Reversible Resistance Memory Programming via Bidirectional Voltage Adjustment

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Solution Overview

Problem

Existing methods for programming nonvolatile memory devices, such as flash memory and resistance-change memory devices, face challenges in efficiently writing and storing signal information due to limitations in changing electrical resistance states, particularly in multi-level resistance storage.

Innovation Solution

A method for programming nonvolatile memory devices that involves selecting a target memory cell with a reversible resistance device, determining and comparing its resistance state to a target state, and performing either a positive or negative program operation by applying specific voltages to adjust the resistance, allowing for reliable storage of different electrical resistance states without the need for separate erase operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate erase operations are performed before programming in flash memory devices, then reliable data storage is achieved, but programming speed and operational efficiency deteriorate

Engineering Contradiction:

Improvedata storage reliabilityVSAvoidprogramming speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The invention extracts and eliminates the separate erase operation from the programming process by utilizing the reversible resistance device's inherent ability to switch between resistance states directly, thereby removing the bottleneck step while maintaining data storage reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of following the conventional sequence of erase-then-program, the invention inverts the approach by directly programming the resistance state without prior erasure, leveraging the reversible resistance device's capability to be set to desired states directly

Inventive Principle:

Principle #13The other way round (Inversion)

2Quantity of substance

If multiple resistance states are used for multi-level storage, then storage capacity increases, but control precision and reliability deteriorate

Engineering Contradiction:

Improvestorage capacityVSAvoidresistance state control precision

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The invention implements feedback mechanisms through verification operations that read the resistance state after programming, compare it with the target state, and apply corrective voltages if necessary, thereby maintaining high control precision even when using multiple resistance states for increased storage capacity

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The invention applies partial programming actions with intermediate verification steps rather than attempting to set all resistance states in a single operation, allowing precise control over each transition while building up multi-level storage states incrementally

Inventive Principle:

Principle #16Partial or excessive action

3Ease of operation

If simple program operations are used in resistance-change memory devices, then operational complexity decreases, but programming reliability and precision deteriorate

Engineering Contradiction:

Improveoperational simplicityVSAvoidprogramming reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The invention performs preliminary verification operations after programming attempts to detect whether the resistance state was successfully set, and if not, applies additional corrective programming actions to ensure reliable state achievement while maintaining operational simplicity

Inventive Principle:

Principle #10Preliminary action

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 precise control over signal information storage, improving programming speed and storage capacity by directly converting resistance states without requiring separate erase operations, thus enhancing the efficiency of signal information writing in nonvolatile memory devices.

Implementation Method 1

A target resistance state for the reversible resistance device of the target memory cell may be determined. A resistance state of the reversible resistance device of the target memory cell may be read. The read resistance state may be compared with the target resistance state. One of a positive program operation and a negative program operation may be performed for the reversible resistance device of the target memory cell

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentUS11527290B2Method of programming nonvolatile memory device including reversible resistance device

Publication Date: 2022.12.13 SK HYNIX INC

AI summary

A method of programming a nonvolatile memory device including a plurality of memory cells is provided. Each of the plurality of memory cells includes a reversible resistance device. A target memory cell is selected from among the plurality of memory cells. A target resistance state for the reversible resistance device of the target memory cell is determined. A resistance state of the reversible resistance device of the target memory cell is read. The read resistance state is compared with the target resistance state. One of a positive program operation and a negative program operation is performed for the reversible resistance device of the target memory cell when the read resistance state is different from the target resistance state.