FinFET Epitaxy Structure With Dual-Doped Source/Drain Cladding
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Solution Overview
Problem
The scaling down of semiconductor integrated circuit (IC) devices to achieve increased performance and reduced geometry poses challenges in manufacturing, particularly in the formation of multi-gate transistors like finFET devices, where precise control over doping concentrations and epitaxial growth is required to prevent unwanted lateral expansion and ensure adequate junction overlap for optimal channel resistance and performance.
Innovation Solution
The solution involves a method of forming bar-shaped doped source/drain regions with a low phosphorus doping concentration epitaxially grown in recesses, followed by a higher phosphorus doping concentration epitaxial layer on top and sides, using silicon-containing materials and specific doping processes to control dopant concentration and prevent lateral expansion, while ensuring sufficient channel overlap and reducing channel resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single uniform phosphorus doping concentration is used in source/drain regions, then the manufacturing process is simpler, but lateral expansion occurs and junction overlap is insufficient
Solution Approach 1:
The patent applies local quality by implementing a dual-layer epitaxial structure where the first epitaxial layer has a first phosphorus doping concentration and the second epitaxial layer has a second phosphorus doping concentration different from the first. This creates spatially varying doping concentrations within the source/drain regions, allowing precise control over lateral expansion while maintaining manufacturing feasibility through sequential deposition processes.
2Manufacturing precision
If higher phosphorus doping concentration is used throughout, then junction overlap improves, but lateral expansion increases
Solution Approach 1:
The patent resolves this contradiction by assigning different phosphorus doping concentrations to different spatial locations within the source/drain regions. The first epitaxial layer with its specific phosphorus concentration provides foundational doping, while the second epitaxial layer with a different phosphorus concentration is strategically positioned to control lateral expansion. This spatial differentiation allows the structure to achieve adequate junction overlap without excessive lateral expansion that would result from uniform high doping throughout.
3Productivity
If device feature size is scaled down, then production efficiency increases and costs decrease, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the source/drain regions into distinct epitaxial layers with different phosphorus doping concentrations. The first epitaxial layer and second epitaxial layer are formed as separate structural units with controlled thicknesses and doping profiles. This segmentation enables precise control over electrical properties and physical dimensions at scaled feature sizes, managing manufacturing complexity through modular layer construction while maintaining high production efficiency.
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 effectively prevents unwanted merging of adjacent epitaxy structures, improves channel electron mobility, and lowers channel resistance, thereby enhancing the performance and reliability of finFET devices.
Implementation Method 1
a first doped source/drain region extended away from the substrate, and a second doped source/drain region disposed on top and side surfaces of the first doped source/drain region
Data Source
AI summary
A device includes a gate structure extending over a semiconductor channel region, and source/drain epitaxial structures at opposite sides of the gate structure. Each of the source/drain epitaxial structures includes a bar-shaped epitaxial region and a cladding epitaxial layer cladding on the bar-shaped epitaxial region, the cladding epitaxial layer having a dopant concentration higher than a dopant concentration of the bar-shaped epitaxial region.