GeSbTe ALD Stoichiometry Control via Segmented Precursor Cycles

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Solution Overview

Problem

Conventional atomic layer deposition (ALD) processes for GeSbTe materials are limited in stoichiometry, only allowing compositions on the GeTe or Sb2Te3 tie-lines, making it difficult to deposit these materials in small semiconductor device structures and limiting the achievable stoichiometries of GeSbTe materials.

Innovation Solution

The method involves using reactive and co-reactive metal precursors in ALD layer cycles to form GeSbTe materials with desired stoichiometries by adjusting the number of germanium, antimony, and tellurium layers, allowing for compositions off the tie-line, and depositing these materials in small openings with high conformality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional ALD processes are used to deposit GeSbTe materials, then highly conformal layers can be deposited in small openings or vias, but the composition is limited to only GeTe or Sb2Te3 tie-line stoichiometries

Engineering Contradiction:

Improveconformality of deposited layerVSAvoidrange of achievable stoichiometries

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent segments the deposition process into multiple ALD cycles with different precursor combinations. Each cycle deposits a specific layer composition, and by stacking multiple cycles with varying Ge:Sb:Te ratios, the patent achieves overall non-tie-line stoichiometries while maintaining the conformal deposition advantage of ALD in each individual cycle.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges multiple ALD deposition cycles with different stoichiometric compositions into a single multilayer structure. By combining layers with different Ge:Sb:Te ratios deposited through conventional ALD, the final composite material achieves non-tie-line stoichiometries that would be impossible in a single ALD cycle.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If PVD processes are used to deposit Ge2Sb2Te5, then various compositions can be achieved, but the process is not useful for depositing in small structures such as small vias or openings

Engineering Contradiction:

Improverange of achievable compositionsVSAvoidminimum feature size for deposition

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent makes ALD process universally applicable for both small structure deposition and achieving various compositions. By using ALD with multiple precursor combinations in sequence, the process gains the compositional versatility traditionally associated with PVD while retaining the conformal deposition capability in small features that ALD provides.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If conventional ALD processes with single precursor combinations are used, then simple process control is maintained, but only fixed stoichiometries on tie-lines can be produced

Engineering Contradiction:

Improvesimplicity of process controlVSAvoidstoichiometry flexibility

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic control into the ALD process by varying precursor combinations and cycle numbers across different deposition stages. The process transitions from static single-composition deposition to dynamic multi-composition stacking, allowing continuous adjustment of overall stoichiometry while maintaining simple ALD process control at each stage.

Inventive Principle:

Principle #15Dynamics

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 approach enables the formation of GeSbTe materials with tailored stoichiometries, such as Ge2Sb2Te5, GeSb4Te7, and GeSb6Te10, allowing for the adjustment of melting point, glass transition temperature, and crystallization speed, and facilitates deposition in small semiconductor structures where conventional methods fail.

Implementation Method 1

conventional ALD processes are well-suited for depositing highly conformal layers of GeSbTe materials in small openings or vias

Methodology Applied

Scientific EffectAtomic Layer Deposition: Chemical Vapour Deposition

Data Source

PatentUS9065048B2Methods of forming germanium-antimony-tellurium materials and chalcogenide materials

Publication Date: 2015.06.23 OVONYX MEMORY TECHNOLOGY LLC

AI summary

Methods of forming a material include exposing a substrate to a first germanium-containing compound and a second, different germanium-containing compound; exposing the substrate to a first antimony-containing compound and a second, different antimony-containing compound; and exposing the substrate to a first tellurium-containing compound and a second, different tellurium-containing compound. Methods of forming chalcogenide materials include exposing a substrate to a first precursor comprising a reactive precursor of a first metal and a co-reactive precursor of the first metal, the reactive precursor and the co-reactive precursor each having at least one ligand coordinated to an atom of the first metal, wherein the at least one ligand of the co-reactive precursor is different from the at least one ligand of the reactive precursor. The substrate is also exposed to a reactive antimony precursor and a co-reactive antimony precursor and to a reactive tellurium precursor and a co-reactive tellurium precursor.