Correlated Electron Switch Memory for High-Density Low-Power Operations
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Solution Overview
Problem
Current non-volatile memory technologies face challenges in achieving low power, high speed, high density, and stability, particularly in scaling below 65 nanometers, with existing resistance switching mechanisms being unsuitable due to instability, high currents, and temperature dependence.
Innovation Solution
A correlated electron switch (CES) device utilizing a Mott transition between conductive and insulative states, controlled by electron concentration and applied voltages and currents, allowing for deterministic, low-power, high-speed, and high-density memory operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If flash memory devices are used to achieve high density and scalability, then memory density and scalability are improved, but write/erase speed and power consumption worsen due to the need for high voltages and long operation times
Solution Approach 1:
The patent changes the fundamental operating parameter from voltage-based switching (flash memory) to current-based switching (racetrack memory). By using spin-polarized current to induce magnetization reversal via spin transfer torque, the system achieves fast write operations without requiring high voltages, thus resolving the contradiction between density and speed.
Solution Approach 2:
The patent replaces the mechanical/electrical field-based switching mechanism of flash memory with a quantum mechanical spin-based mechanism. The spin transfer torque effect allows for rapid magnetization reversal without the need for high voltage fields, enabling faster write operations while maintaining high density through vertical bit stacking.
2Reliability
If EEPROM devices are used to achieve non-volatile storage, then data retention is improved, but write/erase time and power consumption worsen due to requiring tens of microseconds and high voltages
Solution Approach 1:
The patent changes the switching mechanism from voltage-controlled charge trapping (EEPROM) to current-controlled spin transfer torque. This allows write operations to occur in nanoseconds rather than microseconds, dramatically reducing operation time while maintaining non-volatile data retention through stable magnetization states.
Solution Approach 2:
The patent employs periodic alternating current (AC) signals to write data to the racetrack memory. The alternating current reverses direction periodically, enabling controlled magnetization reversal at specific locations along the nanowire by adjusting the frequency and phase,从而实现 fast and precise write operations.
3Productivity
If phase change memory is used to achieve variable resistance, then memory state switching is improved, but stability and controllability worsen due to dependence on melting and solidification processes
Solution Approach 1:
The patent replaces the thermal melting/solidification mechanism of phase change memory with a spin transfer torque mechanism. Instead of relying on uncontrolled phase transitions that require high temperatures, the system uses spin-polarized current to induce deterministic magnetization reversal, achieving both fast switching and stable, controllable memory states.
4Productivity
If resistive RAM is used to achieve variable resistance switching, then memory operation speed is improved, but reliability worsens due to stochastic behavior and temperature dependence
Solution Approach 1:
The patent replaces the stochastic filament formation mechanism of resistive RAM with a deterministic spin transfer torque mechanism. The spin-polarized current provides controlled magnetization reversal through quantum mechanical effects, eliminating random behavior and temperature dependence while maintaining fast operation speeds.
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 CES device provides stable and scalable memory solutions by enabling abrupt conductor/insulator transitions through quantum mechanical phenomena, overcoming the limitations of existing technologies in terms of endurance, power consumption, and scalability.
Implementation Method 1
A correlated electron switch (CES) device utilizing a Mott transition between conductive and insulative states
Data Source
AI summary
Disclosed are methods, systems and devices for operation of correlated electron switch (CES) devices. In one aspect, a CES device may be placed in any one of multiple impedance states in a write operation by controlling a current and a voltage applied to terminals of the non-volatile memory device. In one implementation, a CES device may be placed in a high impedance or insulative state, or two more distinguishable low impedance or conductive states.