SiCr Resistor Non-Volatile Memory High Temperature Reliability
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Solution Overview
Problem
Existing non-volatile re-programmable memory devices face challenges in maintaining data integrity at elevated temperatures due to charge leakage in charge-based memories and low phase change temperatures in phase change memories, limiting their environmental usability.
Innovation Solution
A re-programmable non-volatile memory device utilizing a SiCr-based resistor that changes resistance states through SiCr-facilitated migration, driven by electrical-field or electromigration, allowing for reversible resistive states and high thermal-activation energy, enabling reliable data storage at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge-based memory is used, then data storage capability is achieved, but charge leakage occurs at elevated temperatures leading to data loss
Solution Approach 1:
The patent changes the fundamental operating parameter from charge storage to resistance state storage. The SiCr resistor exhibits reversible resistance changes through electromigration of chromium atoms, where write current causes Cr migration to one end and erase current causes migration to the other end. This resistance-based mechanism is inherently stable at elevated temperatures unlike charge-based mechanisms, directly resolving the temperature-dependent reliability issue.
Solution Approach 2:
The patent replaces the electrical charge storage mechanism with a physical material migration mechanism. Instead of relying on trapped charges that leak at high temperatures, the system uses electromigration-driven movement of chromium atoms within the SiCr resistor lattice. This mechanical/physical migration process creates stable resistance states that are maintained even at elevated temperatures, eliminating the charge leakage problem.
2Reliability
If phase change memory with low melting point materials is used, then non-volatile storage is achieved, but data retention fails at elevated temperatures
Solution Approach 1:
The patent fundamentally changes the storage mechanism from phase change (solid-liquid transition) to resistance state change via electromigration. The SiCr resistor maintains distinct high and low resistance states through controlled chromium atom migration, without requiring phase transitions. This eliminates the temperature sensitivity inherent in low-melting-point phase change materials, enabling reliable data retention at elevated temperatures where phase change materials would lose their structural integrity.
Solution Approach 2:
The patent uses a composite SiCr (Silicon-Chromium) material system where silicon provides a stable crystalline lattice structure and chromium provides the migratory atoms necessary for resistance switching. This composite structure combines the thermal stability of silicon with the electromigration properties of chromium, creating a material that maintains stable resistance states at high temperatures without requiring low-melting-point phase change materials.
3Reliability
If multiple transistors per memory cell are used, then re-programmable non-volatile memory functionality is achieved, but device size reduction is limited
Solution Approach 1:
The patent extracts the complex multi-transistor control logic from the memory cell itself and relocates it to external control circuitry. The memory cell is reduced to its essential function: a single SiCr resistor that changes resistance state in response to externally applied write and erase currents. This extraction of control functionality enables extreme miniaturization of the memory cell while maintaining full re-programmable non-volatile memory capabilities through sophisticated external control.
Solution Approach 2:
The patent creates a universal memory cell structure where a single SiCr resistor can serve as the storage element for multiple memory functions. The same basic cell structure supports write, erase, and read operations through different current applications, and can be integrated into various memory architectures (SRAM, DRAM, Flash). This multi-functionality reduces the need for specialized transistors and control circuits within each cell type, enabling size reduction while maintaining versatile memory 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
The SiCr-based memory device maintains resistance states and data integrity at temperatures above 300°C, providing heat and radiation resistance, and allows for high-density memory integration with various semiconductor technologies.
Implementation Method 1
SiCr-facilitated migration refers to electrical-field driven migration and/or electromigration, wherein at least one element, possibly other than electromigration ions, migrates along the SiCr resistor
Implementation Method 2
SiCr-facilitated migration refers to electrical-field driven migration and/or electromigration, wherein at least one element, possibly other than electromigration ions, migrates along the SiCr resistor
Implementation Method 3
In certain embodiments the thermal-activation energy of the SiCr-facilitated migration process is high, for example around 2.5 eV
Data Source
AI summary
A memory device including a non-volatile re-programmable memory cell is provided. In connection with various example embodiments, the memory cell is a single resistor located between a first and second node. The resistor stores different resistance states corresponding to different resistance values set by SiCr-facilitated migration. The SiCr-facilitated migration occurs in response to energy presented between the first and second nodes. The application of a signal to a first node of the memory cell resistor forces the migration of elements along the memory cell resistor to set the resistance value of the memory cell resistor. The application of a second signal of approximately equal strength to the second node reverses the change and resistance and returns the memory cell to the previous resistance level. In some implementations the resistor is made of SiCr.