Trench Ferroelectric Capacitor Spacers for Sidewall Strain Control
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Solution Overview
Problem
Traditional thin-film ferroelectric capacitors suffer from low retention and weak polarization due to strong depolarization, limiting their endurance cycles and memory window, especially at high temperatures, necessitating improved materials and stack designs for enhanced reliability and charge density.
Innovation Solution
The implementation of epitaxial strain engineering in ferroelectric/anti-ferroelectric oxide thin films and electrodes, utilizing spacers to apply tensile stress and suppress the non-polar monoclinic phase, thereby increasing the polar orthorhombic or tetragonal phase, which enhances the memory window and reliability of the capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional thin-film ferroelectric capacitors are used, then device complexity is reduced, but retention and polarization are weakened due to strong depolarization
Solution Approach 1:
The patent employs composite material structures including ferroelectric oxide layers combined with electrode materials (such as Pt, IrO2, RuO2) and spacer materials (such as TiN, TaN, WN). These composite structures enable simultaneous achievement of strong polarization, long retention, and stress control to suppress depolarization effects.
Solution Approach 2:
The patent introduces localized spacer structures positioned adjacent to the ferroelectric capacitor to apply tensile stress specifically to the ferroelectric layer. This local stress application enhances polarization and suppresses the non-polar monoclinic phase without requiring complete redesign of the entire device stack.
2Reliability
If traditional thin-film ferroelectric capacitors are used, then manufacturing process is simplified, but polarization is weak due to strong depolarization
Solution Approach 1:
The patent utilizes parameter changes in the form of applying tensile stress to the ferroelectric layer through spacer structures. This stress parameter modification shifts the phase equilibrium, suppressing the non-polar monoclinic phase and stabilizing the polar orthorhombic or tetragonal phase, thereby enhancing polarization without complicating the overall manufacturing process.
Solution Approach 2:
The spacer structures serve as intermediary elements that mediate between the electrode and the ferroelectric layer. These spacers apply controlled tensile stress to the ferroelectric material, enhancing its polarization properties while maintaining compatibility with existing manufacturing processes.
3Reliability
If traditional thin-film ferroelectric capacitors are used, then device structure is simple, but retention is low due to strong depolarization
Solution Approach 1:
The patent introduces localized spacer structures positioned adjacent to the ferroelectric capacitor to apply tensile stress specifically to the ferroelectric layer. This local stress application enhances polarization and suppresses the non-polar monoclinic phase without requiring complete redesign of the entire device stack.
Solution Approach 2:
The patent employs composite material structures including ferroelectric oxide layers combined with electrode materials (such as Pt, IrO2, RuO2) and spacer materials (such as TiN, TaN, WN). These composite structures enable simultaneous achievement of strong polarization, long retention, and stress control to suppress depolarization effects.
4Reliability
If spacers are added to apply tensile stress, then memory window and reliability are improved, but device complexity increases
Solution Approach 1:
The patent introduces localized spacer structures positioned adjacent to the ferroelectric capacitor to apply tensile stress specifically to the ferroelectric layer. This local stress application enhances polarization and suppresses the non-polar monoclinic phase without requiring complete redesign of the entire device stack.
Solution Approach 2:
The spacer structures serve as intermediary elements that mediate between the electrode and the ferroelectric layer. These spacers apply controlled tensile stress to the ferroelectric material, enhancing its polarization properties and memory window while maintaining compatibility with existing manufacturing processes.
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
This approach significantly improves the memory window and reliability of ferroelectric/anti-ferroelectric oxide thin films, enabling longer endurance cycles and stable ferroelectric behavior even at elevated temperatures.
Implementation Method 1
a fourth structure adjacent to the first structure, wherein the fourth structure is to provide tensile stress to the ferroelectric or anti-ferroelectric material
Data Source
AI summary
Described is a ferroelectric-based capacitor that improves reliability of a ferroelectric memory by providing tensile stress along a plane (e.g., x-axis) of a ferroelectric or anti-ferroelectric material of the ferroelectric/anti-ferroelectric based capacitor. Tensile stress is provided by a spacer comprising metal, semimetal, or oxide (e.g., metal or oxide of one or more of: Al, Ti, Hf, Si, Ir, or N). The tensile stress provides polar orthorhombic phase to the ferroelectric material and tetragonal phase to the anti-ferroelectric material. As such, memory window and reliability of the ferroelectric/anti-ferroelectric oxide thin film improves.