Multi-Gate TFET Source-Side Gate Tunneling Mechanism
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Solution Overview
Problem
The scaling down of CMOS transistors leads to increasing power consumption due to rising leakage currents and difficulty in decreasing supply voltage, as conventional MOSFETs are limited by a subthreshold swing of 60 mV/decade, which TFETs have not effectively overcome in practice.
Innovation Solution
A Tunnel Field-Effect Transistor (TFET) design with a source-channel-drain structure, a reference gate structure, and a source-side gate structure, where the work function and electrostatic potential of the source-side gate structure are selected to enable tunneling at the interface between the source-side gate and reference gate structures, reducing the influence of dopant-related non-idealities and achieving a subthreshold swing less than 60 mV/decade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional MOSFET scaling is continued to increase packaging density, then device integration is improved, but power consumption increases due to leakage currents and inability to decrease supply voltage
Solution Approach 1:
The patent changes the fundamental operating mechanism from conventional drift-diffusion transport to band-to-band tunneling transport. This parameter change enables subthreshold swing below 60 mV/decade, allowing supply voltage to be decreased while maintaining switching performance, thereby reducing power consumption despite continued scaling for higher density
2Productivity
If conventional MOSFET scaling is continued, then integration density is improved, but leakage currents increase due to short channel effects
Solution Approach 1:
The patent changes the transport mechanism from drift-diffusion to direct band-to-band tunneling. This fundamental parameter change eliminates short channel effects that cause leakage currents in conventional MOSFETs, as the tunneling mechanism is inherently immune to channel length reduction, enabling continued scaling without increased leakage
3Device complexity
If TFET design uses conventional single gate structure, then device simplicity is maintained, but subthreshold swing cannot be reduced below 60 mV/decade in practice
Solution Approach 1:
The patent segments the gate control into two independent gates: a front gate that controls the tunnel barrier height and a back gate that controls the channel potential. This segmentation allows independent optimization of tunneling efficiency and subthreshold swing, enabling sub-60 mV/decade performance that cannot be achieved with a single gate structure
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 TFET device achieves a low subthreshold swing of less than 60 mV/decade, reduces the impact of dopant-related non-idealities, and is suitable for low-power and low-cost applications with improved performance compared to prior-art TFET devices.
Implementation Method 1
the tunnelling effect is based on band-to-band tunnelling
Data Source
AI summary
A Tunnel Field-Effect Transistor (TFET) is provided comprising a source-channel-drain structure of a semiconducting material. The source-channel-drain structure comprises a source region being n-type or p-type doped, a drain region oppositely doped than the source region and an intrinsic or lowly doped channel region situated between the source region and the drain region. The TFET further comprises a reference gate structure covering the channel region and a source-side gate structure aside of the reference gate structure wherein the work function and/or electrostatic potential of the source-side gate structure and the reference work function and/or electrostatic potential of the reference gate structure are selected for allowing the tunneling mechanism of the TFET device in operation to occur at the interface or interface region between the source-side gate structure and the reference gate structure in the channel region.