Nonvolatile Memory Cell Arrays with Vertical Stacking and Programmable Materials

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Solution Overview

Problem

Current nonvolatile memory cell technologies face challenges in achieving high density and efficient data storage due to limitations in programmable materials and electrode configurations, which affect the ability to reliably store and retrieve data in multiple resistive states without requiring frequent refresh.

Innovation Solution

The use of vertically stacked tiers of nonvolatile memory cells with programmable materials, such as ion conductive chalcogenides or metal oxides, sandwiched between conductive electrodes, allows for the creation of multiple resistive states by altering charge density distribution, enabling efficient data storage and retrieval without the need for frequent refresh.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If volatile memory is used for data storage, then data can be accessed quickly, but data must be refreshed multiple times per second to prevent dissipation

Engineering Contradiction:

Improvedata access speedVSAvoidrefresh energy consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent changes the fundamental parameter of memory cell state retention from transient (volatile) to persistent (nonvolatile) by utilizing programmable materials that maintain resistive states without refresh, thereby eliminating the need for periodic rewriting while maintaining data accessibility

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/electrical refresh mechanism required for volatile memory with a passive retention mechanism using programmable materials that inherently maintain their resistive state through material properties rather than active refresh cycles

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Quantity of substance

If the number of components in a memory cell is increased to enable multiple resistive states, then data storage capacity improves, but the device size increases

Engineering Contradiction:

Improvedata storage capacityVSAvoidmemory cell size

Core Design Contradiction:

Quantity of substanceVSVolume of moving object

Solution Approach 1:

The patent transitions from planar (2D) memory cell layouts to vertically stacked three-dimensional structures, allowing multiple memory cells to occupy the same footprint area by stacking them in the vertical dimension, thereby increasing storage density without expanding device area

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent employs composite material structures including programmable materials sandwiched between electrode layers in vertically stacked configurations, enabling multiple resistive states to be achieved through material composition and structure rather than increasing component count

Inventive Principle:

Principle #40Composite materials

3Reliability

If programmable materials are used that require ion transport to change resistive states, then nonvolatile storage is achieved, but the programming process becomes more complex

Engineering Contradiction:

Improvedata retention without refreshVSAvoidprogramming mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent utilizes changes in ionic concentration and charge density distribution within programmable materials as the fundamental mechanism for achieving resistive state transitions, leveraging material parameter changes rather than complex mechanical or electrical switching mechanisms

Inventive Principle:

Principle #35Parameter changes

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 configuration enhances data storage density and reliability by allowing reversible transitions between high and low resistance states, improving the overall performance and efficiency of nonvolatile memory cells.

Implementation Method 1

The programmable materials may be converted from one memory state to another by moving the mobile charge carriers therein to alter a distribution of charge density within the programmable materials

Methodology Applied

Scientific EffectIon transport: Ion Exchange

Implementation Method 2

A suitable voltage applied across the electrodes generates current conductive super-ionic clusters or filaments

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS9620174B2Arrays of nonvolatile memory cells comprising a repetition of a unit cell, arrays of nonvolatile memory cells comprising a combination of vertically oriented and horizontally oriented memory cells, and arrays of vertically stacked tiers of nonvolatile memory cells

Publication Date: 2017.04.11 MICRON TECHNOLOGY INC

AI summary

Disclosed is an array of nonvolatile memory cells includes five memory cells per unit cell. Also disclosed is an array of vertically stacked tiers of nonvolatile memory cells that includes five memory cells occupying a continuous horizontal area of 4F2 within an individual of the tiers. Also disclosed is an array of nonvolatile memory cells comprising a plurality of unit cells which individually comprise three elevational regions of programmable material, the three elevational regions comprising the programmable material of at least three different memory cells of the unit cell. Also disclosed is an array of vertically stacked tiers of nonvolatile memory cells that includes a continuous volume having a combination of a plurality of vertically oriented memory cells and a plurality of horizontally oriented memory cells. Other embodiments and aspects are disclosed.