Hybrid-Well Ferroelectric FETs for Multi-State Memory
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Solution Overview
Problem
Existing ferroelectric field-effect transistors lack improved structures that leverage the polarization states of ferroelectric materials for enhanced logic states and storage density.
Innovation Solution
A semiconductor structure with a hybrid well configuration, comprising a semiconductor substrate with opposing conductivity type wells and a ferroelectric gate structure, allowing independent biasing of the wells to achieve multiple stable remanent polarization states in the ferroelectric layer, enabling more than two logic states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional ferroelectric field-effect transistor structure is used, then the device can achieve basic switching functionality with two logic states, but the storage density and cost efficiency are limited
Solution Approach 1:
The semiconductor substrate is segmented into multiple wells with different conductivity types (first well with first conductivity type, second well with second conductivity type). This segmentation allows the ferroelectric layer to experience different electric field conditions over each well, enabling multiple stable remanent polarization states and thereby increasing storage density beyond the conventional two-state limit.
Solution Approach 2:
Different regions of the semiconductor substrate are assigned different conductivity types locally. The first well has a first conductivity type while the second well has a second conductivity type, creating local quality variations. This allows independent biasing of each well region, which in turn enables the ferroelectric layer to establish multiple distinct polarization states depending on which well region is biased,从而实现多逻辑状态和更高存储密度。
2Quantity of substance
If independent well biasing is implemented to achieve multiple logic states, then storage density increases, but the device structure becomes more complex
Solution Approach 1:
The substrate is divided into multiple independently biasable well regions with different conductivity types. Each well can be independently biased to induce different polarization states in the overlying ferroelectric layer, enabling multiple logic states (more than two) without requiring a proportionally complex overall device architecture.
Solution Approach 2:
The hybrid well structure serves multiple functions: it provides the necessary electric field control for ferroelectric polarization, enables multiple logic states, and maintains compatibility with existing semiconductor fabrication processes. The same well structure that controls device operation also enables enhanced storage density, achieving multi-functionality.
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 structure enables ferroelectric field-effect transistors with increased storage density and reduced cost per bit by allowing for multiple logic states through independent well biasing, facilitating high-density memory arrays.
Implementation Method 1
a ferroelectric layer comprising a ferroelectric material... The threshold voltage of the ferroelectric field-effect transistor depends on the polarization state of the ferroelectric layer... achieve multiple stable remanent polarization states in the ferroelectric layer
Implementation Method 2
a dielectric layer arranged between the semiconductor layer and the semiconductor substrate
Data Source
AI summary
Structures including a ferroelectric field-effect transistor and methods of forming a structure including a ferroelectric field-effect transistor. The structure comprises a semiconductor substrate, a semiconductor layer, a dielectric layer arranged between the semiconductor layer and the semiconductor substrate, and first and second wells in the semiconductor substrate. The first well has a first conductivity type, and the second well has a second conductivity type opposite to the first conductivity type. A ferroelectric field-effect transistor comprises a gate structure on the semiconductor layer over the first well and the second well. The gate structure includes a ferroelectric layer comprising a ferroelectric material.