Dummy Fin Profile for FinFET Source/Drain Separation

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Solution Overview

Problem

As semiconductor devices undergo miniaturization, the proximity of dummy fins to channel regions in FinFETs poses challenges in device yield due to potential source/drain merging during epitaxial growth, necessitating improved dummy fin profiles to enhance spacing and process window for gate stack gap filling.

Innovation Solution

Forming a film on the sidewalls of the dummy fin and etching it to create a profile where the middle portion is narrower than the bottom portion, increasing the spacing between the dummy fin and channel regions, and using a combination of films with different materials and etch selectivities to stabilize the dummy fin structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If dummy fins are formed close to channel regions to maintain compact device layout, then device integration density is improved, but source/drain merging occurs during epitaxial growth reducing device yield

Engineering Contradiction:

Improvedevice integration densityVSAvoiddevice yield

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The dummy fin is given a non-uniform width profile where the middle portion is narrower than the top and bottom portions. This local variation in geometry creates increased spacing between the dummy fin and adjacent channel regions at the middle section, preventing source/drain merging during epitaxial growth while maintaining compact overall device layout for high integration density.

Inventive Principle:

Principle #3Local quality

2Reliability

If dummy fin width is reduced uniformly to increase spacing from channel regions, then source/drain merging is prevented, but dummy fin structural stability deteriorates during subsequent processing

Engineering Contradiction:

Improvespacing between dummy fin and channel regionsVSAvoiddummy fin structural stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

Instead of uniform width reduction, the dummy fin employs a non-uniform profile with a narrower middle portion and wider top/bottom portions. The wider top and bottom sections provide structural support and stability during processing, while the narrower middle section ensures adequate spacing from channel regions to prevent source/drain merging.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The solution transitions from considering only the horizontal width dimension to incorporating the vertical dimension by creating a tapered or stepped profile. This multi-dimensional approach allows the dummy fin to have varying widths at different heights, simultaneously achieving spacing requirements and structural stability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If dummy fin profile is modified to prevent source/drain merging, then device yield is improved, but manufacturing process complexity increases

Engineering Contradiction:

Improvedevice yieldVSAvoiddummy fin profile complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The non-uniform width profile of the dummy fin is formed during the initial fin formation process using standard lithography and etching techniques. By preparing the dummy fin with the appropriate profile beforehand, the patent avoids the need for additional complex processing steps later, maintaining manufacturing simplicity while achieving the desired spacing to prevent source/drain merging.

Inventive Principle:

Principle #10Preliminary action

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 improves device yield by preventing unintended source/drain merging and enlarging the process window for gate stack gap filling, reducing manufacturing defects and enhancing the stability of the dummy fin during subsequent processing steps.

Implementation Method 1

forming a film on the sidewalls of the dummy fin

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

forming a film on the sidewalls of the dummy fin

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 3

etching it to create a profile where the middle portion is narrower than the bottom portion

Methodology Applied

Scientific EffectChemical Etching:

Data Source

PatentUS12142609B2Dummy fin between first and second semiconductor fins

Publication Date: 2024.11.12 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An embodiment device includes a first source/drain region over a semiconductor substrate and a dummy fin adjacent the first source/drain region. The dummy fin comprising: a first portion comprising a first film and a second portion over the first portion, wherein the second portion comprises: a second film; and a third film. The third film is between the first film and the second film, and the third film is made of a different material than the first film and the second film. A width of the second portion is less than a width of the first portion. The device further comprises a gate stack along sidewalls of the dummy fin.