Ag-Cu Amorphous Interconnect Films for Sub-20 Nm Resistivity
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Solution Overview
Problem
Conventional metallic thin films, such as Cu and Al, experience a sharp increase in resistivity and reliability issues when scaled below sub-20 nm due to grain boundaries and surface scattering, leading to challenges in developing durable and low-resistive interconnects for semiconductor devices.
Innovation Solution
The development of noble metal-copper metallic glass thin films, specifically Ag-Cu eutectic films, which are deposited using low power DC magnetron sputtering to form amorphous structures with no grain boundaries, resulting in high conductivity and low temperature-dependent resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional metallic thin films (Cu, Al) are scaled down below sub-20 nm, then interconnect width is reduced for higher integration, but resistivity increases sharply due to grain boundary and surface scattering
Solution Approach 1:
The invention changes the structural parameter of the metal film from polycrystalline to amorphous phase, eliminating grain boundaries and thereby reducing electron scattering. This phase transformation allows maintaining low resistivity at sub-20 nm scale while achieving the required small interconnect dimensions for high integration
Solution Approach 2:
The invention uses composite material system of Ag-Cu metallic glass with specific composition ratios, combining the advantages of both metals while achieving amorphous structure. The composite amorphous structure provides both low resistivity and high electro-migration resistance required for scaled interconnects
2Ease of manufacture
If polycrystalline thin films are used, then manufacturing is easier, but electron scattering at grain boundaries generates heat and reduces interconnect lifetime
Solution Approach 1:
The invention changes the microstructural parameter from polycrystalline to amorphous phase through controlled deposition parameters (low power sputtering, specific temperature ranges). This eliminates grain boundaries that cause electron scattering and heat generation, thereby extending interconnect lifetime while maintaining manufacturability through established sputtering techniques
3Volume of moving object
If feature size of nano-scale conductors is reduced, then integration density increases, but electro-migration effect dominates and diminishes device durability
Solution Approach 1:
The invention employs Ag-Cu composite amorphous material where the specific composition ratio creates a metallic glass structure with high electro-migration resistance. This allows reducing conductor feature size for higher integration density while the amorphous composite structure prevents material segregation and maintains device durability
Solution Approach 2:
The invention changes the material phase parameter to amorphous state, which eliminates the grain boundary structures that are prone to electro-migration. The amorphous Ag-Cu alloy maintains structural integrity at reduced feature sizes, preventing the electro-migration effects that would otherwise dominate and reduce device durability
4Reliability
If noble metals are used, then electro-migration resistance improves, but cost increases compared to Cu
Solution Approach 1:
The invention creates an Ag-Cu composite amorphous material that combines the high electro-migration resistance of noble metals (Ag) with the low cost and high conductivity of Cu. The specific composition ratio optimizes the balance between performance and cost, achieving noble metal-level electro-migration resistance at lower overall material cost
Solution Approach 2:
The invention changes the material composition parameter to a specific Ag-Cu ratio in amorphous phase, which provides electro-migration resistance comparable to pure noble metals but at reduced cost due to the inclusion of Cu. The amorphous structure ensures uniform distribution and maximizes the beneficial effects of the composite composition
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 Ag-Cu metallic glass thin films exhibit ultra-low resistivity and high conductivity, independent of temperature, addressing the reliability and durability issues in sub-20 nm interconnects by eliminating grain boundary scattering and maintaining performance across a wide temperature range.
Implementation Method 1
sputtering a noble metal-copper metallic glass thin film under controlled power on the thermal oxide
Data Source
AI summary
An interconnect and a method of making an interconnect between one or more features on a substrate comprises: sputtering a noble metal-copper eutectic thin film under controlled power on an oxide grown or deposited on a substrate; and forming an amorphous alloy structure from the noble metal-copper eutectic thin film in the shape of the interconnect and the interconnect comprising no grain or grain boundaries without temperature sensitive resistivity.