Variable Resistance Memory Element with Tantalum Oxynitride Barrier
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Solution Overview
Problem
Conventional variable resistance elements face issues with resistance change characteristics deteriorating due to thermal budget and stability at low voltages, making them unsuitable for reliable operation.
Innovation Solution
A nonvolatile memory element with a two-layer structure comprising an oxygen- and/or nitrogen-deficient tantalum oxynitride layer and a tantalum oxide layer, where the oxygen- and/or nitrogen-deficient tantalum oxynitride layer inhibits oxygen diffusion and allows for stable resistance changes at low voltages by controlling oxygen ion movement, with specific compositional and thickness ratios to optimize resistivity and voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer tantalum oxide structure is used, then the device structure is simple, but the resistance change characteristics deteriorate due to thermal budget and stable operation at low voltages is difficult
Solution Approach 1:
The variable resistance layer is divided into two distinct layers: a first tantalum oxide layer (Ta2O5) and a second oxygen-deficient tantalum oxide layer (TaOx). This segmentation allows each layer to perform specific functions - the first layer provides structural stability while the second layer enables reliable resistance switching at low voltages, resolving the contradiction between structural simplicity and functional reliability.
Solution Approach 2:
The invention uses a composite structure combining two different tantalum oxide materials with distinct oxygen concentrations. The Ta2O5 layer (high oxygen content) and TaOx layer (low oxygen content) work together to provide both thermal stability and excellent resistance change characteristics, achieving reliable operation without excessive structural complexity.
2Ease of manufacture
If conventional variable resistance elements are used, then manufacturing is straightforward, but stable operation at low voltages is difficult
Solution Approach 1:
The invention changes the oxygen concentration parameter by creating a two-layer structure with different oxygen stoichiometries (Ta2O5 and TaOx). This parameter variation enables the device to operate stably at low voltages while maintaining compatibility with conventional manufacturing processes, as both layers can be formed using standard sputtering techniques with controlled oxygen partial pressures.
3Productivity
If thermal budget is applied to conventional elements, then manufacturing processes can be completed, but oxygen concentration profile deteriorates
Solution Approach 1:
The first tantalum oxide layer (Ta2O5) acts as a cushioning layer that protects the oxygen concentration profile during subsequent thermal processing. This layer has high thermal stability and prevents oxygen diffusion that would otherwise deteriorate the composition, allowing standard manufacturing thermal budgets to be applied without compromising material stability.
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 enables stable operation at low voltages, reduces oxygen concentration profile deterioration, and enhances resistance change characteristics, allowing the nonvolatile memory element to function effectively with reduced voltage requirements compared to conventional elements.
Implementation Method 1
The oxygen- and/or nitrogen-deficient tantalum oxynitride layer inhibits oxygen diffusion and allows for stable resistance changes at low voltages by controlling oxygen ion movement
Implementation Method 2
changes to a low resistance state due to oxygen ions moving from the tantalum oxide layer to the oxygen- and/or nitrogen-deficient tantalum oxynitride layer; and changes to a high resistance state due to oxygen ions moving from the oxygen- and/or nitrogen-deficient tantalum oxynitride layer to the tantalum oxide layer
Data Source
AI summary
A nonvolatile memory element which inhibits deterioration of an oxygen concentration profile of a variable resistance layer due to a thermal budget and is able to stably operate at low voltages, and a method for manufacturing the nonvolatile memory element are provided. The nonvolatile memory element includes a first electrode layer formed above a substrate, a variable resistance layer disposed on the first electrode layer, and a second electrode layer disposed on the variable resistance layer, and the variable resistance layer has a two-layer structure in which an oxygen- and/or nitrogen-deficient tantalum oxynitride layer and a tantalum oxide layer are stacked.