Anti-Ferroelectric Memory With Fixed Charge Pattern
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Solution Overview
Problem
Current nonvolatile memory devices using ferroelectric materials face challenges in maintaining polarization states without external electric fields, limiting their effectiveness in storing data reliably.
Innovation Solution
A nonvolatile memory device incorporating an anti-ferroelectric material with a tunnel barrier pattern and electrodes having different work functions, along with a fixed charge pattern, to create an internal electric field that maintains polarization even without external voltage, enhancing switching speed and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferroelectric materials are used to store data, then data storage capability is achieved, but the ability to maintain polarization states without external electric fields is limited
Solution Approach 1:
A fixed charge layer is introduced as an intermediary between the substrate and the anti-ferroelectric tunnel junction. This fixed charge layer generates an internal electric field that acts on the anti-ferroelectric material to maintain its polarization state without requiring external electric fields, thereby resolving the contradiction between data storage reliability and polarization maintenance duration
Solution Approach 2:
The patent changes the material parameter from conventional ferroelectric materials to anti-ferroelectric materials (such as Hf1-xZrxO3 with specific compositions). This material parameter change enables the system to maintain polarization states more effectively through the internal electric field generated by the fixed charge layer, improving both data storage reliability and polarization maintenance duration
2Speed
If anti-ferroelectric material is used with fixed charge pattern, then switching speed is improved, but device structure becomes more complex
Solution Approach 1:
The fixed charge layer is merged with the existing device structure by forming it within the tunnel barrier layer or at the interface between the substrate and the lower electrode. This integration approach introduces the necessary internal electric field mechanism without significantly increasing device structure complexity, while still achieving improved switching speed through the anti-ferroelectric material's response to the internal field
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 device achieves reliable data storage with improved switching speed and durability by utilizing an anti-ferroelectric material and a fixed charge pattern to maintain polarization internally, enabling efficient data retention without external electric fields.
Implementation Method 1
a fixed charge pattern in contact with the lower electrode and spaced apart from the tunnel barrier pattern with the lower electrode therebetween... create an internal electric field that maintains polarization even without external voltage
Implementation Method 2
anti-ferroelectric materials refer to materials that have no spontaneous electrical polarization in a state where no external electric field is applied, but exhibit the same characteristics as ferroelectric materials when an electric field is applied
Implementation Method 3
the lower electrode includes a first material, the upper electrode includes a second material, and the first material and the second material have different work functions
Data Source
AI summary
Provided is a nonvolatile memory device including a lower electrode on a substrate, an upper electrode on the lower electrode, a tunnel barrier pattern between the lower electrode and the upper electrode, and a fixed charge pattern in contact with the lower electrode and spaced apart from the tunnel barrier pattern with the lower electrode therebetween. The tunnel barrier pattern includes an anti-ferroelectric material. The lower electrode includes a first material. The upper electrode includes a second material. The first material and the second material have different work functions.