Dummy Structure at Fin Cut for Mechanical Stability

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Solution Overview

Problem

In the semiconductor industry, particularly in the fabrication of FinFETs, there is a challenge in achieving sufficient electrical isolation, mechanical strength, and reliability of fin structures, especially after the fin-cut process, which can lead to damage to gate structures and loss of Shallow Trench Isolation (STI) during subsequent processing steps.

Innovation Solution

The formation of dummy structures within the fin-cut region, including dummy fin structures and bulk dummy structures, which provide additional mechanical stability and prevent damage to gate structures by filling gaps between fin structures and extending between adjacent fins, thereby enhancing electrical isolation and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fin structures are cut to separate sections, then electrical isolation between sections is improved, but mechanical strength and reliability of the fin structures deteriorate

Engineering Contradiction:

Improveelectrical isolationVSAvoidmechanical strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

A dummy fin structure is introduced as an intermediary element within the fin-cut region. This dummy structure serves as a mechanical support that prevents damage to the gate structure while maintaining electrical isolation between the separated fin sections. The dummy fin acts as a mediator that fills the structural gap created by the cut without compromising the electrical separation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The dummy fin structure is a simplified copy or replica of the actual fin structure. It mimics the geometric and material properties of real fins to provide mechanical support and maintain process compatibility, while being electrically isolated or non-functional to preserve circuit separation. This copying approach allows the dummy structure to fulfill mechanical roles without interfering with electrical functions.

Inventive Principle:

Principle #26Copying

2Adaptability or versatility

If fin structures are cut to separate sections, then circuit design flexibility is improved, but gate structure reliability deteriorates due to damage during subsequent processing

Engineering Contradiction:

Improvecircuit design flexibilityVSAvoidgate structure reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The dummy fin structure provides beforehand cushioning or protection for the gate structure. By placing the dummy fin in advance within the fin-cut region, it prevents mechanical damage to the gate structure during subsequent processing steps such as chemical mechanical polishing (CMP) or etching. This prior protective measure ensures gate reliability while allowing design flexibility.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The dummy fin acts as an intermediary protective element between the fin-cut region and the gate structure. It absorbs mechanical stress and prevents direct damage to the gate during processing, thereby maintaining gate reliability while enabling the fin-cut design for circuit flexibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If fin structures are cut to separate sections, then production efficiency is improved, but STI loss occurs during subsequent processing steps

Engineering Contradiction:

Improveproduction efficiencyVSAvoidSTI loss

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The dummy fin structure serves as an intermediary that prevents STI loss during subsequent processing. By providing mechanical support and maintaining structural integrity in the fin-cut region, it prevents the shallow trench isolation (STI) material from being damaged or lost during CMP or other processing steps, thereby preserving STI quality while maintaining production efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Strength

If dummy structures are added to fin-cut regions, then mechanical stability and gate structure reliability are improved, but device complexity increases

Engineering Contradiction:

Improvemechanical stabilityVSAvoidstructure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The dummy fin structure is a simplified copy of the actual fin, using the same or similar materials and geometry. This copying approach provides mechanical stability without introducing complex new structures. The dummy fin can be formed using the same fabrication processes as real fins, minimizing additional process complexity while achieving the desired mechanical support.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The dummy fin structure uses homogeneous materials and geometry matching the surrounding fin structures. This homogeneity ensures that the dummy fin integrates seamlessly with the existing device architecture, maintaining uniform mechanical properties without introducing structural complexity. The dummy fin can be processed together with real fins using the same materials and techniques.

Inventive Principle:

Principle #33Homogeneity

Data Source

PatentUS11205714B2Dummy structure at fin cut

Publication Date: 2021.12.21 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

In one example, a semiconductor device includes a substrate, a first elongated fin structure disposed on the substrate, and a second elongated fin structure disposed on the substrate. The longitudinal axis of the first elongated fin structure is aligned with a longitudinal axis of the second elongated fin structure. The device further includes a dummy structure extending between the first elongated fin structure and the second elongated fin structure. The dummy structure includes a dielectric material.