Air Gap Isolation in FinFET Source-Drain Regions
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Solution Overview
Problem
As semiconductor devices continue to shrink in feature size, they face challenges such as increased parasitic capacitance, which affects performance, particularly at higher frequencies, due to the integration density improvements in the semiconductor industry.
Innovation Solution
The formation of air gaps between epitaxial source/drain regions and isolation regions in FinFET devices using dielectric fins, which reduces parasitic capacitance by using air instead of dielectric materials, thereby improving device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dielectric fins are formed between semiconductor fins to improve isolation, then isolation quality is improved, but parasitic capacitance increases
Solution Approach 1:
The patent changes the material parameter of the fin structures by forming epitaxial source/drain regions with different semiconductor compositions (e.g., SiGe) in the dielectric fins adjacent to the semiconductor fins. This compositional parameter change modifies the electrical properties at the interface, reducing parasitic capacitance while maintaining the isolation function of the dielectric fin structure.
Solution Approach 2:
The patent employs composite material structures by combining different semiconductor materials (silicon, SiGe) with dielectric materials in a multi-layer fin configuration. The epitaxial source/drain regions use composite material composition gradients to optimize both isolation performance and electrical characteristics, reducing parasitic capacitance between adjacent fins.
2Productivity
If feature size is reduced to increase integration density, then integration density is improved, but parasitic capacitance increases
Solution Approach 1:
The patent applies local quality modification by implementing selective epitaxial growth of source/drain regions with optimized material composition specifically at the interfaces between adjacent fins. This localized material optimization reduces parasitic capacitance at critical interfaces while maintaining high integration density through continued miniaturization of the overall device structure.
Solution Approach 2:
The patent changes physical parameters of the semiconductor materials used in epitaxial source/drain regions, such as composition ratios and crystalline structure, to reduce parasitic capacitance effects that become more pronounced as feature sizes are reduced for higher 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 reduces parasitic capacitance, enhancing the performance of FinFET devices by minimizing noise and improving signal response at higher frequencies.
Implementation Method 1
performing an epitaxy process to form a epitaxial source/drain region in the first recess, wherein performing the epitaxy process forms an air gap between the epitaxial source/drain region and the first isolation region
Data Source
AI summary
A semiconductor device includes a first semiconductor fin extending from a substrate, a first dielectric fin extending from the substrate adjacent a first side of the first semiconductor fin and a second dielectric fin extending from the substrate adjacent a second side of the first semiconductor fin, a first gate stack over and along sidewalls of the first semiconductor fin, the first dielectric fin, and the second dielectric fin, a first epitaxial source/drain region in the first semiconductor fin and extending from the first dielectric fin to the second dielectric fin, and an air gap between the first epitaxial source/drain region and the substrate, the air gap extending between the first dielectric fin and the second dielectric fin.