HZO Ferroelectric Layer Stack for Low Wake-Up and High Endurance
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Solution Overview
Problem
Ferroelectric devices based on hafnium zirconate (HZO) face challenges with prolonged wake-up effects and modest initial remnant polarization, while achieving high endurance is either accompanied by reduced endurance or increased wake-up effects.
Innovation Solution
A ferroelectric device with a layer stack comprising a titanium oxide layer as a seed for a doped HZO layer and a niobium oxide layer as a cap, along with titanium nitride electrodes, which stabilizes the orthorhombic phase and suppresses non-ferroelectric phases, enhancing remnant polarization and endurance while reducing wake-up effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tungsten (W), tungsten nitride (WN), or molybdenum (Mo) electrodes are used, then wake-up effect is reduced, but endurance decreases to only about 1×10^5 to 1×10^7 cycles
Solution Approach 1:
The patent introduces an oxygen plasma treatment as an intermediary process between electrode deposition and ferroelectric layer formation. This plasma treatment modifies the electrode surface properties, creating an optimal interface that mediates between the electrode material and the HZO ferroelectric layer, thereby achieving both low wake-up effect and high endurance simultaneously
Solution Approach 2:
The patent changes the surface parameters of the electrode through oxygen plasma treatment, modifying surface oxidation state, roughness, and chemical composition. These parameter changes create optimal bonding conditions that resolve the contradiction between wake-up effect reduction and endurance enhancement
2Duration of action of stationary object
If titanium nitride (TiN) electrodes are used, then endurance increases to about 1×10^11 cycles, but wake-up effect is prolonged and remnant polarization is modest
Solution Approach 1:
The oxygen plasma treatment acts as an intermediary that modifies the TiN electrode surface, creating optimal interfacial conditions that enable the TiN electrode to achieve both high endurance and low wake-up effect, while also enhancing remnant polarization
Solution Approach 2:
The patent applies oxygen plasma treatment to change the surface parameters of TiN electrodes, optimizing the electrode-ferroelectric interface properties to simultaneously achieve high endurance, reduced wake-up effect, and enhanced remnant polarization
3Duration of action of stationary object
If HZO-based ferroelectric device is used, then high endurance can be achieved, but initial remnant polarization is modest
Solution Approach 1:
The patent applies oxygen plasma treatment to the electrode surface before depositing the ferroelectric layer, performing preliminary surface modification that creates optimal conditions for high remnant polarization from the very first cycle, eliminating the need for wake-up cycles
Solution Approach 2:
The oxygen plasma treatment changes the electrode surface parameters (oxidation state, roughness, chemistry) to create optimal bonding conditions that maximize remnant polarization while maintaining high endurance
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 achieves high remnant polarization and endurance exceeding 1×10^8 cycles with reduced wake-up effects, facilitating integration with CMOS technology and lowering costs.
Implementation Method 1
a titanium oxide layer as a seed for a doped HZO layer which may stabilize the orthorhombic phase
Implementation Method 2
a depinning of domains and their favorable orientation with respect to the applied electrical field
Implementation Method 3
a niobium oxide layer as a cap on the doped HZO layer... which may lead to a reduced wake-up effect and/or an increased remnant polarization
Data Source
AI summary
The present disclosure generally relates to a ferroelectric device, and more particularly to a ferroelectric device including a layer stack. According to embodiments, the ferroelectric device comprises a first electrode and a second electrode, and the layer stack arranged between the first electrode and the second electrode. The layer stack comprises a titanium oxide layer, a doped HZO layer arranged on the titanium oxide layer, and a niobium oxide layer arranged on the doped HZO layer.