FinFET Dummy Fin Structure for Isolation and Pattern Loading
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing pattern loading effects and electrical isolation between FinFETs during manufacturing, which affects integration density and performance.
Innovation Solution
The introduction of a dummy fin with a void between active fins, formed to match the height of active fins, helps reduce pattern loading effects and increases electrical isolation by using a dielectric layer with high relative permittivity and a void with low relative permittivity, thereby decreasing parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dummy fin is formed between active fins, then pattern loading effects are reduced and electrical isolation is improved, but device complexity increases due to additional manufacturing steps
Solution Approach 1:
The dummy fin structure is segmented into multiple functional zones: a first portion extending from the substrate to a first height, and a second portion extending from the first height to a second height. This segmentation allows different portions to serve different purposes - the first portion provides structural support and pattern loading reduction, while the second portion enhances electrical isolation without interfering with active device formation.
Solution Approach 2:
The dummy fin acts as an intermediary structure between active fins, providing both mechanical support during manufacturing (reducing pattern loading effects) and electrical isolation (through the dielectric material in the second portion). This intermediary structure resolves the contradiction by mediating between the needs of pattern fidelity and electrical isolation.
2Reliability
If the dummy fin includes a second portion extending above the first portion, then electrical isolation is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
Different portions of the dummy fin are assigned different qualities and functions. The first portion has a height matching the gate structure to provide pattern loading reduction, while the second portion extends higher to provide enhanced electrical isolation. This local differentiation of quality allows each portion to optimize its function without compromising manufacturing precision.
Solution Approach 2:
The dummy fin structure utilizes vertical dimensionality by creating a two-level height structure. The first portion operates at the gate structure height level, while the second portion extends to a higher level for isolation purposes. This dimensional approach allows electrical isolation enhancement without requiring precise control of the entire fin structure at the higher level.
3Productivity
If integration density is increased by reducing minimum feature size, then more components are integrated into a given area, but pattern loading effects and electrical isolation challenges worsen
Solution Approach 1:
The dummy fin is segmented into two functional portions with different heights. The first portion (matching gate height) addresses pattern loading effects, while the second portion (extending higher) addresses electrical isolation. This segmentation allows both concerns to be addressed simultaneously, enabling higher integration density without sacrificing reliability.
Solution Approach 2:
The dummy fin structure combines different materials - semiconductor material for the first portion and dielectric material for the second portion. This composite structure allows the lower portion to provide mechanical support for pattern loading reduction, while the upper dielectric portion provides electrical isolation, thereby supporting 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
This approach enhances the integration density and performance of FinFETs by reducing pattern loading effects and increasing electrical isolation between adjacent transistors, leading to improved manufacturing efficiency and device performance.
Implementation Method 1
using a dielectric layer with high 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.