance increases
Solution Approach 1:
The patent applies curvature by forming metallization regions with biconvex cross-sectional shapes instead of conventional rectangular or linear geometries. The biconvex shape features curved sidewalls that bulge outward, increasing the effective metal volume and reducing resistance without requiring proportionally larger footprint dimensions. This geometric transformation directly addresses the contradiction by providing volume expansion through curvature rather than linear scaling.
Solution Approach 2:
The invention transitions from two-dimensional planar interconnect geometries to three-dimensional volumetric structures by creating biconvex metallization regions with enhanced vertical and lateral dimensions. The biconvex shape adds volumetric complexity, effectively utilizing the third dimension to increase conductor volume without proportionally increasing the interconnect footprint, thereby reducing resistance while maintaining compact form factors.
2Reliability
If asymmetric line/space methods are used to reduce BEOL interconnect resistance, then resistance is reduced, but dielectric flopover risk increases
Solution Approach 1:
The biconvex geometry with curved sidewalls distributes electrical fields more uniformly compared to asymmetric linear structures. The curvature eliminates sharp corners and edges that concentrate electric fields, thereby reducing dielectric stress and flopover risks while maintaining low resistance through increased metal volume. This resolves the contradiction by providing a geometric form that simultaneously achieves resistance reduction and dielectric reliability.
3Productivity
If feature sizes are reduced to enable scaling, then device density increases, but resistance increases more rapidly than capacitance
Solution Approach 1:
The biconvex metallization shape compensates for feature size reduction by increasing the effective conductor volume through geometric curvature. Even as overall dimensions shrink to maintain device density, the biconvex geometry ensures adequate metal volume is preserved, keeping resistance from increasing disproportionately. This allows continued scaling while maintaining RC performance.
Solution Approach 2:
The invention changes the geometric parameters of the metallization region from conventional linear dimensions to curved biconvex dimensions. By transforming the cross-sectional geometry to biconvex with outward-curving sidewalls, the effective conductor volume is increased for a given footprint, thereby reducing resistance without requiring larger feature sizes and enabling continued device density improvement.
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 biconvex shape metallization regions achieve a 20-40% increase in volume, significantly reducing wire resistance while avoiding dielectric flopover and electrical shorts, enhancing circuit performance.
Implementation Method 1
a reflow anneal is performed to completely fill a remaining volume of the at least one opening with the metal or metal alloy of the layer of metal or metal alloy
Data Source
AI summary
At least one opening having a biconvex shape is formed into a dielectric material layer. A void-free metallization region (interconnect metallic region and/or metallic contact region) is provided to each of the openings. The void-free metallization region has the biconvex shape and exhibits a low wire resistance.