Parallel Resistive Memory Cell for Low Resistance and Variability

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Solution Overview

Problem

Volatile memory elements in integrated circuits are prone to soft error upsets due to cosmic rays and radioactive impurities, leading to data loss, and traditional non-volatile resistive memory elements require high current for operation and exhibit large variation across memory cells.

Innovation Solution

The implementation of memory cells with resistive memory elements formed in integrated circuits, where multiple resistive memory elements are connected in parallel, reducing the on-state resistance and variability, and using a specific structure with metal layers and oxide layers to achieve lower and more consistent resistive states for data storage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If traditional non-volatile resistive memory elements are used, then data retention without power is achieved, but high current is required for operation and large variation across memory cells occurs

Engineering Contradiction:
Improvedata retention timeVSAvoidoperational current
Core Design Contradiction:
Duration of action of stationary objectVSUse of energy by moving object

Solution Approach 1:

The patent divides a single resistive memory element into multiple parallel resistive memory elements (e.g., four elements in parallel). This segmentation reduces the on-state resistance of the overall memory cell while maintaining non-volatile data retention, thereby lowering the current requirement for operation without sacrificing data retention capability.

Inventive Principle:
Principle #1Segmentation

2Duration of action of stationary object

If traditional non-volatile resistive memory elements are used, then data retention without power is achieved, but large variation across memory cells occurs

Engineering Contradiction:
Improvedata retention timeVSAvoidmemory cell resistance consistency
Core Design Contradiction:
Duration of action of stationary objectVSManufacturing precision

Solution Approach 1:

By implementing multiple parallel resistive memory elements, the patent reduces the impact of individual element variations on the overall cell performance. The parallel configuration averages out the resistance variations, leading to more consistent on-state resistance across different memory cells while preserving non-volatile data retention.

Inventive Principle:
Principle #1Segmentation

3Speed

If volatile memory elements are used, then fast operation is achieved, but soft error upsets occur and data is lost on power loss

Engineering Contradiction:
Improveoperation speedVSAvoiddata retention reliability
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent uses multiple parallel resistive memory elements to achieve a configuration that combines advantages of both volatile and non-volatile memory. The parallel structure reduces on-state resistance for faster operation while the non-volatile nature of resistive memory elements ensures data retention without power and resistance to soft error upsets.

Inventive Principle:
Principle #1Segmentation

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 solution enhances the resistance of integrated circuit memory arrays to soft error upsets and reduces the operational current requirements, resulting in a more reliable and stable data storage system with lower on-state resistance variability.

Implementation Method 1

resistive switching memory units made of chalcogenide or metal oxide

Methodology Applied
Scientific EffectResistive switching: Electrical Resistance

Data Source

PatentEP3267502B1Memory cell with parallel resistive memory elements
Publication Date: 2020.09.30 ALTERA CORP
  • EP3267502B1 patent drawingFigure 1
  • EP3267502B1 patent drawingFigure 2
  • EP3267502B1 patent drawingFigure 3A

AI summary

A memory cell (208) is disclosed that includes at least two non-volatile resistive memory elements (302) coupled in parallel, preferably via first and second metal layers (304, 306), one of which may be connected to a source-drain region (312) of an access transistor (214). The non-volatile resistive memory elements are capable of existing in different resistive states such that each of the different resistive state represents a different data state. The parallel connection leads to a mean on-state resistance which is lower and less variable.