Self-Aligned Via Barrier Structure for Ru Interconnect Reliability
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Solution Overview
Problem
The integration of copper-based interconnect structures in advanced ICs faces challenges such as increased resistance, poor electro-migration performance, and voids during fabrication, particularly as IC feature sizes shrink below 20 nm, necessitating improved methods for forming metal vias like Ruthenium (Ru) that prevent corrosion and maintain structural integrity.
Innovation Solution
A method involving a chemical pre-clean using a metal halide to form a self-aligned barrier structure in-situ, followed by a hydrogen plasma clean to remove metal oxides, which reduces necking and critical dimension shrinkage, and prevents kinking, thereby enhancing the reliability and efficiency of the Ru via formation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If copper-based interconnect structures are used in multilayer interconnect features, then manufacturing cost is reduced, but resistance increases and electro-migration performance deteriorates
Solution Approach 1:
The patent changes the material parameter from copper to Ruthenium for via structures in advanced technology nodes. This material substitution resolves the contradiction by providing both acceptable resistance characteristics and superior electro-migration performance while maintaining compatibility with existing manufacturing processes through self-aligned barrier formation.
Solution Approach 2:
The patent employs composite material structures combining Ruthenium via fills with self-aligned barrier structures formed from the same deposition process. This composite approach maintains manufacturing efficiency while achieving the reliability required for sub-20nm technology nodes by preventing void formation and ensuring uniform barrier coverage.
2Object-generated harmful factors
If physical Argon pre-clean is used to remove metal oxides, then cleaning effectiveness is improved, but necking and critical dimension shrinkage increase
Solution Approach 1:
The patent replaces the mechanical/physical Argon pre-clean process with a chemical pre-clean approach using metal halides. This substitution eliminates the harmful physical sputtering effects that cause necking and dimension shrinkage while effectively removing metal oxides through chemical reactions, thereby preserving critical dimensions.
Solution Approach 2:
The patent changes the cleaning mechanism from physical (Argon plasma) to chemical (metal halide pre-clean). This parameter change in the cleaning process achieves effective metal oxide removal without the mechanical damage and dimension shrinkage associated with physical cleaning methods.
3Reliability
If additional selective Tungsten deposition steps are added to prevent corrosion, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the barrier structure formation and corrosion prevention functions into a single self-aligned deposition process. By forming the barrier structure in-situ during the Ruthenium deposition process, the patent eliminates the need for separate Tungsten deposition steps while maintaining comprehensive corrosion protection and structural integrity.
Solution Approach 2:
The patent implements self-aligned barrier formation where the barrier structure automatically forms in the correct location and configuration through the deposition process itself. This self-service approach eliminates the need for additional selective deposition steps, reducing process complexity while ensuring reliable corrosion prevention.
4Productivity
If IC feature size is scaled down to increase functional density, then productivity is improved, but manufacturing complexity and processing difficulty increase
Solution Approach 1:
The patent employs self-aligned barrier formation that automatically adapts to scaled dimensions. The barrier structure forms precisely where needed through the deposition process itself, eliminating the need for additional alignment and patterning steps that would compound processing complexity at smaller feature sizes.
Solution Approach 2:
The patent changes the barrier formation mechanism to a self-aligned chemical deposition process that is inherently scalable. This approach maintains manufacturing feasibility at sub-20nm nodes by avoiding process steps that become prohibitively complex at smaller dimensions.
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 forms a self-aligned barrier structure that prevents corrosion and maintains structural integrity, reducing processing costs and time, while improving the performance and yield of metal vias in advanced ICs by eliminating the need for additional expensive steps like selective Tungsten deposition and physical Argon pre-clean.
Implementation Method 1
The via is pre-cleaned with a metal halide before a second metal is deposited into the via. The metal halide pre-clean forms a metal used for a barrier structure on the contact structure in-situ.
Implementation Method 2
An interface of the barrier structure is cleaned with a hydrogen plasma clean.
Data Source
AI summary
An IC structure includes a transistor, a source/drain contact, a metal oxide layer, a non-metal oxide layer, a barrier structure, and a via. The transistor includes a gate structure and source/drain regions on opposite sides of the gate structure. The source/drain contact is over one of the source/drain regions. The metal oxide layer is over the source/drain contact. The non-metal oxide layer is over the metal oxide layer. The barrier structure is over the source/drain contact. The barrier structure forms a first interface with the metal oxide layer and a second interface with the non-metal oxide layer, and the second interface is laterally offset from the first interface. The via extends through the non-metal oxide layer to the barrier structure.