Ferroelectric Field-Effect Transistor Interlayers for Wider Memory Windows
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Solution Overview
Problem
Existing ferroelectric field effect transistors (FeFETs) face challenges in achieving a wide memory window and efficient polarization switching due to direct contact between the channel layer and ferroelectric layer, leading to reduced polarization switching and increased leakage current.
Innovation Solution
Incorporating an oxide semiconductor channel with a higher concentration of oxygen vacancies in the channel intermediate layer and a gate intermediate layer with a gradient of nitrogen and oxygen concentrations to enhance polarization switching and reduce capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a ferroelectric layer is placed in direct contact with a channel layer, then the device structure is simplified, but the polarization switching capability is reduced and leakage current increases
Solution Approach 1:
An intermediate layer is introduced between the ferroelectric layer and the channel layer to act as a mediator. This intermediate layer prevents direct contact while enabling effective interaction, thereby maintaining polarization switching capability and reducing leakage current without significantly complicating the overall device structure.
Solution Approach 2:
The intermediate layer is positioned specifically at the interface region where the ferroelectric layer contacts the channel layer. This localized modification improves the local electrical properties at the critical interface without altering the bulk properties of the main layers, thus enhancing polarization switching and reducing leakage current while keeping the rest of the device structure simple.
2Reliability
If oxygen vacancies are increased in the channel intermediate layer, then polarization switching is enhanced, but leakage current increases
Solution Approach 1:
The concentration of oxygen vacancies in the intermediate layer is precisely controlled and optimized to achieve the desired balance. By adjusting this parameter, the polarization switching capability is enhanced while the increase in leakage current is kept within acceptable limits through careful parameter selection.
Solution Approach 2:
Oxygen vacancies are concentrated specifically in the intermediate layer rather than uniformly distributed throughout the entire device. This localized distribution of oxygen vacancies enhances polarization switching at the critical interface while minimizing the impact on overall leakage current by confining the defect density to a specific region.
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 solution increases the memory window and polarization switching capability of FeFETs by allowing bidirectional polarization switching and reducing leakage current, thereby improving operational efficiency.
Implementation Method 1
a concentration of oxygen vacancies in the channel intermediate layer may be greater than a concentration of oxygen vacancies in the channel layer
Implementation Method 2
a gate intermediate layer with a gradient of nitrogen and oxygen concentrations to enhance polarization switching and reduce capacitance
Data Source
Figure 1~2
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Figure 5~6
AI summary
A ferroelectric field effect transistor (100a) includes a channel layer (103), a gate electrode (101) facing the channel layer, a ferroelectric layer (102) between the channel layer and the gate electrode, a channel intermediate layer (104) between the channel layer and the ferroelectric layer; and a gate intermediate layer (107) between the gate electrode and the ferroelectric layer, wherein the channel layer and the channel intermediate layer each include an oxide semiconductor material, a concentration of oxygen vacancies in the channel intermediate layer is greater than a concentration of oxygen vacancies in the channel layer,the gate intermediate layer comprises amorphous silicon oxynitride, and a concentration of nitrogen in the amorphous silicon oxynitride gate intermediate layer increases from the surface of the gate intermediate layer facing the gate electrode toward the surface of the gate intermediate layer facing the ferroelectric layer.