BEOL Wiring Barrier Structure With 2D Sidewalls and Low Resistance
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Solution Overview
Problem
As semiconductor devices continue to downscale, there is a demand for higher integration and lower power consumption, which poses challenges in achieving stable and reliable wiring connections, particularly in the BEOL process where feature sizes are decreasing.
Innovation Solution
The semiconductor device incorporates a unique wiring structure with an upper barrier structure featuring a two-dimensional material for the side walls and a tantalum sulfide barrier film, along with a tantalum nitride liner film, to enhance the reliability and performance of wiring connections by reducing resistance and preventing material diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If feature size is decreased to achieve higher integration, then integration density is improved, but wiring connection reliability deteriorates
Solution Approach 1:
The patent employs a composite barrier structure consisting of a two-dimensional material layer (such as graphene or hBN) combined with a conventional barrier material layer (such as tantalum nitride or tungsten). This composite structure leverages the unique properties of two-dimensional materials - particularly their atomic-level flatness and resistance to diffusion - to maintain wiring connection reliability even as feature sizes decrease and integration density increases.
Solution Approach 2:
The two-dimensional material layer is selectively applied to specific regions where diffusion prevention is most critical, such as at the interfaces between wiring structures and interlayer insulating films. This localized application ensures that the most vulnerable areas against material diffusion receive enhanced protection, thereby maintaining connection reliability in high-density configurations.
2Ease of manufacture
If conventional barrier structures are used in downscaled devices, then manufacturing simplicity is maintained, but material diffusion increases causing connection instability
Solution Approach 1:
The two-dimensional material layer is integrated within the existing multi-layer barrier structure, nesting it between the interlayer insulating film and the conventional barrier material layer. This nested configuration allows the advanced two-dimensional material to be incorporated without completely redesigning the manufacturing process, as it fits within the existing layer stack and can be deposited using modified versions of current deposition techniques.
Solution Approach 2:
The two-dimensional material acts as an intermediary layer between the conventional barrier materials and the wiring structures. This intermediary layer prevents direct contact and potential diffusion between adjacent materials, thereby stabilizing the connection composition without requiring complete replacement of the conventional barrier structure.
3Reliability
If barrier film coverage is extended to all surfaces, then diffusion prevention is improved, but resistance increases due to excessive barrier material
Solution Approach 1:
Instead of applying barrier material to all surfaces, the two-dimensional material layer is selectively applied only to the bottom surface of the upper wiring trench where diffusion is most problematic. The side walls are either left uncovered or receive a different treatment, providing sufficient diffusion prevention at the critical interface without adding excessive barrier material that would increase resistance.
Solution Approach 2:
The barrier structure is segmented into different regions with different material compositions and thicknesses. The two-dimensional material is concentrated at the bottom interface where it provides maximum diffusion prevention, while the side walls have reduced or different barrier coverage, allowing current flow with minimal resistance while still preventing material diffusion at the critical junction.
Data Source
AI summary
A semiconductor device includes a lower wiring structure, an upper interlayer insulating film on the lower wiring structure and including an upper wiring trench and an upper wiring structure in the upper wiring trench. The upper wiring structure includes an upper barrier structure, and an upper filling film on the upper barrier structure. The upper barrier structure includes side wall portions extending along side walls of the upper wiring trench, and a bottom portion extending along a bottom face of the upper wiring trench. The upper barrier structure includes an upper barrier film, and an upper liner film between the upper barrier film and the upper filling film. The side wall portions of the upper barrier structure include a two-dimensional material (2D material), and the bottom face of the upper barrier structure is free of the two-dimensional material.