Semiconductor Via Structure with Nitrogen-Rich Etch Stop Layer
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to form reliable semiconductor devices at increasingly smaller sizes, as the scaling-down process complicates fabrication processes and increases complexity.
Innovation Solution
The method involves forming a nitrogen-rich film as an etch stop layer over a cap layer, which allows the cap layer to remain after etching and prevents the formation of a barrier layer over the bottom surface of the via structure, thereby reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap layer is completely removed during etching to form the via structure, then the barrier layer can be formed over the bottom surface, but the resistance increases and manufacturing efficiency decreases
Solution Approach 1:
The patent applies preliminary action by forming the nitrogen-rich etch stop layer before the etching process to control the etching depth and prevent complete removal of the cap layer. This preliminary protective measure ensures the cap layer remains at the bottom surface, avoiding barrier layer formation and reducing resistance while maintaining manufacturing efficiency.
Solution Approach 2:
The nitrogen-rich etch stop layer serves as an intermediary element between the etching process and the cap layer. It mediates the etching depth by being etched at a different rate than the surrounding materials, automatically stopping the etch before the cap layer is completely removed, thus preserving the low-resistance contact.
2Ease of manufacture
If conventional etching processes are used without selective etch stop layers, then the process is simpler, but the cap layer is completely removed and barrier layers form over the via structure
Solution Approach 1:
The patent changes the chemical composition parameter of the etch stop layer by making it nitrogen-rich, which gives it different etching characteristics compared to the surrounding materials. This parameter change allows the etch stop layer to be selectively etched, controlling the via depth and preventing complete cap layer removal without significantly complicating the manufacturing process.
3Manufacturing precision
If the cap layer is completely removed during etching, then the via structure can be fully formed, but barrier layers form over the bottom surface increasing resistance
Solution Approach 1:
The nitrogen-rich etch stop layer is formed in advance to control the etching process. It acts as a depth marker that stops the etch before the cap layer is completely removed, ensuring precise via formation while maintaining the low-resistance contact by preserving the cap layer at the bottom surface.
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 enhances etching selectivity, allows the cap layer to remain intact, and avoids forming a barrier layer over the via structure, resulting in reduced resistance and improved manufacturing efficiency.
Implementation Method 1
forming a nitrogen-rich film as an etch stop layer over a cap layer, which allows the cap layer to remain after etching
Data Source
AI summary
A semiconductor structure includes a gate structure over a substrate. The structure also includes a source/drain epitaxial structure formed on opposite sides of the gate structure. The structure also includes a contact structure formed over the gate structure. The structure also includes a metal layer formed over the contact structure. The structure also includes a cap layer formed over the metal layer. The structure also includes a first etch stop layer including a metal compound formed over the cap layer. The structure also includes a second etch stop layer including nitrogen formed over the first etch stop layer. The structure also includes a via structure that passes through the first etch stop layer and the second etch stop layer. The bottom surface of the cap layer is level with the bottom surface of the first etch stop layer.