Metal Interconnect Doping for Self-Formed Diffusion Barriers
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Solution Overview
Problem
Existing semiconductor devices face challenges with increased line resistance, electromigration, stress migration, and time-dependent dielectric breakdown due to the presence of diffusion barrier layers in metal interconnect structures, which are not scalable and lead to reliability issues as feature sizes shrink.
Innovation Solution
Introduce dopants of zinc, indium, or gallium through chemical vapor deposition at elevated temperatures to form self-formed barrier layers between the liner and dielectric layers, enhancing diffusion barrier properties with minimal resistivity impact, and optionally forming protective layers to prevent oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diffusion barrier layers are used in metal interconnect structures, then resistance to electromigration and stress migration is improved, but line resistance increases and reliability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the barrier layer by doping with zinc, indium, or gallium elements. This modifies the electrical and mechanical properties of the barrier layer, achieving lower line resistance while maintaining or improving resistance to electromigration and stress migration through altered material parameters rather than changing the structural configuration
Solution Approach 2:
The patent creates a composite barrier layer by combining traditional barrier materials with dopant elements (zinc, indium, or gallium). This composite structure integrates the diffusion barrier properties of the base material with the electrical conductivity enhancement and stress resistance provided by the dopant elements, resolving the contradiction between barrier functionality and electrical performance
2Productivity
If feature sizes are reduced to improve device scaling, then device density increases, but diffusion barrier layers become less effective and reliability decreases
Solution Approach 1:
The patent modifies the material parameters of the barrier layer through doping, which changes the fundamental properties of the barrier material. This allows the barrier layer to maintain or enhance its effectiveness even as feature dimensions are reduced, enabling continued device scaling without compromising barrier functionality at smaller dimensions
3Device complexity
If self-formed barrier layers are formed without annealing, then process complexity is reduced, but dopant diffusion and barrier layer formation may be insufficient
Solution Approach 1:
The patent combines the doping process with the barrier layer formation process into a single integrated step. The dopant is introduced during the deposition process itself, eliminating the need for separate annealing steps while ensuring adequate dopant diffusion and barrier layer formation through the combined process mechanism
Solution Approach 2:
The barrier layer forms self-formed through the doping process without requiring external annealing treatment. The dopant atoms automatically diffuse and react during the deposition process to create the barrier structure, making the system self-organizing and eliminating the need for additional processing steps
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 self-formed barrier layers improve resistance to electromigration and stress migration while maintaining low electrical resistance, thus enhancing the reliability and performance of metal interconnect structures.
Implementation Method 1
depositing, by chemical vapor deposition (CVD), a precursor containing zinc, indium, or gallium on the liner layer at an elevated temperature
Implementation Method 2
thereby causing the liner layer to be doped with a dopant of zinc, indium, or gallium
Implementation Method 3
forming, at an interface between the liner layer and the dielectric layer while the substrate is exposed to the elevated temperature, a self-formed barrier layer comprising a reaction product between the dielectric layer and the dopant
Implementation Method 4
forming, at exposed surfaces of the liner layer, a self-formed protective layer comprising zinc oxide, indium oxide, or gallium oxide
Data Source
AI summary
A metal interconnect structure is doped with zinc, indium, or gallium using top-down doping processes to improve diffusion barrier properties with minimal impact on line resistance. Dopant is introduced prior to metallization or after metallization. Dopant may be introduced by chemical vapor deposition on a liner layer at an elevated temperature prior to metallization, by chemical vapor deposition on a metal feature at an elevated temperature after metallization, or by electroless deposition on a copper feature after metallization. Application of elevated temperatures causes the metal interconnect structure to be doped and form a self-formed barrier layer or strengthen an existing diffusion barrier layer.