GeTe Superlattice Memory with Sb2Te3:N Diffusion Barrier

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Solution Overview

Problem

Cross-point type memory devices using superlattice memory face limitations in the number of times data can be rewritten due to Ge atom diffusion, leading to reduced durability and functionality.

Innovation Solution

Incorporating an Sb2Te3:N layer between Sb2Te3 and GeTe layers in the superlattice structure, which prevents Ge atom diffusion, thereby increasing the number of rewriting cycles and enhancing the crystallizability of the superlattice structure without requiring new targets or complex manufacturing processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a conventional superlattice structure with GeTe and Sb2Te3 layers is used, then low power consumption is achieved, but the number of rewriting cycles is limited due to Ge atom diffusion

Engineering Contradiction:

Improvepower consumptionVSAvoidnumber of rewriting cycles

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

An Sb2Te3:N layer is introduced as an intermediary barrier layer between the GeTe layer and the Sb2Te3 layer. This intermediate layer prevents Ge atoms from diffusing into the Sb2Te3 layer while maintaining the low power consumption characteristics of the original superlattice structure. The nitrogen doping in Sb2Te3 creates a diffusion barrier that resolves the contradiction between maintaining low power consumption and increasing rewriting durability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses a composite material approach by combining Sb2Te3 with nitrogen doping to create Sb2Te3:N. This composite material serves dual purposes: it maintains the structural integrity of the superlattice while providing a diffusion barrier against Ge atoms. The composite material enables both low power consumption and increased rewriting cycles by preventing Ge diffusion.

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If Ge atoms are allowed to diffuse in the layered crystal, then resistance switching is enabled, but the durability for repeated rewriting is reduced

Engineering Contradiction:

Improveresistance switching capabilityVSAvoiddurability for repeated rewriting

Core Design Contradiction:

Ease of operationVSDuration of action of stationary object

Solution Approach 1:

The patent segments the Sb2Te3 layer into two parts: an Sb2Te3:N layer (diffusion barrier) and a regular Sb2Te3 layer (resistance switching region). This segmentation allows Ge atoms to diffuse in the regular Sb2Te3 layer for resistance switching while the Sb2Te3:N layer prevents excessive diffusion that would degrade durability. The segmentation resolves the contradiction between enabling resistance switching and maintaining rewriting durability.

Inventive Principle:

Principle #1Segmentation

3Reliability

If nitrogen is added to Sb2Te3 to prevent Ge diffusion, then rewriting cycles increase, but manufacturing complexity may increase

Engineering Contradiction:

Improvenumber of rewriting cyclesVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the chemical composition parameter of Sb2Te3 by adding nitrogen to create Sb2Te3:N. This parameter change (nitrogen doping) modifies the material properties to prevent Ge diffusion, thereby increasing rewriting cycles. The manufacturing process uses conventional sputtering with nitrogen-containing gas, which adds minimal complexity to existing fabrication processes.

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

The Sb2Te3:N layer effectively prevents Ge atom diffusion, significantly increasing the number of rewriting cycles and maintaining the crystallizability of the superlattice structure, thus improving the memory device's durability and performance.

Implementation Method 1

Incorporating an Sb2Te3:N layer between Sb2Te3 and GeTe layers in the superlattice structure, which prevents Ge atom diffusion

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

the resistance value thereof can be changed by the movement of Ge atoms in the layered crystal

Methodology Applied

Scientific EffectAtomic migration: Diffusion

Implementation Method 3

maintaining the crystallizability of the superlattice structure

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS10283707B2Superlattice memory having GeTe layer and nitrogen-doped Sb<sub>2</sub>Te<sub>3 </sub>layer and memory device having the same

Publication Date: 2019.05.07 KIOXIA CORP

AI summary

According to one embodiment, a superlattice memory comprises substrate, a first electrode provided on the substrate, a second electrode arranged in opposition to the first electrode, and a superlattice structure part provided between the first electrode and the second electrode, which includes first chalcogen compound layers, second chalcogen compound layers the composition of which is different from the first chalcogen compound, and contains Ge, and third chalcogen compound layers in which one of N, B, C, O, and F is added to the first chalcogen compound, stacked one on another.