FinFET Epitaxial Source/Drain Layout to Prevent Lateral Merger
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Solution Overview
Problem
As FinFET devices decrease in size, the lateral growth of epitaxial source/drain regions can cause adjacent devices to merge, leading to unwanted shorting due to the inability to control the lateral expansion effectively.
Innovation Solution
The implementation of a fin spacer with varying heights along the sidewalls of the epitaxial source/drain segments, which controls the lateral growth by extending to different heights on outer and inner sidewalls, preventing the merger of adjacent FinFET devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxial source/drain regions are formed in FinFET devices, then device performance is improved, but lateral growth causes adjacent devices to merge leading to shorting
Solution Approach 1:
A mandrel structure is introduced as an intermediary element positioned between adjacent FinFET devices. This mandrel physically separates the epitaxial source/drain regions during formation, preventing lateral growth merger while allowing the epitaxial regions to form correctly on each fin, thus maintaining device performance without causing shorting between adjacent devices
Solution Approach 2:
The harmful lateral growth effect is extracted and isolated by introducing the mandrel structure that specifically targets and prevents the unwanted merger phenomenon. The mandrel removes the harmful interaction between adjacent epitaxial regions while preserving the beneficial electrical properties of each individual FinFET device
2Productivity
If FinFET devices are scaled down in size, then integration density is improved, but control over lateral expansion of epitaxial regions becomes difficult
Solution Approach 1:
The mandrel serves as a precision intermediary structure that provides physical boundaries for epitaxial growth at scaled dimensions. By positioning mandrels between closely spaced fins, the invention enables precise control over lateral expansion even when devices are scaled down to increase integration density, maintaining manufacturing precision despite reduced feature sizes
Solution Approach 2:
The mandrel structure introduces local quality variations by providing differentiated physical constraints at different locations - specifically between adjacent fins where lateral growth control is needed. This localized intervention allows precise control of epitaxial expansion in critical regions while maintaining the scaled-down geometry required for high integration density
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 mitigates the merger of epitaxial source/drain regions between adjacent FinFET devices, improving the reliability and performance of integrated chips by managing the lateral growth of the epitaxial source/drain regions.
Implementation Method 1
forming epitaxial source/drain regions onto the plurality of fins
Data Source
AI summary
The present disclosure relates an integrated chip. The integrated chip may include a semiconductor substrate having sidewalls that define a plurality of fins. A dielectric material is arranged between the plurality of fins and a gate structure is disposed over the dielectric material and around the plurality of fins. Epitaxial source/drain regions are disposed along opposing sides of the gate structure and respectively include a plurality of source/drain segments disposed on the plurality of fins and a doped epitaxial material disposed onto and between the plurality of source/drain segments. A first source/drain segment of the plurality of source/drain segments laterally extends in opposing directions to different distances past opposing sides of an underlying first fin of the plurality of fins.