Phase Change Memory Crystallization Accelerating Layer

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Solution Overview

Problem

Current semiconductor memory devices face challenges in performing high-speed write operations due to the lack of efficient crystallization acceleration and heat management in phase change memory cells, leading to longer times for set and reset operations.

Innovation Solution

Incorporating a crystallization accelerating layer with a cubic crystal structure, such as a sphalerite or face-centered cubic lattice structure, between the phase change layer and electrodes to control crystalline structure and heat distribution, reducing the heat quantity needed for melting and facilitating rapid crystallization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional phase change memory structure is used, then device simplicity is maintained, but write operation speed is slow due to lack of crystallization acceleration

Engineering Contradiction:

Improvewrite operation speedVSAvoidmemory cell structure

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent divides the phase change memory cell into distinct functional layers: a phase change layer containing Ge-Sb-Te alloy and a separate crystallization accelerating layer containing cubic crystal. This segmentation allows each layer to perform its specific function independently, with the cubic crystal layer providing dedicated crystallization acceleration without complicating the overall device structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cubic crystal layer acts as an intermediary between the heating element and the phase change material. It mediates the heat transfer process and provides a template for rapid crystallization of the Ge-Sb-Te alloy, enabling fast write operations without requiring complex heating mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If high heat quantity is applied for melting phase change layer, then complete phase transition is achieved, but operation time increases and energy consumption rises

Engineering Contradiction:

Improvephase transition completenessVSAvoidcrystallization time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent utilizes phase transitions of the Ge-Sb-Te alloy in conjunction with the cubic crystal structure. The cubic crystal layer facilitates rapid solidification from liquid to crystalline state after melting, enabling complete phase transition with controlled heat application and reducing the time required for crystallization.

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The patent changes the physical parameters of the system by introducing a cubic crystal layer with specific lattice structure (sphalerite or face-centered cubic). This structural parameter change enables faster heat dissipation and provides nucleation sites for rapid crystallization, reducing both time and energy requirements for complete phase transition.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If cubic crystal layer is added for crystallization acceleration, then write speed is enhanced, but manufacturing complexity increases

Engineering Contradiction:

Improveoperation speedVSAvoidlayer deposition process

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent specifies particular parameter ranges for the cubic crystal layer: thickness of 1-100 nm and composition containing Ge-Sb-Te alloy with specific ratios (Ge: 30-70 at%, Sb: 5-40 at%, Te: 20-50 at%). These parameter specifications enable standardized manufacturing processes while achieving the desired crystallization acceleration effect.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure combining the phase change layer (Ge-Sb-Te alloy) with a crystallization accelerating layer (cubic crystal). This composite material approach leverages the complementary properties of both materials to achieve rapid crystallization while maintaining compatibility with existing semiconductor manufacturing techniques.

Inventive Principle:

Principle #40Composite materials

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 enables faster set and reset operations by stabilizing the fcc lattice structure in the phase change layer, reducing the time for crystallization completion and enhancing the speed of write operations.

Implementation Method 1

The phase change layer contains a cubic crystal, wherein the first layer contains a crystal having a sphalerite structure or a face-centered cubic lattice structure

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 2

In order to perform a write operation, a heater 106 needs to melt a phase change layer 107

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11678593B2Semiconductor memory device with a phase change layer and particular heater material

Publication Date: 2023.06.13 KIOXIA CORP

AI summary

A semiconductor memory device includes a first electrode and a second electrode, a phase change layer disposed between the first electrode and the second electrode, and a first layer disposed between the first electrode and the phase change layer. The phase change layer contains at least one of germanium (Ge), antimony (Sb), and tellurium (Te). The first layer contains aluminum (Al) and antimony (Sb), or tellurium (Te) and at least one of zinc (Zn), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).