HfOx/AlOx Stacked Memory Element for High Resistance Ratio
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Solution Overview
Problem
Existing resistance change type nonvolatile memory elements face challenges such as low resistance change ratio, difficulty in electrode processing, and high material costs, particularly in achieving stable and high-speed rewriting characteristics.
Innovation Solution
A nonvolatile memory element with a stacked structure comprising a first metal oxide layer containing Hf and O, and a second metal oxide layer containing Al and O, formed using magnetron sputtering under specific reactive gas and inert gas ratios to achieve a high resistance change ratio, with titanium nitride electrodes for improved etching and cost reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional resistance change layer (single metal oxide) is used, then the device structure is simple, but the resistance change ratio is low
Solution Approach 1:
The patent applies composite materials by stacking multiple metal oxide layers (HfOx and AlOx) to form a variable resistance layer. This composite structure achieves a resistance change ratio of 10^4 or more, solving the limitation of single-material resistance change layers while maintaining manufacturability through standard sputtering processes.
2Reliability
If Pt electrodes are used, then the resistance change characteristics are stable, but the material cost and etching difficulty increase
Solution Approach 1:
The patent replaces expensive Pt electrodes with TiN (titanium nitride) electrodes, which are cheaper and easier to process. The TiN electrodes achieve comparable performance with lower material cost and simpler etching characteristics, aligning with the principle of using more economical materials when performance requirements are met.
Solution Approach 2:
The patent modifies the electrode material composition from Pt to TiN, changing the physical and chemical parameters of the electrode. This parameter change reduces both material cost and processing complexity while maintaining the necessary electrical characteristics for stable resistance change operation.
3Manufacturing precision
If the forming voltage is increased to improve resistance change ratio, then the resistance change ratio increases, but the power consumption and device stress increase
Solution Approach 1:
The stacked HfOx and AlOx layers create a composite variable resistance layer that achieves high resistance change ratio (10^4 or more) at lower forming voltages compared to single-layer structures. The interface between layers facilitates filament formation at reduced voltage, solving the contradiction between resistance change ratio and power consumption.
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 a significant increase in resistance change ratio without increasing forming voltage, enhancing the stability and efficiency of the memory element's operation while reducing material costs and processing complexities.
Implementation Method 1
forming a first metal oxide layer containing Hf and O and a second metal oxide layer containing Al and O in a stacked manner by a magnetron sputtering method
Data Source
AI summary
The present invention provides a nonvolatile memory element, in a nonvolatile memory element having a variable resistance layer possessing a stacked structure, in which the variable resistance layer has a high resistance change ratio, and a method of manufacturing the same. The nonvolatile memory element according to one embodiment of the present invention includes a first electrode, a second electrode, and a variable resistance layer which is interposed between the first electrode and second electrode and in which the resistance value changes into at least two different resistance states. The variable resistance layer possesses a stacked structure having a first metal oxide layer containing Hf and O, and a second metal oxide layer that is provided between the first metal oxide layer and at least one of the first electrode and the second electrode and contains Al and O.