Hafnium Oxide Ferroelectric Tunnel Junction for CMOS Integration
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Solution Overview
Problem
Integration of materials like BaTiO3 and PbZr0.5Ti0.5O3 with large-scale integration (LSI) technology using complementary metal oxide silicon (CMOS) is highly difficult in ferroelectric tunnel junction (FTJ) devices, leading to challenges in scaling up ferroelectric memory devices.
Innovation Solution
A non-volatile memory device structure incorporating a first conductive layer, a paraelectric layer, a ferroelectric layer of hafnium oxide, and a high oxygen concentration conductive layer, with a sense circuit to read data based on tunneling current, where the conductive layers have specific oxygen ratios to manage oxygen content and improve ferroelectricity and endurance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferroelectric materials like BaTiO3 and PbZr0.5Ti0.5O3 are used in FTJ devices, then ferroelectric performance is improved, but integration with CMOS LSI technology becomes highly difficult
Solution Approach 1:
The patent changes the material parameter from traditional ferroelectric materials (BaTiO3, PbZr0.5Ti0.5O3) to hafnium oxide, which has compatible processing parameters with CMOS technology. This material substitution enables integration while maintaining ferroelectric functionality through controlled oxygen content and crystalline structure.
Solution Approach 2:
The patent creates a composite structure combining hafnium oxide ferroelectric layer with metal nitride conductive layers and oxygen supply layers. This composite approach achieves both ferroelectric performance and CMOS compatibility by combining materials with complementary properties.
2Reliability
If oxygen content in conductive layers is increased, then ferroelectricity and endurance characteristics are improved, but oxygen diffusion may cause polarization degradation
Solution Approach 1:
The patent segments the device into distinct functional layers: oxygen supply layers (metal nitride), oxygen buffer layers (insulating layers with oxygen), and ferroelectric layers (hafnium oxide). This segmentation allows controlled oxygen diffusion from the supply layer through the buffer layer to the ferroelectric layer, achieving both improved endurance and polarization stability.
Solution Approach 2:
The patent introduces insulating layers with oxygen content as intermediary buffers between the metal nitride layer and the hafnium oxide ferroelectric layer. These intermediary layers mediate oxygen diffusion, providing sufficient oxygen to improve ferroelectricity while preventing excessive oxygen that would cause polarization degradation.
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 proposed structure enhances the endurance characteristics of FTJ devices by controlling oxygen content, preventing polarization degradation, and improving the number of data rewrites, thus scaling up the integration of ferroelectric memory devices effectively.
Implementation Method 1
a second conductive layer including metal nitride, the metal nitride absorbing oxygen
Implementation Method 2
a sense circuit configured to read data based on tunneling current flow between the first conductive layer and the second conductive layer through the paraelectric layer and the ferroelectric layer
Implementation Method 3
a ferroelectric layer disposed between the paraelectric layer and the second conductive layer, the ferroelectric layer including hafnium oxide
Data Source
AI summary
A non-volatile memory device according to an embodiment includes a first conductive layer, a second conductive layer including metal nitride, the metal nitride absorbing oxygen, a paraelectric layer disposed between the first conductive layer and the second conductive layer, a ferroelectric layer disposed between the paraelectric layer and the second conductive layer, the ferroelectric layer including hafnium oxide, at least one third conductive layer disposed on opposite side of at least one of the first conductive layer and the second conductive layer to the ferroelectric layer, the at least one third conductive layer including metal oxide, the metal oxide having oxygen ratio larger than stoichiometric ratio, and a sense circuit configured to read data based on tunneling current flow between the first conductive layer and the second conductive layer through the paraelectric layer and the ferroelectric layer.