Copper-Tungsten Plug Layout for Smaller Reliable Semiconductor Interconnects
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Solution Overview
Problem
The challenge in semiconductor device manufacturing is to reduce chip size while maintaining electrical characteristics, as existing methods often lead to deterioration of electrical performance due to the use of copper interconnection layers which are prone to elution during wet etching processes.
Innovation Solution
The semiconductor device employs a configuration with tungsten-based via plugs and interconnections, including copper interconnection layers formed above and below the via plugs, which are designed to prevent the elution of copper and maintain electrical integrity, allowing for miniaturization without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If copper interconnection layers are used to reduce chip size, then miniaturization is achieved, but copper elution occurs during wet etching processes causing deterioration of electrical characteristics
Solution Approach 1:
A barrier layer is introduced as an intermediary between the copper interconnection layer and the etching environment. This barrier layer prevents direct contact between copper and etching chemicals, thereby preventing copper elution while maintaining the miniaturized structure. The barrier layer acts as a protective mediator that preserves electrical characteristics during the wet etching process.
Solution Approach 2:
The interconnection structure is designed as a composite material system comprising multiple layers: copper interconnection layer for electrical conductivity, barrier layer for preventing elution, and protective layer for mechanical strength and chemical resistance. This composite structure enables miniaturization while maintaining reliability by combining materials with complementary properties.
2Volume of moving object
If copper interconnection layers are used for miniaturization, then chip size is reduced, but structural integrity deteriorates due to copper elution
Solution Approach 1:
The barrier layer serves as a protective intermediary that stabilizes the copper interconnection layer against chemical attack during wet etching. By preventing direct exposure to etchants, the barrier layer maintains the structural integrity and compositional stability of the copper layer, enabling safe miniaturization.
Solution Approach 2:
The multi-layer composite structure provides enhanced structural integrity through the synergistic combination of materials. The barrier layer and protective layer form a stable outer shell that protects the copper core, preventing elution and maintaining structural integrity even in miniaturized configurations.
3Ease of manufacture
If conventional manufacturing methods are used, then production process is simple, but electrical characteristics deteriorate due to copper elution
Solution Approach 1:
The manufacturing process is segmented into distinct stages: copper layer formation, barrier layer deposition, and protective layer application. This segmentation allows each layer to be optimized independently while maintaining overall process simplicity. The barrier and protective layers are deposited using standard semiconductor fabrication techniques, ensuring ease of manufacture.
Solution Approach 2:
The composite interconnection structure is integrated into the existing manufacturing workflow using established deposition and etching processes. The additional barrier and protective layers are compatible with conventional semiconductor fabrication equipment and procedures, maintaining ease of manufacture while significantly improving electrical characteristics.
Data Source
AI summary
A semiconductor device includes a substrate, plugs, and interconnections. The plugs include a first plug and a second plug that are disposed above the substrate and extend in a first direction that crosses an upper surface of the substrate, and a third plug disposed above and electrically connected to the second plug and extending in the first direction. The interconnections include a first interconnection disposed above and electrically connected to the first plug, a second interconnection disposed below and electrically connected to the first plug, and a third interconnection disposed below and electrically connected to the second plug. The first interconnection contains copper. The third plug contains tungsten. An upper end of the second plug is different in level from an upper end of the first plug and a lower end of the second plug is same in level as a lower end of the first plug.