Wavy Epitaxial Source/Drain Structure for Lower Contact Resistance
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Solution Overview
Problem
Existing multigate devices face challenges in scaling down IC feature sizes and achieving denser packing due to limitations in epitaxial source/drain structures, which affect contact resistance and strain distribution in channel regions.
Innovation Solution
The formation of wavy-shaped epitaxial source/drain structures through controlled epitaxial growth, optimizing parameters such as deposition time, temperature, and precursor concentration to enhance contact area and strain distribution, while minimizing etching impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional epitaxial source/drain structures are used for scaling, then manufacturing process simplicity is maintained, but contact resistance increases and strain distribution deteriorates
Solution Approach 1:
The patent applies curvature by forming wavy-shaped epitaxial source/drain structures instead of conventional planar structures. The wavy shape increases the contact area between the source/drain region and the channel, thereby reducing contact resistance and improving strain distribution throughout the channel region while maintaining a manufacturable epitaxial growth process
Solution Approach 2:
The patent implements local quality by creating regions of varying epitaxial layer thickness within the source/drain structure. The wavy configuration provides localized thickness variations that optimize both contact area at the interface and strain distribution in different channel regions, allowing simultaneous improvement of multiple performance parameters
2Productivity
If aggressive scaling is pursued, then IC feature size decreases and packing density increases, but epitaxial source/drain structure performance deteriorates
Solution Approach 1:
The wavy-shaped epitaxial source/drain structures provide increased surface area and contact area without proportionally increasing the lateral footprint. This allows aggressive scaling and denser packing while maintaining adequate contact area and strain distribution for reliable device operation at smaller feature sizes
3Ease of manufacture
If etching is used to form source/drain recesses, then epitaxial structure formation is enabled, but etching-induced damage increases
Solution Approach 1:
The patent optimizes etching parameters including depth, width, and profile angle of the source/drain recesses to minimize damage while enabling subsequent epitaxial growth. By carefully controlling these parameters, the process enables formation of the wavy-shaped epitaxial structures with reduced etching-induced damage to the semiconductor crystal lattice
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 wavy-shaped epitaxial source/drain structures improve contact resistance and strain distribution, maintaining device performance and reducing etching-induced damage, thereby supporting advanced IC technology nodes.
Implementation Method 1
epitaxial source/drain structures are needed for facilitating smaller IC feature sizes
Data Source
AI summary
Wavy-shaped epitaxial source/drain structures for multigate devices and methods of fabrication thereof are disclosed herein. An exemplary device includes a first fin and a second fin extending lengthwise along a first direction. The first fin and the second fin each have a non-recessed portion and a recessed portion. A gate extends lengthwise along a second direction that is different than the first direction. The gate wraps the non-recessed portion of the first fin and the non-recessed portion of the second fin. A merged epitaxial source/drain is on the recessed portion of the first fin and the recessed portion of the second fin. A source/drain contact is on the merged epitaxial source/drain. The source/drain contact and the merged epitaxial source/drain have a V-shaped interface therebetween. The source/drain contact extends below tops of the non-recessed portions of the first fin and the second fin.