Dummy Fin FinFET Structure for Consistent Fin Width Control

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Solution Overview

Problem

Existing FinFET devices face challenges in maintaining consistent fin width and size during fabrication, leading to variations in performance due to loading effects and fin bending, which affects the device's overall efficiency and reliability.

Innovation Solution

The method involves forming first and second fin structures with a tapered width, using a liner layer to protect the fin structures, and performing a fin cut last process where the patterned photoresist layer with regular spaces is used to ensure consistent fin width and size, followed by removing a portion of the second fin structures after annealing to maintain the space between fin structures, thereby reducing variations and improving performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional FinFET fabrication is used, then device density and performance are improved, but fin width variation and fin bending occur leading to performance inconsistency

Engineering Contradiction:

Improvedevice densityVSAvoidfin width consistency

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The method forms dummy fin structures in advance before the main fin structures, and performs annealing treatment beforehand to establish a controlled stress environment. This preliminary action prevents fin bending in subsequent fabrication steps by pre-compensating for stress effects, thereby maintaining fin width consistency while enabling high device density.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the physical and chemical parameters of the fin structures through controlled annealing processes. By adjusting temperature, time, and atmosphere parameters during annealing, the stress state of the fins is modified to prevent bending, thus maintaining manufacturing precision while supporting high-density device fabrication.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If loading effects are reduced, then fin width consistency is improved, but additional process steps are required increasing fabrication complexity

Engineering Contradiction:

Improvefin width consistencyVSAvoidfabrication process steps

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The method combines the formation of dummy fin structures with the main fin structure fabrication process. The dummy fins are formed using the same lithography and etching steps as the functional fins, merging multiple purposes into unified process steps. This approach reduces fin width variation without significantly increasing fabrication complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The dummy fin structures serve multiple functions: they provide stress compensation to prevent fin bending, act as placeholders for subsequent processing steps, and maintain pattern alignment throughout fabrication. This multi-functionality allows the additional structures to be justified without proportionally increasing process complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 ensures consistent fin width and size, reducing fin bending and maintaining the space between fin structures, resulting in improved performance and reliability of the FinFET device structure.

Implementation Method 1

using a liner layer to protect the fin structures

Methodology Applied

Scientific EffectPhysical barrier protection:

Implementation Method 2

performing a fin cut last process where the patterned photoresist layer with regular spaces is used to ensure consistent fin width and size, followed by removing a portion of the second fin structures after annealing

Methodology Applied

Scientific EffectAnnealing: Annealing

Data Source

PatentUS12020988B2Fin field effect transistor (FinFET) device structure with dummy fin structure

Publication Date: 2024.06.25 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A fin field effect transistor (FinFET) device structure with dummy fin structures and method for forming the same are provided. The FinFET device structure includes an isolation structure over a substrate, and a first fin structure extended above the isolation structure. The fin field effect transistor (FinFET) device structure includes a second fin structure adjacent to the first fin structure, and a material layer formed over the fin structure. The material layer and the isolation structure are made of different materials, the material layer has a top surface with a top width and a bottom surface with a bottom width, and the bottom width is greater than the top width.