Source/Drain Air-Gap Spacer for Lower Parasitic Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor technologies face challenges in reducing parasitic capacitance in three-dimensional nanostructure field-effect transistors (FETs) without compromising other design requirements, such as resistance, as the scaling down of ICs increases complexity and parasitic capacitance affects device performance.
Innovation Solution
A method for forming a source/drain spacer with an air gap to reduce parasitic capacitance, involving the formation of a semiconductor fin with a dielectric fin and epitaxial S/D feature, where an air gap is created within the spacer layer to decrease the dielectric constant and cross-sectional area of the S/D feature, thereby reducing parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If separation distances between active device regions are reduced to meet smaller technology nodes, then device density increases, but parasitic capacitance increases leading to lower device speed
Solution Approach 1:
The spacer structure incorporates an air gap (porous region) within the dielectric material, creating a composite structure with lower effective dielectric constant. This reduces parasitic capacitance between adjacent device regions while maintaining the required separation distance, thereby preserving device speed performance despite increased device density
Solution Approach 2:
The spacer is formed as a composite structure combining dielectric material with an air gap region. This composite approach allows optimization of the effective dielectric constant to reduce parasitic capacitance while maintaining mechanical integrity and electrical isolation functions
2Object-generated harmful factors
If spacer cross-sectional area is reduced to reduce parasitic capacitance, then parasitic capacitance decreases, but resistance increases
Solution Approach 1:
The air gap is positioned strategically within the spacer structure to locally reduce dielectric constant where it most effectively reduces parasitic capacitance. The spacer cross-sectional area is optimized to maintain sufficient conductive path while the air gap provides capacitance reduction, achieving both goals simultaneously
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 method effectively reduces parasitic capacitance while maintaining reasonable resistance and allowing for improved device performance by creating an air gap within the S/D spacer, enhancing the scaling capability and control over short-channel effects in nanostructure FETs.
Implementation Method 1
an air gap is created within the spacer layer to decrease the dielectric constant and cross-sectional area of the S/D feature, thereby reducing parasitic capacitance
Data Source
AI summary
A semiconductor structure includes a semiconductor fin protruding from a substrate, a dielectric fin disposed adjacent and substantially parallel to the semiconductor fin, an epitaxial source/drain (S/D) feature disposed in the semiconductor fin, a dielectric layer disposed between a sidewall of the epitaxial S/D feature and a sidewall of the dielectric fin, and an air gap disposed in the dielectric layer.