ETSOI Transistor Leakage Reduction via Deposition
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Solution Overview
Problem
MOSFET devices suffer from performance loss due to drain-to-substrate leakage, particularly in extremely thin semiconductor-on-insulator (ETSOI) substrates, where forming source and drain regions through implantation damages the thin layer and prevents recrystallization without a seed layer.
Innovation Solution
The formation of source and drain regions using an n-type material, such as aluminum doped zinc oxide, deposited directly on the buried dielectric within the thin semiconductor layer, eliminating the need for recrystallization and reducing leakage by isolating the base substrate with a buried dielectric.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If implantation methods are used to form source and drain regions in ETSOI, then doping can be achieved, but the thin layer is damaged and recrystallization is prevented
Solution Approach 1:
The patent extracts the thin semiconductor layer from the substrate and forms source and drain regions in the suspended configuration, eliminating the need for implantation into the thin layer. This removes the damaging implantation process while maintaining the ability to form functional source and drain regions through deposition on the exposed substrate beneath the suspended layer
Solution Approach 2:
Instead of forming source and drain regions by implanting into the thin semiconductor layer from above, the patent inverts the approach by depositing material onto the substrate beneath the suspended thin layer. This reverse approach avoids damaging the thin layer while achieving the same functional result
2Object-affected harmful factors
If ETSOI is used to reduce drain-to-substrate leakage, then leakage is reduced, but source and drain regions cannot be formed without damaging the thin layer
Solution Approach 1:
The patent segments the semiconductor structure into a suspended thin layer portion and a substrate portion, allowing source and drain regions to be formed in the substrate portion through deposition. This segmentation enables leakage reduction through the suspended configuration while maintaining ease of manufacture through standard deposition processes
Solution Approach 2:
The suspended thin semiconductor layer acts as an intermediary that isolates the channel region from the substrate, preventing drain-to-substrate leakage. Meanwhile, the substrate beneath serves as the medium for forming source and drain regions through deposition, resolving the contradiction between leakage reduction and manufacturability
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 enhances mobility and reduces leakage in MOSFET devices by forming stable source and drain regions without damaging the thin layer, maintaining high field effect mobility and eliminating the need for recrystallization.
Implementation Method 1
an n-type material deposited on the buried dielectric within a thickness of the thin semiconductor layer
Data Source
AI summary
A semiconductor device includes an extremely thin semiconductor-on-insulator substrate (ETSOI) having a base substrate, a thin semiconductor layer and a buried dielectric therebetween. A device channel is formed in the thin semiconductor layer. Source and drain regions are formed at opposing positions relative to the device channel. The source and drain regions include an n-type material deposited on the buried dielectric within a thickness of the thin semiconductor layer. A gate structure is formed over the device channel.