FinFET Source/Drain Supportive Layers for Strain Transfer

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Solution Overview

Problem

As semiconductor technology advances to nanometer process nodes, FinFET devices face challenges in achieving uniformity and strain transfer due to the increasing complexity of source/drain formation, leading to issues with channel control and electrical performance.

Innovation Solution

The formation of supportive layers within the source/drains of FinFET devices, comprising different materials and dopant concentrations, helps enhance epitaxial growth, reduce lattice-mismatch, and improve strain transfer to the channel, achieved through a multi-layered structure with specific thickness and composition profiles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multi-layered supportive layers are formed in source/drain regions, then epitaxial growth and strain transfer are enhanced, but device complexity and fabrication process complexity increase

Engineering Contradiction:

Improveepitaxial growth uniformity and strain transferVSAvoidsource/drain structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The source/drain region is divided into multiple layers including a first supportive layer, a second supportive layer, and an intermediate layer. Each layer has different material compositions and thicknesses to perform specific functions: the first supportive layer enhances epitaxial growth, the second supportive layer provides strain transfer, and the intermediate layer facilitates interface between them. This segmentation allows optimization of each layer's properties independently to achieve overall performance improvement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The supportive layers utilize composite material structures where the first supportive layer and second supportive layer are made of different materials with distinct properties. The intermediate layer is formed between these two supportive layers, creating a composite structure that combines the advantages of different materials to simultaneously achieve enhanced epitaxial growth and strain transfer while managing lattice mismatch.

Inventive Principle:

Principle #40Composite materials

2Reliability

If supportive layers with different materials and dopant concentrations are used, then strain transfer to channel is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvestrain transfer efficiencyVSAvoidlayer thickness and composition control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Each supportive layer is designed with specific local properties: the first supportive layer has particular material composition and dopant concentration optimized for epitaxial growth enhancement, while the second supportive layer has different composition and doping optimized for strain transfer. The intermediate layer has properties specifically tailored for interface compatibility. This local quality differentiation allows each region to perform its specific function optimally.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention utilizes parameter changes in material composition, dopant concentration, and layer thickness to achieve different functional outcomes. By varying these parameters across different layers, the structure achieves enhanced epitaxial growth and strain transfer. The method includes controlling thickness ratios and composition gradients to optimize performance while managing manufacturing complexity.

Inventive Principle:

Principle #35Parameter changes

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 results in improved uniformity and electrical performance of FinFET devices by enhancing epitaxial growth and strain transfer, leading to better DC/AC performance and reduced lattice dislocations.

Implementation Method 1

enhance epitaxial growth

Methodology Applied

Scientific EffectEpitaxial growth: Epitaxy

Implementation Method 2

reduce lattice-mismatch

Methodology Applied

Scientific EffectLattice-mismatch reduction:

Implementation Method 3

improve strain transfer to the channel

Methodology Applied

Scientific EffectStrain transfer:

Data Source

PatentUS11855142B2Supportive layer in source/drains of FinFET devices

Publication Date: 2023.12.26 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An embodiment is a semiconductor structure. The semiconductor structure includes a fin on a substrate. A gate structure is over the fin. A source/drain is in the fin proximate the gate structure. The source/drain includes a bottom layer, a supportive layer over the bottom layer, and a top layer over the supportive layer. The supportive layer has a different property than the bottom layer and the top layer, such as a different material, a different natural lattice constant, a different dopant concentration, and/or a different alloy percent content.