Nonvolatile Memory Transistor with Ionic Species Moving Layer

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Solution Overview

Problem

Conventional flash memory devices face challenges with high operating voltage and limited multi-bit characteristics due to the small number of electrons trapped in floating gates, making it difficult to achieve low voltage and multi-level storage in small-sized nonvolatile memory devices.

Innovation Solution

The development of nonvolatile memory transistors with an ionic species moving layer, such as a bipolar memory layer or oxide layers like PrCaMnO, Ti oxide, and Ta oxide, between the gate insulation layer and the gate electrode, which allows for a change in threshold voltage through the movement of ionic species in response to applied voltage, enabling multi-level storage and low operating voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tunnel injection of electrons is used in conventional flash memory, then data storage is achieved, but operating voltage becomes high (10-20 V)

Engineering Contradiction:

Improvedata storage capabilityVSAvoidoperating voltage

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the storage mechanism from electron trapping in floating gate to ionic species movement in an oxide layer. This parameter change enables threshold voltage modulation through ion migration rather than electron tunneling, reducing operating voltage from 10-20V to much lower levels while maintaining nonvolatile memory functionality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the electrical tunneling mechanism with an ionic migration mechanism. Instead of using high-voltage electron tunneling through insulation layers, the system uses lower-voltage ionic species movement within the oxide layer to achieve threshold voltage changes, substituting one physical mechanism for another more efficient one

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If floating gate electron trapping is used, then nonvolatile storage is achieved, but multi-level characteristic is limited due to small number of trapped electrons

Engineering Contradiction:

Improvenonvolatile storageVSAvoidmulti-level characteristic

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes from discrete electron counting to continuous ionic concentration control. By modulating the concentration and position of ionic species in the oxide layer, the system achieves continuous threshold voltage adjustment, enabling multi-level storage capabilities that were not possible with discrete electron trapping in conventional floating gate devices

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The ionic species in the oxide layer serve as an intermediary between the control gate voltage and the channel current. This intermediary mechanism allows for gradual, continuous modulation of threshold voltage through ion migration, providing fine-grained control for multi-level storage rather than the binary on/off states of electron trapping

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If conventional flash memory structure is used, then nonvolatile memory function is achieved, but device size must be large to achieve sufficient electron trapping

Engineering Contradiction:

Improvenonvolatile memory functionVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The invention changes the storage mechanism to one that does not depend on trapping a large number of electrons in a large floating gate. Instead, ionic species movement in a thin oxide layer achieves threshold voltage modulation with much smaller device dimensions, as the effect depends on ion concentration and position rather than total electron count

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

These transistors achieve a multi-level characteristic of 16 levels or more with a low operating voltage range of ±5.0 V, overcoming the limitations of conventional flash memory by reducing the number of required transistors and simplifying circuit structures while enhancing reliability and reducing power consumption.

Implementation Method 1

a motion of an ionic species at the ionic species moving layer occurs according to a voltage applied to the gate electrode, wherein a threshold voltage changes according to the motion of the ionic species

Methodology Applied

Scientific EffectIonic species movement: Ion Exchange

Data Source

PatentUS9379319B2Nonvolatile memory transistor and device including the same

Publication Date: 2016.06.28 SAMSUNG ELECTRONICS CO LTD

AI summary

Provided are nonvolatile memory transistors and devices including the nonvolatile memory transistors. A nonvolatile memory transistor may include a channel element, a gate electrode corresponding to the channel element, a gate insulation layer between the channel element and the gate electrode, an ionic species moving layer between the gate insulation layer and the gate electrode, and a source and a drain separated from each other with respect to the channel element. A motion of an ionic species at the ionic species moving layer occurs according to a voltage applied to the gate electrode. A threshold voltage changes according to the motion of the ionic species. The nonvolatile memory transistor has a multi-level characteristic.