CBRAM Device Metal Bridge Formation via Composite Oxide Electrolyte

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Solution Overview

Problem

Conductive Bridging Random Access Memory (CBRAM) devices face challenges with low current density and reliability due to difficulties in adjusting oxygen vacancies in resistive random access memory (ReRAM) and maintaining stable resistance states.

Innovation Solution

A CBRAM device with a semiconductor oxide electrolyte layer having metal vacancies between electrodes, where the ratio and thickness of materials like CuO, Cu2O, NiOx, and TiOx are adjusted to form a metal bridge, allowing for high current density and improved data retention and endurance characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a solid electrolyte layer is formed between top and bottom electrodes to enable CBRAM operation, then nonvolatile memory behavior is achieved, but current density remains low due to difficulty in adjusting oxygen vacancies

Engineering Contradiction:

Improvedata retention and endurance characteristicsVSAvoidcurrent density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte layer by incorporating specific metal oxides (CuO, Cu2O, NiOx, TiOx, SnxO, CoxOy, ZnxO, AlxOy, IGZO) in controlled ratios to create metal vacancies. This compositional parameter change enables higher current density while maintaining nonvolatile memory characteristics through the formation of conductive metal bridges.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite oxide materials combining multiple metal oxides (e.g., CuO/Cu2O, NiOx/TiOx) in the electrolyte layer. This composite structure creates synergistic effects where different metal oxides contribute to forming metal vacancies and enabling ion transport, thereby achieving both high current density and reliable data retention.

Inventive Principle:

Principle #40Composite materials

2Reliability

If oxygen vacancies are adjusted in an oxide film to implement nonvolatile memory characteristics, then memory behavior is achieved, but conductivity remains low making current density insufficient

Engineering Contradiction:

Improvenonvolatile memory characteristicsVSAvoidcurrent density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent optimizes the oxygen vacancy concentration parameter by selecting specific metal oxide compositions and ratios. The presence of metal cations (Cu, Ni, Ti, Sn, Co, Zn, Al, In, Ga) in the electrolyte layer creates metal vacancies that serve as conduction pathways, changing the electrical conductivity parameter while maintaining nonvolatile memory behavior.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If a metal bridge is formed inside the solid electrolyte layer to increase current density, then high current density is achieved, but resistance state stability becomes difficult to maintain

Engineering Contradiction:

Improvecurrent densityVSAvoidresistance state stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent employs composite oxide electrolyte materials where multiple metal oxides work together to form a stable matrix. This composite structure provides structural stability while allowing controlled metal bridge formation. The different metal oxides create a balanced environment that maintains resistance state stability even with high current density operation.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent creates localized metal vacancies and metal bridge regions within the electrolyte layer while maintaining the overall stability of the oxide matrix. The metal bridges form in specific local regions where metal cations are available, while the surrounding oxide structure maintains structural integrity and resistance state stability.

Inventive Principle:

Principle #3Local quality

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

The solution achieves a current density of 2 MA/cm2 or greater, enhancing data retention and endurance by adjusting the metal vacancies through varying the material ratios, thickness, and heat treatment conditions, thereby stabilizing resistance states.

Implementation Method 1

allowing metal cations to be drifted into the solid electrolyte layer to form a metal bridge according to application of a positive voltage to the top electrode

Methodology Applied

Scientific EffectIon drift: Electrophoresis

Implementation Method 2

maintains a high resistance state by allowing a part of the metal bridge to be cut according to application of a negative voltage

Methodology Applied

Scientific EffectElectrochemical dissolution: Electrolysis

Implementation Method 3

heat-treating the semiconductor oxide electrolyte layer

Methodology Applied

Scientific EffectThermal annealing: Annealing

Data Source

PatentUS9831426B2CBRAM device and manufacturing method thereof

Publication Date: 2017.11.28 INDUSTRY UNIVERSITY COOPERATION FOUNDATION HANYANG UNIVERSITY

AI summary

Provided are a conductive bridging random access memory (CBRAM) device and a manufacturing method thereof. The CBRAM device includes a first electrode, a semiconductor oxide electrolyte layer formed on the first electrode and including a plurality of metal vacancies, a second electrode formed on the semiconductor oxide electrolyte layer, wherein when a positive voltage is applied to the second electrode, cations are reduced to the metal vacancies in the semiconductor oxide electrolyte layer to form a metal bridge.