Ferroelectric Transistor Static RAM Cell for Non-Volatile Storage

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Solution Overview

Problem

Existing electronic data storage techniques face challenges in maintaining non-volatile storage of logic states during power-down events, leading to data loss and increased complexity and costs in scaling semiconductor devices.

Innovation Solution

Incorporating a non-volatile storage element, such as a ferroelectric transistor, into a static storage cell structure that allows for volatile write and read operations at low latency, enabling non-volatile storage of logic states during power-down and re-establishment upon power-up without additional overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If flash memories are used for non-volatile storage, then data retention during power-down is improved, but access speed deteriorates and device complexity increases

Engineering Contradiction:
Improvedata retentionVSAvoidaccess speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The patent applies dynamics by enabling the storage system to switch between two operational modes: volatile mode for high-speed access during power-on, and non-volatile mode for data retention during power-down. The system dynamically adapts its behavior based on power state, combining the speed of volatile memory with the retention capability of non-volatile memory without sacrificing access performance during active operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements multi-functionality by designing a storage system that can operate in both volatile and non-volatile modes using the same hardware infrastructure. The storage device universally handles both high-speed volatile storage and energy-retentive non-volatile storage, eliminating the need for separate storage systems and reducing overall device complexity while maintaining both speed and reliability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If floating gate-type storage transistors are used, then non-volatile storage capability is improved, but manufacturing complexity and costs increase

Engineering Contradiction:
Improvenon-volatile storage capabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the non-volatile storage functionality directly into the existing CMOS transistor structure by integrating a non-volatile storage element (such as a ferroelectric transistor) as part of the standard logic circuitry. This combination allows the storage function to be embedded within the logic device itself, reducing the need for separate floating gate structures and simplifying the manufacturing process while maintaining non-volatile capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent applies parameter changes by modifying the electrical characteristics of standard transistors through the integration of non-volatile materials (e.g., ferroelectric materials in the gate dielectric). This changes the transistor's behavior to retain state information without requiring the complex floating gate electrode structures, thereby reducing manufacturing complexity while achieving non-volatile storage capability.

Inventive Principle:
Principle #35Parameter changes

3Speed

If static memory structures are used, then access speed is improved, but data retention during power-down deteriorates

Engineering Contradiction:
Improveaccess speedVSAvoiddata retention
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent applies dynamics by enabling the storage system to switch between two operational modes: volatile mode for high-speed access during power-on, and non-volatile mode for data retention during power-down. The system dynamically adapts its behavior based on power state, combining the speed of volatile memory with the retention capability of non-volatile memory without sacrificing access performance during active operation.

Inventive Principle:
Principle #15Dynamics

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 allows for seamless operation by maintaining logic states across power cycles, reducing electronic overhead and complexity, and enabling efficient non-volatile storage without compromising standard read and write capabilities.

Implementation Method 1

In other approaches, the ferroelectric effect has been exploited so as to provide circuit elements, such as resistors, transistors and the like, in which a ferroelectric material may be polarized in order to appropriately affect the operational behavior.

Methodology Applied
Scientific EffectFerroelectric effect:

Data Source

PatentUS9966128B1Storage structure with non-volatile storage capability and a method of operating the same
Publication Date: 2018.05.08 GLOBALFOUNDRIES US INC

AI summary

The present disclosure provides a storage cell or storage structure having a static RAM-like operational behavior while nevertheless providing non-volatile storage capability on a single bit basis. To this end, a non-volatile storage element, such as a ferroelectric transistor element, may be provided within an inverter structure so as to allow the storage of a logic state at any desired operational phase by increasing the voltage difference used for operating the inverter structure. In illustrative embodiments, the stored logic state may be re-established during a power-up event.