Copper Interconnection Diffusion Barrier for Aluminum Bonding
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Solution Overview
Problem
The reduction in width and thickness of metal interconnections in semiconductor devices leads to increased electrical resistance, and the use of copper interconnections results in oxidation issues during wire bonding, requiring additional processing steps and potentially degrading the reliability due to metal atom diffusion when replacing copper with aluminum interconnections.
Innovation Solution
A method involving the formation of a first diffusion barrier layer on a copper interconnection using materials like aluminum, zirconium, or silicon, followed by a second metal interconnection, which prevents metal atom diffusion and allows for a simplified metallization process without void formation, using layers such as titanium nitride or tantalum nitride to enhance the diffusion barrier effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper interconnection is used to reduce electrical resistance, then electrical resistance is reduced, but oxidation occurs during wire bonding process
Solution Approach 1:
A diffusion barrier layer is introduced as an intermediary between the copper interconnection and the aluminum bonding pad. This barrier layer prevents direct contact between copper and aluminum, stopping the diffusion of copper atoms into the aluminum that would cause void formation. The barrier layer thus mediates the interaction between the two metal layers, allowing both low-resistance copper interconnection and reliable aluminum bonding pad coexistence.
2Object-affected harmful factors
If aluminum bonding pad is formed on copper interconnection using conventional dual damascene technique, then oxidation is prevented, but process complexity increases
Solution Approach 1:
The invention extracts and removes the complex multi-layer diffusion barrier structure (titanium layer, titanium nitride layer) from the conventional dual damascene process. Instead, a single simplified diffusion barrier layer is formed directly on the copper interconnection before depositing the aluminum bonding pad. This extraction of unnecessary layers simplifies the metallization process while maintaining oxidation prevention and diffusion barrier functionality.
3Adaptability or versatility
If copper interconnection width and thickness are reduced for higher integration, then device integration is improved, but electrical resistance increases
Solution Approach 1:
The invention creates a composite metal interconnection structure consisting of copper interconnection, diffusion barrier layer, and aluminum bonding pad. This composite structure combines the low-resistance properties of copper with the oxidation-resistant and bondable properties of aluminum. The diffusion barrier layer acts as an interface that prevents detrimental interactions between the two metals, enabling the composite structure to achieve both low resistance and high reliability in highly integrated devices.
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 reduces electrical resistance, prevents oxidation, and simplifies the metallization process by maintaining the reliability of copper interconnections while allowing for the formation of aluminum bonding pads without voids, thus enhancing the overall performance and reliability of semiconductor devices.
Implementation Method 1
forming a first diffusion barrier layer on the exposed first metal interconnection
Data Source
AI summary
Methods of forming a metal interconnection structure are provided. The methods include forming an insulating layer on a semiconductor substrate including a first metal interconnection. The insulating layer is patterned to form an opening that exposes the first metal interconnection. A first diffusion barrier layer is formed on the exposed first metal interconnection. After forming the first diffusion barrier layer, a second diffusion barrier layer is formed on the first diffusion barrier layer in the opening, the second diffusion barrier layer contacting a sidewall of the opening. A second metal interconnection is formed on the second diffusion barrier layer.