FinFET Gate Electrodes with Dual Work-Function Metals
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Solution Overview
Problem
FinFET devices face challenges in tuning voltage thresholds for low-power SRAM applications, as high doping to achieve higher voltage thresholds increases device mismatch and potential operation failure at minimum voltages, limiting the balance between fast read and stable write operations.
Innovation Solution
The use of at least two different work-function metals for gate electrodes in FinFETs allows for distinct threshold voltages in read and write ports, enabling lower leakage and faster read operations by setting appropriate voltage thresholds for each port.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high doping is used to achieve higher voltage thresholds in FinFETs, then write port stability is improved, but device mismatch increases and operation reliability deteriorates
Solution Approach 1:
The patent applies local quality by using different doping concentrations in different regions of the FinFET device. Specifically, the read port FinFETs use lower doping concentrations to achieve lower voltage thresholds for fast read operations, while the write port FinFETs use higher doping concentrations to achieve higher voltage thresholds for stable write operations. This spatial variation in doping quality resolves the contradiction by allowing each port to have optimized characteristics without affecting the other port's performance.
2Ease of manufacture
If uniform doping is used in all FinFETs, then manufacturing simplicity is maintained, but the ability to achieve distinct voltage thresholds for different ports is lost
Solution Approach 1:
The patent implements local quality by applying different doping concentrations to different ports of the SRAM cell. The read port FinFETs receive a first doping concentration optimized for low-voltage operation, while the write port FinFETs receive a second doping concentration optimized for stability. This approach maintains manufacturing feasibility while achieving the adaptability needed for distinct voltage thresholds in different ports.
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 power consumption and improves the speed and reliability tradeoffs in SRAMs by allowing for lower voltage thresholds in read ports and higher thresholds in write ports, enhancing data stability and reducing leakage.
Implementation Method 1
use at least two different work-function metals for gate electrodes for FinFETs of the same conductivity type
Data Source
AI summary
Some embodiments relate to an integrated circuit including fin field effect transistors (FinFETs) thereon. The integrated circuit includes first and second active fin regions having a first conductivity type and spaced apart from one another. A gate dielectric layer is disposed over the first and second active fin regions. First and second gate electrodes are disposed over the first and second active fin regions, respectively. The first and second gate electrodes are also disposed over the gate dielectric layer. The first and second gate electrodes are electrically coupled together and are electrically separated from the first and second active fin regions by the gate dielectric layer. The first gate electrode is made of a first metal having a first workfunction, and the second gate electrode is made of a second metal having a second workfunction that differs from the first workfunction.