FinFET Source/Drain Supportive Layers for Uniform 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 in source/drain regions due to increasing complexity and scale, which affects device performance and reliability.
Innovation Solution
The formation of supportive layers within the source/drain regions of FinFET devices, comprising different materials and dopant concentrations, helps enhance epitaxial growth, reduce lattice-mismatch, and control the shape and uniformity of the source/drain structures, thereby improving strain transfer to the channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If supportive layers are added within source/drain regions to enhance epitaxial growth and control uniformity, then manufacturing precision and strain transfer are improved, but device complexity increases
Solution Approach 1:
The source/drain region is segmented into multiple layers including a first source/drain layer, a second source/drain layer, and an intermediate layer between them. This segmentation allows each layer to be independently controlled and optimized, improving uniformity and strain transfer while managing complexity through modular design
Solution Approach 2:
The intermediate layer is positioned specifically between the first and second source/drain layers to provide localized strain transfer enhancement. This layer has different material properties (e.g., SiGe with specific germanium content) tailored to its specific function of improving hole mobility in the channel region, rather than uniformly modifying the entire structure
2Reliability
If multiple layers with different materials and dopant concentrations are formed, then strain transfer to channel is enhanced, but manufacturing process complexity increases
Solution Approach 1:
The patent employs parameter changes by varying the germanium content in SiGe layers (e.g., 5-50% Ge in first source/drain layer, 10-60% Ge in intermediate layer) and dopant concentrations across different layers. These parameter variations enable precise control of strain characteristics and carrier mobility, improving reliability while the systematic approach to parameter selection manages process complexity
Solution Approach 2:
The structure uses composite materials consisting of multiple SiGe layers with different germanium compositions and silicon-germanium-silicon combinations. These composite structures provide tailored strain profiles and electrical properties, enhancing strain transfer effectiveness through material composition optimization rather than relying on complex processing steps
3Productivity
If the aspect ratio of fins is increased to achieve higher device density, then productivity is improved, but manufacturing precision of source/drain regions deteriorates
Solution Approach 1:
By segmenting the source/drain region into multiple thin layers (first source/drain layer, intermediate layer, second source/drain layer), the patent achieves better uniformity control even in high aspect ratio fins. Each layer can be formed with precise thickness control, and their cumulative effect maintains uniformity while enabling higher device density through increased fin aspect ratios
Solution Approach 2:
The patent transitions from a planar source/drain structure to a vertically stacked multi-layer structure. This dimensional change allows uniformity to be controlled through vertical layering rather than lateral expansion, enabling high aspect ratio fins with maintained precision through controlled epitaxial growth in the vertical dimension
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 leads to improved electrical performance and reduced lattice dislocations, resulting in more uniform and effective strain transfer to the channel, enhancing the overall performance and reliability of FinFET devices.
Implementation Method 1
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
Implementation Method 2
The formation of supportive layers within the source/drain regions of FinFET devices, comprising different materials and dopant concentrations, helps enhance epitaxial growth
Implementation Method 3
improving strain transfer to the channel
Data Source
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.