Sidewall-Integrated Barrier Layer for Narrow Interconnect Recesses
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the difficulty in forming interconnect structures within reduced-sized recesses, which leads to poor sidewall adhesion, void formation, increased contact resistance, and reduced device performance due to the limitations of existing barrier layers that can reduce the recess width and affect the filling performance.
Innovation Solution
A plasma-based deposition method is used to form a barrier layer by diffusing silicon in the sidewalls, creating a silicon-rich surface that reacts with a precursor to form a titanium silicon oxide or titanium silicon nitride barrier layer, which is integrated into the sidewalls rather than grown on top, minimizing cross-sectional width reduction and enhancing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional barrier layer is formed in reduced-sized recesses, then adhesion is improved, but the recess width is reduced and filling performance deteriorates
Solution Approach 1:
The barrier layer is formed with different thicknesses at different locations within the recess. The plasma-based deposition creates a gradient where the barrier layer is thicker at the sidewalls (improving adhesion) and thinner or absent at the bottom (preserving filling performance). This spatial variation in barrier layer quality resolves the contradiction between needing adhesion at sidewalls and maintaining filling capability at the bottom.
Solution Approach 2:
The barrier layer formation transitions from a two-dimensional planar deposition to a three-dimensional conformal deposition that follows the recess geometry. The plasma-based process deposits material that conforms to the sidewall surface, creating a barrier layer that is integrated into the recess structure rather than simply covering it, thus maintaining recess width while providing adhesion.
2Strength
If a barrier layer is formed to promote adhesion, then sidewall adhesion is improved, but contact resistance increases
Solution Approach 1:
The barrier layer is selectively positioned thicker at the sidewalls where adhesion is needed and thinner or removed at the bottom where low contact resistance is critical. This local differentiation allows the system to achieve both good adhesion and low contact resistance by optimizing the barrier layer thickness at different locations.
3Strength
If a barrier layer is grown on top of sidewalls, then adhesion is improved, but cross-sectional width reduction increases
Solution Approach 1:
Instead of growing the barrier layer outward from the sidewall surface (which would reduce the effective recess width), the plasma-based deposition process forms the barrier layer by diffusing silicon from the sidewall bulk to the surface and reacting with precursor in place. This in-situ formation approach integrates the barrier layer into the existing sidewall structure rather than adding external material that would encroach on the recess width.
Solution Approach 2:
The sidewalls provide their own silicon material through diffusion to form the barrier layer, eliminating the need for external barrier layer deposition that would consume additional space. The sidewalls essentially manufacture their own barrier layer from their constituent materials, avoiding the width reduction problem associated with conventional barrier layer deposition.
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 approach reduces roughness, contact resistance, and defects, while improving device performance and yield by promoting better adhesion and filling performance of the interconnect structures within the reduced-sized recesses.
Implementation Method 1
A plasma is used to cause a diffusion of silicon (Si) in the sidewalls toward the surface of the sidewalls
Implementation Method 2
The precursor reacts with the silicon-rich surface to form the barrier layer
Implementation Method 3
The barrier layer is formed in the portion of the thickness of the sidewalls by a plasma-based deposition operation
Data Source
AI summary
A barrier layer is formed in a portion of a thickness of sidewalls in a recess prior to formation of an interconnect structure in the recess. The barrier layer is formed in the portion of the thickness of the sidewalls by a plasma-based deposition operation, in which a precursor reacts with a silicon-rich surface to form the barrier layer. The barrier layer is formed in the portion of the thickness of the sidewalls in that the precursor consumes a portion of the silicon-rich surface of the sidewalls as a result of the plasma treatment. This enables the barrier layer to be formed in a manner in which the cross-sectional width reduction in the recess from the barrier layer is minimized while enabling the barrier layer to be used to promote adhesion in the recess.