Super Steep Retrograde Channel for Threshold Voltage Control
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Solution Overview
Problem
Existing semiconductor devices face challenges in adjusting threshold voltage post-manufacturing to accommodate changing operating conditions, as conventional methods require significant body biasing voltage changes to achieve small threshold voltage adjustments, leading to increased static current leakage and compatibility issues with existing design and manufacturing techniques.
Innovation Solution
The implementation of a semiconductor device with a super steep retrograde channel region formed at a depth 10 to 30 times the gate oxide thickness, combined with a raised source/drain structure, allows for a more linear adjustment of threshold voltage with smaller body biasing voltage changes, reducing static current leakage and maintaining compatibility with existing manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional body biasing voltage adjustment methods are used, then threshold voltage can be adjusted, but significant voltage changes are required to achieve small threshold voltage adjustments, leading to increased static current leakage
Solution Approach 1:
The patent changes the physical parameters of the semiconductor device by forming a super steep retrograde channel region with a specific doping profile where the dopant concentration increases with depth. This parameter change in the channel structure enables more efficient threshold voltage control with smaller body biasing voltage changes, thereby reducing static current leakage while maintaining adjustment capability.
Solution Approach 2:
The patent applies local quality by creating a retrograde channel region with non-uniform dopant distribution specifically in the channel area, while keeping other regions of the device unchanged. This localized modification of the channel's doping profile enables improved voltage control characteristics without affecting other device functionalities.
2Ease of operation
If super steep retrograde channel region is formed at depth 10 to 30 times gate oxide thickness, then threshold voltage adjustment efficiency improves, but device structure complexity increases
Solution Approach 1:
The patent resolves the complexity issue by transitioning from a conventional planar channel structure to a vertically stratified retrograde channel structure. By organizing dopant atoms in layers at different depths (10 to 30 times gate oxide thickness below the surface), the invention achieves improved adjustment efficiency through vertical dimensionality while maintaining compatibility with standard planar device fabrication.
Solution Approach 2:
The super steep retrograde channel region is formed during the manufacturing process before final device operation. This preliminary structuring of the channel with predetermined dopant distribution enables the device to inherently achieve better threshold voltage control efficiency without requiring complex external control mechanisms during operation.
3Reliability
If new channel structure is implemented, then threshold voltage control improves, but compatibility with existing manufacturing techniques may be compromised
Solution Approach 1:
The patent achieves universality by designing a super steep retrograde channel structure that can be integrated into existing semiconductor manufacturing workflows. The channel formation process is compatible with standard doping and fabrication techniques, allowing the enhanced threshold voltage control to be implemented without requiring entirely new manufacturing equipment or processes.
Data Source
AI summary
Systems and methods for raised source/drain with super steep retrograde channel are described. In accordance with a first embodiment, a semiconductor device comprises a substrate comprising a surface and a gate oxide disposed above the surface comprising a gate oxide thickness. The semiconductor device further comprises a super steep retrograde channel region formed at a depth below the surface. The depth is about ten to thirty times the gate oxide thickness. Embodiments may provide a more desirable body biasing voltage to threshold voltage characteristic than is available under the conventional art.