FinFET Dummy Fin Structure With Void for Electrical Isolation
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing pattern loading effects and increasing electrical isolation between FinFETs during manufacturing, which affects the integration density and performance of electronic components.
Innovation Solution
The introduction of a dummy fin with a void between active fins in FinFETs, which helps reduce pattern loading effects and enhances electrical isolation by using a dielectric layer with a higher relative permittivity and a void with low relative permittivity, thereby decreasing parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication processes are used without dummy fins, then manufacturing simplicity is maintained, but pattern loading effects increase and electrical isolation between FinFETs deteriorates
Solution Approach 1:
The patent introduces dummy fins that replicate the geometric structure of active fins without functional semiconductor material. These dummy fins copy the shape, size, and positioning of real fins to provide mechanical support and reduce pattern loading effects during fabrication, while being electrically isolated by dielectric material to prevent interference with active devices.
Solution Approach 2:
The patent employs dielectric material as an intermediary substance positioned between dummy fins and active fins. This dielectric layer acts as a mediator that provides electrical isolation while allowing the dummy fins to maintain their structural function. The intermediary dielectric material enables the dummy fins to contribute to mechanical stability without creating electrical interference.
2Manufacturing precision
If dummy fins are added to reduce pattern loading effects, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The dummy fins are designed as geometric copies of active fins, matching their dimensions and spacing. This copying approach allows the dummy fins to effectively simulate the mechanical and optical loading conditions of real fins during fabrication processes, thereby improving pattern uniformity and manufacturing precision without requiring complex variable structures.
Solution Approach 2:
The patent applies dummy fins selectively in specific regions where pattern loading effects are most problematic, rather than uniformly across the entire substrate. This localized application optimizes manufacturing precision in critical areas while minimizing the overall increase in device complexity and resource consumption.
3Reliability
If dielectric material with higher relative permittivity is used in dummy fins, then electrical isolation improves, but parasitic capacitance increases
Solution Approach 1:
The patent carefully selects and optimizes the relative permittivity parameter of the dielectric material used in dummy fins. By adjusting this parameter, the design achieves sufficient electrical isolation to prevent interference with active FinFETs while maintaining parasitic capacitance at acceptable levels. The dielectric constant is chosen to balance isolation requirements against capacitance generation.
Solution Approach 2:
The dielectric material with specific permittivity properties is applied locally in the regions surrounding dummy fins, rather than uniformly throughout the entire device structure. This localized application ensures that electrical isolation is enhanced precisely where needed near the dummy fins, while minimizing the overall parasitic capacitance impact on the circuit.
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 pattern loading effects and increases electrical isolation between FinFETs, leading to improved integration density and performance by decreasing parasitic capacitance by up to 20%.
Implementation Method 1
using a dielectric layer with a higher relative permittivity and a void with low relative permittivity, thereby decreasing parasitic capacitance
Data Source
AI summary
In an embodiment, a device includes: a first semiconductor strip over a substrate, the first semiconductor strip including a first channel region; a second semiconductor strip over the substrate, the second semiconductor strip including a second channel region; a dielectric strip disposed between the first semiconductor strip and the second semiconductor strip, a width of the dielectric strip decreasing along a first direction extending away from the substrate, the dielectric strip including a void; and a gate structure extending along the first channel region, along the second channel region, and along a top surface and sidewalls of the dielectric strip.