Backside ILD Air Gaps for Lower RC Delay in GAA Transistors
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Solution Overview
Problem
In the semiconductor industry, as devices transition to nanometer technology process nodes, challenges arise in achieving higher device density and performance due to issues like short-channel effects and increased resistance-capacitance (RC) time delay in gate-all-around (GAA) transistors, particularly with the use of backside metal vias which degrade device performance.
Innovation Solution
The implementation of a backside interlayer dielectric (ILD) layer with air gaps around backside metal vias reduces capacitive coupling by utilizing air's low dielectric constant, thereby improving reliability and mitigating RC time delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If backside metal vias are used in GAA transistors, then device density and integration are improved, but RC time delay and capacitive coupling increase, degrading device performance
Solution Approach 1:
An air gap is introduced as an intermediary layer between adjacent backside metal vias. This air gap acts as a mediator that reduces capacitive coupling between the vias by providing a low-dielectric-constant region, thereby reducing RC time delay and improving device performance while maintaining the high device density enabled by backside vias
Solution Approach 2:
The air gap structure creates a porous or void region within the dielectric layer surrounding the backside metal vias. This porous structure filled with air (having a dielectric constant of approximately 1) reduces the overall capacitive coupling between adjacent vias, addressing the performance degradation issue while preserving the benefits of backside via integration
2Ease of manufacture
If conventional dielectric materials are used in backside ILD layer, then manufacturing simplicity is maintained, but capacitive coupling between adjacent vias increases, causing RC time delay
Solution Approach 1:
Instead of using a uniform dielectric material throughout the backside ILD layer, the invention introduces localized air gaps in specific regions between adjacent backside metal vias. This local modification creates regions of low dielectric constant where needed to reduce capacitive coupling and RC time delay, while maintaining conventional dielectric materials in other areas, thus balancing manufacturing simplicity with performance improvement
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 introduction of air gaps in the backside ILD layer enhances electrostatic control and reduces leakage currents, improving the performance and reliability of GAA transistors by minimizing capacitive coupling between adjacent vias.
Implementation Method 1
reduces capacitive coupling by utilizing air's low dielectric constant
Data Source
AI summary
An integrated circuit (IC) structure includes a gate structure, a source epitaxial structure, a drain epitaxial structure, a front-side interconnection structure, a backside dielectric layer, and a backside via. The source epitaxial structure and the drain epitaxial structure are respectively on opposite sides of the gate structure. The front-side interconnection structure is on a front-side of the source epitaxial structure and a front-side of the drain epitaxial structure. The backside dielectric layer is on a backside of the source epitaxial structure and a backside of the drain epitaxial structure and has an air gap therein. The backside via extends through the backside dielectric layer to a first one of the source epitaxial structure and the drain epitaxial structure.