Phase-Change Material Layer Tellurium Control Sputtering

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Solution Overview

Problem

Conventional methods for forming phase-change material layers in PRAM devices, such as those using GST, face challenges in controlling the composition ratio, particularly in reducing tellurium content below 50% by weight, which affects the electrical characteristics and crystallization of the material.

Innovation Solution

A sputtering process is employed at a temperature where tellurium is volatilized and antimony is not, using a chalcogenide target with germanium, antimony, and tellurium, to form a phase-change material layer with a chalcogenide material having 5 to 50% by weight tellurium, ensuring improved electrical characteristics and desirable crystallization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a PVD process such as sputtering is used to form a phase-change material layer, then the layer can be deposited, but controlling the composition ratio of GST becomes difficult and tellurium content cannot be reduced below 50% by weight

Engineering Contradiction:

Improvecomposition ratio controlVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by controlling the substrate temperature during sputtering to a specific range (room temperature to 150°C) to enable selective volatilization of tellurium. This temperature parameter control allows the process to achieve tellurium content below 50% by weight while maintaining stable deposition, resolving the contradiction between composition precision and process ease.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs preliminary action by pre-heating the substrate to a controlled temperature before and during the sputtering process. This preliminary temperature preparation creates conditions for selective tellurium volatilization during deposition, enabling precise composition control without requiring complex post-processing or advanced equipment.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If tellurium content is reduced below 50% by weight in the phase-change material layer, then electrical characteristics improve, but conventional sputtering processes cannot achieve this composition ratio

Engineering Contradiction:

Improveelectrical characteristicsVSAvoidcomposition ratio control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the temperature parameter during sputtering to enable selective tellurium removal. By maintaining substrate temperature between room temperature and 150°C, the process achieves tellurium content below 50% by weight, thereby improving electrical characteristics such as resistance ratio between amorphous and crystalline states while maintaining manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the typically harmful effect of tellurium (which degrades electrical performance when present in high amounts) into a benefit by selectively volatilizing excess tellurium during deposition. This controlled loss of tellurium through selective volatilization improves the electrical characteristics of the phase-change material layer.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If conventional sputtering is used without temperature control, then the process is simpler, but the phase-change material layer does not achieve desirable crystallization characteristics

Engineering Contradiction:

Improvecrystallization characteristicsVSAvoidprocess control requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces temperature control as a critical parameter during sputtering, maintaining substrate temperature between room temperature and 150°C. This parameter change enables desirable crystallization characteristics in the phase-change material layer without requiring complex multi-step processes or advanced equipment, achieving reliable crystallization with moderate process control.

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 process effectively forms phase-change material layers with enhanced electrical properties and improved crystallization characteristics, enabling the production of phase-change memory devices with increased reliability and endurance.

Implementation Method 1

performing a sputtering process to form the phase-change material layer including a chalcogenide material on the substrate

Methodology Applied

Scientific EffectSputtering: Sputtering

Implementation Method 2

tellurium is volatilized and antimony is not volatilized... volatilizing at least some portions of tellurium included in the preliminary chalcogenide material

Methodology Applied

Scientific EffectVolatilization: Evaporation

Data Source

PatentUS8192592B2Methods of forming a phase-change material layer including tellurium and methods of manufacturing a phase-change memory device using the same

Publication Date: 2012.06.05 SAMSUNG ELECTRONICS CO LTD

AI summary

The present invention provides methods of forming a phase-change material layer including providing a substrate and a chalcogenide target including germanium (Ge), antimony (Sb) and tellurium (Te) at a temperature wherein tellurium is volatilized and antimony is not volatilized, and performing a sputtering process to form the phase-change material layer including a chalcogenide material on the substrate. Methods of manufacturing a phase-change memory device using the same are also provided.