Nonvolatile Memory Cell With Diode Steering Element
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Solution Overview
Problem
Existing nonvolatile memory devices face challenges in creating erasable or multi-state memory cells using conventional semiconductor materials, as they are difficult to scale to small sizes and operate efficiently, especially with complex structures like floating gate and SONOS cells, and exotic materials like chalcogenides present production challenges.
Innovation Solution
A nonvolatile memory device is formed using a semiconductor diode steering element and a semiconductor resistor read/write switching element, arranged in series with conductive layers, allowing for two or more stable resistivity states to be achieved through appropriate electrical pulses, reducing leakage current and enabling dense cross-point memory arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If floating gate and SONOS memory cells are used to achieve erasable or multi-state cells, then data storage capability is improved, but device complexity and fabrication difficulty increase
Solution Approach 1:
The memory cell is divided into two separate terminals: a first terminal for programming/erasing operations and a second terminal for read operations. This segmentation allows independent optimization of programming and read functions, simplifying the overall device structure while maintaining erasable and multi-state capabilities without requiring complex floating gate or SONOS structures
Solution Approach 2:
The patent extracts the complex charge storage mechanisms from floating gate and SONOS structures and replaces them with a simpler resistive switching element. This extraction eliminates the need for complex multi-layer gate structures while preserving the essential functionality of erasable and multi-state memory operation
2Adaptability or versatility
If chalcogenide materials are used to achieve resistivity changes for data storage, then data state capability is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent uses conventional semiconductor materials and changes their resistivity parameter through electrical field-induced phase transitions in the resistive switching element. This approach achieves multiple stable resistivity states using standard semiconductor fabrication processes, avoiding the need to work with difficult-to-process chalcogenide materials while maintaining the desired multi-state capability
Solution Approach 2:
The patent replaces expensive and difficult-to-manufacture chalcogenide materials with conventional, inexpensive semiconductor materials that can be processed using standard fabrication techniques. This substitution maintains the functional capability of resistivity switching while dramatically improving manufacturability and compatibility with existing production facilities
3Productivity
If memory cells are scaled to small dimensions for competitiveness, then integration density is improved, but leakage current increases
Solution Approach 1:
The memory cell is segmented into separate programming and read terminals, allowing the read operation to be performed at low voltages that do not induce leakage. The programming terminal handles high-voltage operations independently, preventing leakage current from affecting the read functionality and enabling safe scaling to small dimensions
Solution Approach 2:
The patent introduces a diode element as an intermediary between the programming and read functions. This diode acts as a steering element that directs current flow during programming operations while blocking leakage paths during read operations, enabling the memory cell to be scaled down without suffering from increased leakage current
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 configuration allows for the creation of memory cells with reduced leakage current, enabling efficient data storage in a highly dense array, with the ability to switch between multiple data states, making the memory cells either one-time-programmable or rewriteable, using conventional semiconductor materials.
Implementation Method 1
a read/write switching element, which in this example is a semiconductor resistor, capable of achieving two or more stable resistivity states through appropriate electrical pulses
Data Source
AI summary
A method of making a nonvolatile memory device includes forming a semiconductor diode steering element, and forming a semiconductor read/write switching element.