Al-Cu Alloy Interconnects for Electro-Migration Resistance
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving reliable aluminum-based interconnection structures for smaller electronic devices, particularly in ensuring structural integrity and reducing electro-migration issues due to the limitations of existing fabrication techniques such as etching and Damascene processes.
Innovation Solution
The use of aluminum copper alloy interconnection structures with copper manganese, chromium, vanadium, niobium, or titanium alloys, combined with dual damascene techniques and thermal processes to form T-shaped damascene structures, which enhance crystal plane quality and promote metal-to-metal bonding, reducing stress and improving electro-migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If etching process is used to form aluminum interconnection structures, then the fabrication process is simple, but the structural integrity and electro-migration reliability deteriorate
Solution Approach 1:
The patent uses aluminum copper alloy instead of pure aluminum, combining aluminum's conductivity with copper's electro-migration resistance. The alloy composition (e.g., Al-0.5-5.0 wt% Cu) provides both mechanical strength and improved electro-migration reliability while maintaining ease of fabrication through standard semiconductor processes.
Solution Approach 2:
The patent modifies the material composition parameters by introducing copper and other metals (Mn, Cr, V, Nb, Ti) into the aluminum matrix. This changes the physical and chemical properties of the interconnection structure, improving electro-migration resistance and structural integrity while maintaining compatibility with existing etching and CMP processes.
2Reliability
If dual damascene technique is used to form T-shaped structures, then the crystal plane quality and metal-to-metal bonding improve, but the process complexity increases
Solution Approach 1:
The dual damascene process segments the interconnection formation into distinct via and line formation steps. The T-shaped structure is formed by first creating via openings, then forming metal lines that extend into the vias. This segmentation allows optimized processing for each feature type while achieving superior crystal plane quality and metal-to-metal bonding through controlled thermal processes.
Solution Approach 2:
The patent performs preliminary alloy layer formation and thermal processing before final metal deposition. The alloy layers are formed on the sidewalls and bottoms of via openings, and thermal processes are applied in advance to promote diffusion and form high-quality crystal planes. This preliminary action ensures optimal bonding conditions are established before the main metal filling process.
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 proposed solution enhances structural integrity and reduces electro-migration by forming high-quality {111} crystal planes and metal-to-metal bonding, improving the reliability and uniformity of semiconductor devices.
Implementation Method 1
thermal processes to form T-shaped damascene structures, which enhance crystal plane quality and promote metal-to-metal bonding
Implementation Method 2
thermal processes to form T-shaped damascene structures, which enhance crystal plane quality and promote metal-to-metal bonding
Data Source
AI summary
An aluminum interconnection apparatus comprises a metal structure formed over a substrate, wherein the metal structure is formed of a copper and aluminum alloy, a first alloy layer formed underneath the metal structure and a first barrier layer formed underneath the first alloy layer, wherein the first barrier layer is generated by a reaction between the first alloy layer and an adjacent dielectric layer during a thermal process.