Merged Multi-Facet Source/Drain Structure for FinFET Channel Strain

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Solution Overview

Problem

Existing FinFET devices lack a flexible integration method for forming a strain booster in the channel region, which limits their performance and efficiency.

Innovation Solution

A method for forming a source/drain feature with a merged portion having a flat top surface, which enhances strain effect on the gate channel region and reduces resistance, involves epitaxial growth of SiGe or other semiconductor materials over recesses in the substrate, merging individual plug-type portions into a single feature with a flat top surface, and using a combination of deposition and etching processes to achieve this structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If existing FinFET devices are used with conventional source/drain structures, then the device structure is simple to manufacture, but the strain effect on the channel region is insufficient and resistance is high

Engineering Contradiction:

Improvesource/drain structure fabricationVSAvoidchannel strain boosting and source/drain resistivity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The source/drain structure is divided into multiple discrete plug-type portions formed in separate recesses within the channel region. Each plug-type portion is independently formed through epitaxial growth, allowing for optimized strain distribution and reduced resistance while maintaining manufacturing feasibility through modular fabrication processes

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a conventional planar source/drain structure to a three-dimensional merged structure where multiple plug-type portions are vertically and laterally integrated. This dimensional transformation creates a complex spatial arrangement that enhances strain effect and reduces resistance while maintaining compatibility with existing FinFET fabrication processes

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If multiple plug-type portions are formed in recesses, then the volume of source/drain feature increases enhancing strain effect, but the manufacturing process complexity increases

Engineering Contradiction:

Improvechannel strain boostingVSAvoidsource/drain structure configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple separately formed plug-type portions are merged into a single integrated source/drain feature through epitaxial overgrowth. This merging process combines the strain-enhancing benefits of multiple discrete structures while simplifying the final configuration into a unified feature that is easier to manufacture and integrate into the FinFET device

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Individual plug-type portions are pre-formed in recesses before the final merging step. This preliminary action allows for optimized strain distribution to be established early in the fabrication process, while subsequent merging consolidates the structure into a simpler final configuration that reduces manufacturing complexity

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

The approach enhances channel strain boosting and reduces source/drain resistivity, improving the performance of FinFET devices by increasing the volume of the source/drain feature and ensuring a flat surface for effective strain distribution.

Implementation Method 1

growing a semiconductor layer in each of the source/drain recess and overgrowing the semiconductor layer from each of the source/drain recess to merge to a single structure

Methodology Applied

Scientific EffectEpitaxial growth: Epitaxy

Data Source

PatentUS11901452B2Source/drain structure having multi-facet surface

Publication Date: 2024.02.13 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A fin-like field-effect transistor (FinFET) device is disclosed. The device includes a semiconductor substrate having a source/drain region, a plurality of isolation regions over the semiconductor substrate and a source/drain feature in the source/drain region. The source/drain feature includes a multiple plug-type portions over the substrate and each of plug-type portion is isolated each other by a respective isolation region. The source/drain feature also includes a single upper portion over the isolation regions. Here the single upper portion is merged from the multiple plug-type portions. The single upper portion has a flat top surface facing away from a top surface of the isolation region.