FinFET Source Drain Air Gap Insulation Leakage Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional FinFETs suffer from leakage paths between source/drain regions and the substrate, and shallow trench isolation (STI) causes fin-height variations due to etching loading effects, while forming FinFETs on a silicon-on-insulator (SOI) substrate is expensive.
Innovation Solution
Forming air gaps or oxide-containing materials to insulate source/drain regions from the substrate, reducing leakage currents by creating a gap or layer between the fin and the substrate, which can be achieved by oxidizing porous silicon or forming a dielectric layer to isolate the source/drain regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional FinFET structure is used with source/drain regions contacting the substrate, then device fabrication is simpler, but leakage paths exist between source/drain regions and substrate causing increased leakage current
Solution Approach 1:
An air gap is introduced as an intermediary insulating layer between the source/drain regions and the substrate. This air gap acts as a mediator that blocks leakage current paths while maintaining the electrical connection functionality, thereby reducing leakage current without requiring complete structural redesign
Solution Approach 2:
The air gap functions as a thin insulating barrier that provides electrical isolation between the source/drain regions and substrate. This thin film approach effectively blocks leakage paths while minimizing the added structural complexity and maintaining device compactness
2Reliability
If shallow trench isolation (STI) is used to insulate the gate from the substrate, then electrical insulation is improved, but etching loading effects cause fin-height variations
Solution Approach 1:
The air gap provides a simple, effective insulating solution that avoids the complex STI structure. By using a lightweight air-filled space instead of bulky trench isolation structures, the method achieves electrical insulation without the etching loading effects that cause fin-height variations
Solution Approach 2:
The invention changes the insulating mechanism from material-based (STI) to space-based (air gap). This parameter change in the insulation approach eliminates the etching process that causes fin-height variations while maintaining effective electrical insulation between gate and substrate
3Reliability
If FinFETs are formed on silicon-on-insulator (SOI) substrate to reduce leakage, then leakage current is reduced, but manufacturing cost increases significantly
Solution Approach 1:
The air gap provides a low-cost alternative to expensive SOI substrates. By using a simple air-filled space instead of costly pre-fabricated SOI wafers, the invention achieves leakage reduction while maintaining compatibility with standard silicon substrate manufacturing processes
Solution Approach 2:
The invention changes the substrate requirement from expensive SOI to standard silicon by introducing an air gap structure. This parameter change in the substrate-insulation approach maintains leakage reduction benefits while dramatically reducing manufacturing costs and simplifying the fabrication process
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 leakage currents and eliminates fin-height variations, providing improved electrical insulation without the high cost associated with SOI substrates.
Implementation Method 1
forming air gaps or oxide-containing materials to insulate source/drain regions from the substrate, reducing leakage currents by creating a gap or layer between the fin and the substrate, which can be achieved by oxidizing porous silicon
Data Source
AI summary
A Fin field effect transistor includes a fin disposed over a substrate. A gate is disposed over a channel portion of the fin. A source region is disposed at a first end of the fin. A drain region is disposed at a second end of the fin. The source region and the drain region are spaced from the substrate by at least one air gap.