Strained FinFET Leakage Barrier Layer
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Solution Overview
Problem
FinFETs face challenges in achieving high drive currents with smaller dimensions due to increased leakage current from p-n junctions formed within silicon germanium layers, which degrade short channel characteristics and mobility.
Innovation Solution
A method involving the formation of a leakage barrier layer with a higher bandgap than the semiconductor layers in the source and drain regions, doped to contain the depletion region and reduce leakage current, combined with strained semiconductor layers to enhance mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If silicon germanium layers are used in source and drain regions to enhance carrier mobility, then carrier mobility is improved, but leakage current increases due to p-n junction formation
Solution Approach 1:
An intrinsic semiconductor layer is introduced as an intermediary between the first and second doped semiconductor layers. This intrinsic layer acts as a mediator that prevents direct p-n junction formation between oppositely doped regions, thereby eliminating the associated leakage current while preserving the mobility-enhancing silicon germanium layers.
Solution Approach 2:
The semiconductor structure is segmented into multiple distinct layers: a first doped semiconductor layer, an intrinsic semiconductor layer, and a second doped semiconductor layer. This segmentation separates the mobility-enhancing doped regions from each other, preventing harmful p-n junction interactions while maintaining individual layer functionality.
2Productivity
If device dimensions are reduced to achieve miniaturization, then integration density is improved, but leakage current increases and drive current capability deteriorates
Solution Approach 1:
The intrinsic semiconductor layer serves as a mediator that suppresses leakage current in miniaturized devices by preventing p-n junction formation. This allows continued scaling to higher integration densities without the leakage current that would otherwise limit further miniaturization.
3Ease of manufacture
If p-n junctions are formed in source and drain regions, then doping is simplified, but short channel characteristics deteriorate due to increased leakage
Solution Approach 1:
The structure is segmented into separate doped regions divided by an intrinsic layer, preventing p-n junction formation. This segmentation maintains reliable short channel characteristics while allowing independent doping of source and drain regions without the harmful interactions that would degrade device performance.
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 current and maintains shallow source/drain junctions, preserving short channel characteristics and enhancing carrier mobility, thereby improving the performance of FinFETs.
Implementation Method 1
A leakage barrier layer is formed on the first semiconductor layer. The leakage barrier layer is comprised of a material having a greater band gap than the first semiconductor layer and the second semiconductor layer.
Implementation Method 2
A first semiconductor layer is formed on the recessed surface of the fin structure that is doped to a first conductivity type. A second semiconductor layer is formed on the leakage barrier layer, wherein the second semiconductor layer is doped to a second conductivity type.
Data Source
AI summary
A method of forming a semiconductor device that includes forming a gate structure on a fin structure and etching the source and drain region portions of the fin structure to provide a recessed surface. A first semiconductor layer is formed on the recessed surface of the fin structure that is doped to a first conductivity type. A leakage barrier layer is formed on the first semiconductor layer. A second semiconductor layer is formed on the leakage barrier layer. The second semiconductor layer is doped to a second conductivity type.