Metal Oxide Rectifying Portions for Non-Volatile Memory Miniaturization
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Solution Overview
Problem
The existing cross-point memory devices face challenges in miniaturization due to the high-temperature manufacturing process of silicon diodes, which deteriorates the resistance change material and limits the reduction in size, necessitating a rectifying element with a high ON/OFF ratio that can be easily miniaturized without compromising the resistance change material's characteristics.
Innovation Solution
A non-volatile memory device is designed with rectifying portions composed of alternating first and second metal oxide layers, formed at a temperature of 600°C or lower using sputtering or atomic layer deposition, and resistance change portions made of chalcogenide compounds like Sb2Te3 and GeTe, allowing for reversible resistance state changes without significant crystal structure changes, thus maintaining the integrity of the resistance change material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon diode is used for rectifying element, then high ON/OFF ratio is achieved, but manufacturing process requires thermal treatment of 800°C or higher which deteriorates resistance change material
Solution Approach 1:
The patent changes the material parameter from silicon to metal oxide, which fundamentally alters the manufacturing temperature parameter from 800°C or higher to 600°C or lower, resolving the contradiction between achieving high ON/OFF ratio and avoiding deterioration of resistance change material
Solution Approach 2:
The rectifying element is constructed as a composite structure with first and second metal oxide layers having different band gaps, combining materials with complementary properties to achieve both high ON/OFF ratio and low-temperature compatibility
2Volume of moving object
If silicon diode size is reduced, then miniaturization is attempted, but there is a limit to reducing the size which becomes an obstacle to miniaturize the memory cell
Solution Approach 1:
The patent changes the material system from silicon to metal oxide, enabling further miniaturization by overcoming the physical size limits of silicon diodes while maintaining rectifying functionality through alternative material properties
Solution Approach 2:
The patent applies different metal oxide materials with specific local properties (band gap differences) to create the rectifying function, allowing miniaturization without relying on the size constraints of traditional silicon diode structures
3Ease of manufacture
If high-temperature process is used, then silicon diode rectifying element is manufactured, but characteristics of resistance change material are deteriorated
Solution Approach 1:
The patent changes the fabrication temperature parameter from high-temperature (800°C or higher) to low-temperature (600°C or lower) processing, enabling easy manufacture of rectifying elements while preserving the characteristics of resistance change material
Solution Approach 2:
The patent uses metal oxide materials that can be easily deposited at low temperatures through conventional techniques like sputtering, replacing the need for complex high-temperature silicon processing while achieving the desired rectifying functionality
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 enables the miniaturization of memory cells while maintaining high ON/OFF ratios, reducing power consumption, and improving data rewriting resistance, thereby enhancing the integration and cost-effectiveness of the memory device.
Implementation Method 1
The rectifying element acts to avoid data reading from an unselected memory cell and data writing thereto among plural memory cells that are connected in parallel. Thus, the rectifying element may preferably have a high ratio of a forward current to a backward current (ON/OFF ratio).
Implementation Method 2
resistance change portions made of chalcogenide compounds like Sb2Te3 and GeTe, allowing for reversible resistance state changes without significant crystal structure changes
Implementation Method 3
formed at a temperature of 600°C or lower using sputtering or atomic layer deposition
Implementation Method 4
formed at a temperature of 600°C or lower using sputtering or atomic layer deposition
Data Source
AI summary
According to an embodiment, a non-volatile memory device includes a first interconnection, a second interconnection closest to the first interconnection in a first direction, rectifying portions arranged in the first direction between the first interconnection and the second interconnection, and a first resistance change portion arranged between adjacent ones of the rectifying portions in the first direction. Each of the rectifying portions includes a first metal oxide layer and a second metal oxide layer.