Semiconductor Metal Plug Structure with Recess Region
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Solution Overview
Problem
The challenge in semiconductor devices is to ensure reliable electrical connection between upper and lower metal plugs without structural faults, such as cracks in the barrier metal layer, to enhance the electrical reliability of the semiconductor device.
Innovation Solution
The semiconductor device incorporates a first and second metal plug structure with a gap-fill layer and recess region, where the second metal plug fills the second contact hole overlapping the recess region, and a second barrier metal layer is formed on the sidewall and bottom of the second contact hole, using materials like tungsten and copper, and employing processes like CMP and RF etching to prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier metal layer is formed between upper and lower metal plugs to prevent diffusion, then electrical reliability is improved, but the barrier metal layer may crack during manufacturing processes
Solution Approach 1:
The patent divides the contact hole filling process into multiple stages: first forming a lower metal plug with barrier metal layer, then creating a recess region, and finally forming an upper metal plug. This segmentation allows the barrier metal layer to be formed in controlled portions, reducing stress and preventing cracks while maintaining electrical reliability.
Solution Approach 2:
The patent performs preliminary actions by first forming the lower metal plug and barrier metal layer, then creating a recess region before forming the upper metal plug. This preliminary structuring allows subsequent processes to be performed on a stable foundation, preventing barrier metal layer cracking during upper plug formation.
2Reliability
If metal plugs are formed to fill contact holes, then electrical connection is achieved, but stress during filling may cause cracking of the barrier metal layer
Solution Approach 1:
The patent creates a recess region in the insulating layer before forming the upper metal plug. This recess acts as a cushioning structure that absorbs stress during the upper plug formation process, preventing stress transmission to the barrier metal layer and avoiding cracks while ensuring reliable electrical connection.
Solution Approach 2:
The patent applies different structural configurations to different regions: the lower contact hole is filled with lower metal plug and barrier metal layer, while the upper contact hole is formed with a recess region to reduce stress. This local quality differentiation allows each region to be optimized for its specific function, preventing cracking while maintaining electrical connectivity.
3Strength
If a recess region is created and filled with gap-fill layer, then stress on barrier metal layer is reduced, but device structure becomes more complex
Solution Approach 1:
The patent introduces a gap-fill layer as an intermediary material in the recess region. This gap-fill layer serves as a stress-absorbing mediator between the lower and upper metal plugs, protecting the barrier metal layer from cracks while the overall structure remains integrated and functional.
Data Source
AI summary
A semiconductor device includes a first insulating layer on a substrate; a first contact hole passing through the first insulating layer and exposing an upper surface of the substrate; a first barrier metal layer disposed on a sidewall and at a bottom of the first contact hole and a first metal plug disposed on the first barrier metal layer and in the first contact hole. A recess region is between the first insulating layer and the first metal plug. A gap-fill layer fills the recess region; and a second insulating layer is on the gap-fill layer. A second contact hole passes through the second insulating layer and exposes the upper surface of the first metal plug. A second barrier metal layer is on a sidewall and at the bottom of the second contact hole; and a second metal plug is on the second barrier metal layer.