FinFET Cell Boundary Threshold Tuning for Leakage Reduction
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the significant leakage current caused by continuous active regions in FinFET devices, which is exacerbated when abutting active regions are of the same type, leading to device failure and performance degradation, and existing solutions like filler layers result in area penalties.
Innovation Solution
The solution involves increasing the threshold voltage at the cell boundary by changing the photomask logic operation, performing a threshold voltage implant, or using a silicon germanium channel to improve isolation between neighboring cells, thereby reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If continuous active regions are used to reduce cell size, then device integration density is improved, but leakage current increases significantly
Solution Approach 1:
The continuous active region is segmented by introducing dummy fins at cell boundaries. These dummy fins act as isolation structures that divide the continuous active region into separate segments, preventing direct leakage current flow between adjacent cells while maintaining the compact layout.
Solution Approach 2:
Dummy fins serve as intermediary structures placed at cell boundaries. These intermediary elements provide electrical isolation between adjacent active regions of the same type, blocking leakage current paths without requiring additional filler layers that would increase area.
2Object-generated harmful factors
If filler layers are added to reduce leakage current, then leakage current is reduced, but device area increases
Solution Approach 1:
The dummy fins serve multiple functions: they act as isolation structures to block leakage current, maintain the continuous active region architecture for compact cell design, and provide consistent electrical characteristics. This multi-functionality eliminates the need for separate filler layers, avoiding area penalty.
Solution Approach 2:
The threshold voltage of dummy fins is engineered to be higher than adjacent active fins, creating a potential barrier that blocks leakage current. By changing the electrical parameter (threshold voltage) rather than adding physical filler layers, leakage is reduced without increasing device area.
3Productivity
If abutting active regions of the same type are used, then cell density is improved, but leakage current increases due to threshold voltage matching
Solution Approach 1:
Dummy fins are strategically placed only at cell boundaries where leakage current paths exist, while maintaining standard active fins within cells. This localized modification provides isolation exactly where needed without affecting the overall continuous active region architecture and cell density.
Solution Approach 2:
Instead of trying to lower the threshold voltage of active fins to reduce leakage, the invention inverts the approach by raising the threshold voltage of dummy fins above that of adjacent active fins. This creates a potential barrier that blocks leakage current while maintaining the same-type active region configuration for high density.
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 decreases leakage current and enhances isolation between neighboring cells, improving device performance and reliability without increasing device area.
Implementation Method 1
or using a silicon germanium channel to improve isolation between neighboring cells
Implementation Method 2
performing a threshold voltage implant, or using a silicon germanium channel
Data Source
AI summary
A method and structure for mitigating leakage current in devices that include a continuous active region. In some embodiments, a threshold voltage at the cell boundary is increased by changing a photomask logic operation (LOP) to reverse a threshold voltage type at the cell boundary. Alternatively, in some cases, the threshold voltage at the cell boundary is increased by performing a threshold voltage implant (e.g., an ion implant) at the cell boundary, and into a dummy gate disposed at the cell boundary. Further, in some embodiments, the threshold voltage at the cell boundary is increased by use of a silicon germanium (SiGe) channel at the cell boundary. In some cases, the SiGe may be disposed within the substrate at the cell boundary and/or the SiGe may be part of the dummy gate disposed at the cell boundary.