Ferroelectric Memory Cell Volatile Nonvolatile Mode Switching
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Solution Overview
Problem
Current memory technologies face challenges in achieving high memory speed and endurance while maintaining nonvolatility, as existing volatile memories are prone to data loss when power is switched off, and nonvolatile memories suffer from low speed and manufacturability issues.
Innovation Solution
A memory cell utilizing a ferroelectric material that operates in both volatile and nonvolatile modes, with the nonvolatile mode activated by increasing the operating voltage to exceed the electric coercive field strength of the ferroelectric material, allowing for long-term data storage without additional nonvolatile memory elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional nonvolatile memory elements are added to conventional volatile memories to achieve nonvolatility, then data persistence is improved, but memory density and device complexity deteriorate enormously
Solution Approach 1:
The ferroelectric capacitor serves dual functions: as a volatile storage element during normal operation and as a nonvolatile storage element when high voltage is applied. This multi-functionality eliminates the need for separate volatile and nonvolatile memory structures, thereby improving memory density while maintaining data persistence capability.
Solution Approach 2:
The invention changes the voltage parameter to switch between volatile and nonvolatile operating modes. By applying high voltage exceeding the coercive field strength, the ferroelectric material transitions to a nonvolatile state; by operating at lower voltages, it functions as a volatile memory, thus achieving both modes with a single structure.
2Reliability
If additional nonvolatile memory elements and circuitry are incorporated to achieve nonvolatility, then data persistence is improved, but manufacturing complexity and process steps increase
Solution Approach 1:
The same ferroelectric capacitor structure is used for both volatile and nonvolatile operation, eliminating the need for additional memory elements and associated manufacturing processes. This reduces fabrication complexity while maintaining data persistence through mode switching.
Solution Approach 2:
The invention merges volatile and nonvolatile memory functions into a single integrated structure. The ferroelectric capacitor combines the benefits of both memory types without requiring separate fabrication processes for distinct memory elements, thereby simplifying manufacturing.
3Reliability
If high voltage is applied to exceed the electric coercive field strength of the ferroelectric material, then nonvolatile storage is achieved, but energy consumption increases
Solution Approach 1:
High voltage is applied periodically or only when needed to switch the ferroelectric material into the nonvolatile state. During normal volatile operation, lower voltages are used, thus reducing overall energy consumption while still achieving nonvolatile storage capability when required.
Solution Approach 2:
The system proactively switches to nonvolatile mode before power loss occurs by detecting power supply anomalies and applying high voltage in advance. This preliminary action ensures data persistence without requiring continuous high voltage, thereby managing energy consumption effectively.
4Speed
If the memory operates in volatile mode for high speed, then operating speed is improved, but data persistence is lost when power is switched off
Solution Approach 1:
The memory dynamically switches between volatile and nonvolatile operating modes based on operational requirements. During normal operation, it functions as high-speed volatile memory; upon detecting power supply issues, it transitions to nonvolatile mode to preserve data, thus achieving both speed and persistence.
Solution Approach 2:
The operating voltage parameter is changed to switch between modes: lower voltages enable high-speed volatile operation, while high voltage exceeding the coercive field strength enables nonvolatile storage. This parameter change allows the system to optimize for either speed or persistence as needed.
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 high-speed and long-endurance memory operations while ensuring data persistence across power supply disruptions, balancing the advantages of volatile and nonvolatile storage without compromising manufacturability.
Implementation Method 1
an information storage element (12) which comprises a ferroelectric material
Implementation Method 2
the operating voltage across the information storage element in the nonvolatile operating mode results in a saturated polarization hysteresis and in the volatile operating mode only in an unsaturated polarization hysteresis
Implementation Method 3
an operating voltage across the information storage element that is increased with respect to the volatile operating mode, such that in the nonvolatile operating mode, an electric coercive field strength of the ferroelectric material is exceeded
Data Source
AI summary
Nonvolatile storage with long memory endurance having the advantages of easy manufacturability is obtained by using a memory cell having an information storage element including a ferroelectric material, and operating the memory cell in a volatile operating mode and a nonvolatile operating mode. The option of operating the memory cell in the volatile operating mode enables the associated advantages of high memory speed at long endurance, wherein, however, the option of operating the memory cell in the nonvolatile operating mode can bridge gaps in the power supply.