Gradient ALD Barrier Layer for Copper Diffusion and Plasma Damage
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Solution Overview
Problem
As feature sizes in semiconductor manufacturing continue to shrink, it becomes increasingly challenging to form high-quality barrier layers in narrow openings with high aspect-ratios, leading to issues such as low density films that fail to prevent copper diffusion into underlying dielectric layers and plasma-induced damage.
Innovation Solution
A gradient atomic layer deposition (ALD) process is employed to form a diffusion barrier layer with varying carbon concentrations, where upper sublayers have higher carbon concentrations to protect the underlying dielectric layer from plasma damage, followed by a plasma treatment to reduce carbon content and enhance layer density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ALD process is used to form barrier layer, then the barrier layer can be formed in narrow openings, but the film density is low and fails to prevent copper diffusion
Solution Approach 1:
The patent applies local quality by creating a gradient carbon concentration profile within the barrier layer, where the carbon concentration varies through the thickness of the layer. This gradient structure provides different local properties: higher carbon concentration near the dielectric interface for plasma protection and lower carbon concentration toward the copper interface for diffusion barrier functionality, thereby resolving the contradiction between forming the layer in narrow openings and preventing copper diffusion.
Solution Approach 2:
The patent employs parameter changes by systematically varying the carbon concentration parameter through the barrier layer thickness using gradient ALD processes. By controlling precursor flow rates and deposition conditions to create a continuous carbon concentration gradient, the film achieves both adequate density for copper diffusion prevention and appropriate plasma resistance, thus resolving the reliability issue.
2Object-affected harmful factors
If barrier layer with high carbon concentration is formed to protect from plasma damage, then plasma resistance improves, but copper diffusion prevention capability deteriorates
Solution Approach 1:
The gradient carbon concentration profile implements local quality by assigning different carbon concentrations to different regions of the barrier layer. The region adjacent to the dielectric layer has higher carbon concentration for plasma damage protection, while the region adjacent to the copper layer has lower carbon concentration for effective diffusion barrier performance, thus resolving the contradiction between plasma resistance and copper diffusion prevention.
Solution Approach 2:
The barrier layer is effectively segmented into multiple sub-layers with different carbon concentrations through the gradient ALD process. This segmentation allows the lower carbon concentration region to function as the primary copper diffusion barrier while the higher carbon concentration region provides plasma protection, thereby resolving the functional conflict between the two requirements.
3Productivity
If feature sizes are reduced to increase integration density, then more components can be integrated, but forming high-quality barrier layers in high aspect-ratio openings becomes more challenging
Solution Approach 1:
The gradient ALD process employs parameter changes by dynamically adjusting precursor flow rates and deposition conditions during the deposition sequence to create the carbon concentration gradient. This controlled parameter variation enables the formation of high-quality barrier layers with appropriate density and composition even in high aspect-ratio openings, thereby maintaining manufacturing precision while supporting continued scaling for higher integration density.
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
The approach results in a barrier layer with improved density and uniformity, reducing the risk of copper diffusion and plasma-induced damage, thereby enhancing semiconductor device performance and reliability.
Implementation Method 1
a first atomic layer deposition (ALD) process is performed to form a first barrier layer lining sidewalls of the opening
Implementation Method 2
performing a plasma process to treat the barrier layer
Data Source
AI summary
A method for forming a semiconductor device includes forming a barrier layer over a dielectric layer, a concentration of an impurity in the barrier layer increasing as the barrier layer extends away from the dielectric layer; and performing a plasma process to treat the barrier layer.