Interconnect Barrier Layer Structure for Blocking Pad Metal Diffusion
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Solution Overview
Problem
In semiconductor manufacturing, metal diffusion through multiple barrier layers poses challenges, affecting the performance and reliability of interconnect structures, particularly in preventing metal elements from conductive lines from reaching the pad layer.
Innovation Solution
A multi-layer barrier structure comprising nano-crystalline, amorphous, and poly-crystalline tantalum or titanium nitride layers is conformally deposited to prevent metal diffusion, with specific thickness ratios and phases aligning threading dislocation defects to block metal passage effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple barrier layers are used to prevent metal diffusion, then the reliability of the semiconductor structure is improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The patent employs a composite barrier structure consisting of multiple layers with different materials (e.g., titanium nitride, tantalum nitride, tungsten silicide) and crystalline phases (nano-crystalline, amorphous, poly-crystalline). Each layer contributes different properties to the overall barrier system, creating a synergistic effect that enhances metal diffusion prevention while managing process complexity through systematic material selection.
Solution Approach 2:
The patent applies different material compositions and crystalline phases to specific positions within the barrier structure. For example, nano-crystalline layers are positioned at interfaces where metal diffusion is most problematic, while amorphous layers provide continuous coverage. This localized optimization allows effective diffusion blocking without requiring uniform complexity throughout the entire structure.
2Reliability
If the barrier layer thickness is increased to block metal diffusion, then the reliability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent divides the barrier function into multiple discrete layers rather than using a single thick layer. Each layer has an optimized thickness (e.g., 5-20 nm per layer) that is easier to control with standard deposition processes. The cumulative thickness achieves the required diffusion blocking while individual layer thicknesses remain within manufacturable tolerances.
Solution Approach 2:
The patent utilizes changes in crystalline phase (nano-crystalline, amorphous, poly-crystalline) and material composition to enhance barrier effectiveness at reduced thicknesses. These parameter changes alter the diffusion pathways and energy barriers, allowing thinner layers to achieve the same or better protection than thicker conventional layers, thereby reducing manufacturing precision demands.
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 configuration significantly reduces the failure rate of semiconductor structures by effectively blocking metal diffusion to the pad layer, ensuring enhanced electrical performance and reliability.
Implementation Method 1
A multi-layer barrier structure comprising nano-crystalline, amorphous, and poly-crystalline tantalum or titanium nitride layers is conformally deposited to prevent metal diffusion
Implementation Method 2
with specific thickness ratios and phases aligning threading dislocation defects to block metal passage effectively
Data Source
AI summary
A semiconductor structure includes a conductive line, a pad layer, and a barrier layer. The conductive line is embedded in a multi-level interconnect structure. The pad layer is over the conductive line. The barrier layer is between the conductive line and the pad layer. The pad layer is electrically connected to the conductive line through the barrier layer, and the barrier layer includes a first poly-crystalline layer and a second poly-crystalline layer. A boundary is between the first poly-crystalline layer and the second poly-crystalline layer.