Semiconductor Junction Structure Using an Anti-Doping Epitaxial Layer
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Solution Overview
Problem
The diffusion of dopants from the source/drain regions into the channel regions in semiconductor devices leads to unintended off-state current leakage, compromising the integrity of the channel composition and device performance.
Innovation Solution
Incorporation of an anti-doping epitaxial layer between the channel regions and source/drain regions, which is formed using an in-situ or ex-situ epitaxy process, preventing dopant migration and ensuring an abrupt junction doping profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If source/drain regions are formed in semiconductor devices, then device functionality is achieved, but dopant diffusion into channel regions causes off-state current leakage
Solution Approach 1:
An anti-doping epitaxial layer is introduced as an intermediary between the source/drain regions and the channel region. This intermediate layer acts as a barrier that prevents dopant diffusion from the source/drain regions into the channel, thereby eliminating the harmful off-state current leakage while maintaining device functionality.
Solution Approach 2:
The anti-doping epitaxial layer is formed in advance during the epitaxial growth process, before the source/drain regions are fully formed and before dopant diffusion can occur. This preliminary formation of the protective layer ensures that when source/drain regions are subsequently created, the barrier is already in place to prevent harmful dopant migration.
2Ease of manufacture
If dopant diffusion is allowed to occur, then source/drain region formation is simplified, but channel composition integrity is compromised
Solution Approach 1:
The anti-doping epitaxial layer serves as a protective intermediary that preserves channel composition integrity. By placing this layer between the source/drain regions and the channel, it prevents dopant contamination of the channel region while allowing the source/drain regions to be formed using standard processes.
Solution Approach 2:
The anti-doping epitaxial layer is selectively formed only in the regions where dopant diffusion protection is needed - specifically at the interfaces between source/drain regions and the channel. This localized application maintains channel composition integrity without interfering with the overall source/drain region formation process.
3Object-generated harmful factors
If anti-doping epitaxial layer is added, then off-state current leakage is reduced, but device structure becomes more complex
Solution Approach 1:
The anti-doping epitaxial layer is designed with optimized parameters including thin thickness (typically nanometer scale) and specific material composition that differs from the underlying channel material. These parameter changes enable the layer to function as an effective dopant barrier while minimizing its impact on overall device structure and maintaining manufacturing simplicity.
Solution Approach 2:
The anti-doping epitaxial layer is formed using composite material structures where a thin film of specific semiconductor material (such as SiGe or other alloy compositions) is deposited on the silicon channel. This composite structure provides the necessary dopant blocking functionality while maintaining compatibility with existing semiconductor fabrication processes.
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 anti-doping epitaxial layer enhances device performance by reducing channel resistance and minimizing off-state current leakage, while maintaining manufacturing reliability and yield.
Implementation Method 1
The diffusion of dopants from the source/drain regions into the channel regions in semiconductor devices leads to unintended off-state current leakage
Implementation Method 2
Incorporation of an anti-doping epitaxial layer between the channel regions and source/drain regions, which is formed using an in-situ or ex-situ epitaxy process
Data Source
AI summary
A method of forming a semiconductor device includes a number of operations. Source/drain recesses are formed on opposing side of a channel region over a substrate. Anti-doping epitaxial layers are formed over the source/drain recesses, wherein the anti-doping epitaxial layers have a first conductivity type. Source/drain epitaxial regions are formed over the anti-doping epitaxial layers, wherein the source/drain epitaxial regions have a second conductivity type different from the first conductivity type. A gate structure is formed over the channel regions.