Hafnium Amide Purification via Sulfonyl Complexation

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Solution Overview

Problem

Current methods for producing high-purity hafnium amide are inefficient in removing zirconium impurities, which are challenging due to their similar chemical properties and vapor pressures, leading to high concentrations in hafnium amide used in semiconductor gate insulating films.

Innovation Solution

A process involving the addition of compounds containing carbonyl or sulfonyl groups to crude hafnium amide, followed by distillation under reduced pressure, effectively separates and reduces zirconium components, achieving high-purity hafnium amide with a concentration of 100 wtppm or less.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If simple distillation under reduced pressure is used, then the process is simple and fast, but zirconium and hafnium cannot be separated due to similar vapor pressures

Engineering Contradiction:
Improvesimplicity of separation processVSAvoidpurity of hafnium amide
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

A silane compound is introduced as an intermediary reagent that selectively reacts with zirconium amide to form a zirconium-silane complex. This mediator creates a chemical difference between zirconium and hafnium compounds, enabling separation through distillation despite their initially similar vapor pressures.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The chemical properties of zirconium amide are changed by reacting it with silane compound, transforming it into a zirconium-silane complex with different vapor pressure characteristics. This parameter change in chemical composition enables subsequent separation by distillation.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If liquid-liquid extraction with hexone is used, then zirconium and hafnium can be separated, but running costs increase due to poor solvent recovery

Engineering Contradiction:
Improvepurity of hafnium amideVSAvoidrunning costs of separation
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The separation process utilizes phase transition through distillation instead of liquid-liquid extraction. By controlling vaporization and condensation, the method achieves separation based on vapor pressure differences after silane treatment, avoiding the need for solvent recovery infrastructure and reducing operational costs.

Inventive Principle:
Principle #36Phase transitions

3Manufacturing precision

If fractional distillation is used for tetrakis(dimethylamido)hafnium, then zirconium component can be removed, but the process cannot be applied to other hafnium amides

Engineering Contradiction:
Improvepurity of hafnium amideVSAvoidapplicability to different hafnium amides
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The silane treatment method serves as a universal preprocessing step that can be applied to various types of hafnium amides (tetrakis(dimethylamido)hafnium, tetrakis(ethylmethylamido)hafnium, tetrakis(diethylamido)hafnium). The silane compound universally reacts with zirconium components across different hafnium amide types, making the separation approach broadly applicable.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 process significantly reduces zirconium concentrations from 1,000-5,000 wtppm to 10 wtppm or less, ensuring high-purity hafnium amide suitable for semiconductor film formation, maintaining high yield and stability.

Implementation Method 1

adding a compound which contains a carbonyl group or sulfonyl group and is represented by the formula of A(OyXOnRf)m

Methodology Applied
Scientific EffectComplex formation: Chemical Bonding

Implementation Method 2

subjecting a product of the step (a) to a distillation under reduced pressure, thereby removing the zirconium component from the crude hafnium amide

Methodology Applied
Scientific EffectDistillation: Distillation

Implementation Method 3

Since tetrakis(diethylamido)hafnium and tetrakis(diethylamido)zirconium have almost no difference in vapor pressure and have similar chemical properties, their separation is difficult by a simple procedure, such as simple distillation under reduced pressure

Methodology Applied
Scientific EffectVapor pressure difference: Vapour Pressure

Data Source

PatentUS7319158B2Process for producing high-purity hafnium amide
Publication Date: 2008.01.15 CENT GLASS CO LTD

AI summary

A process for producing a high-purity hafnium amide includes the steps of (a) adding a compound which contains a carbonyl group or sulfonyl group and is represented by the formula of A(OyXOnRf)m (e.g., CF3SO3H, Hf(CF3SO3)4, (CF3SO2)2O, CF3CO2H, CH3SO3H, C6H5SO3H, and (CH3SO2)2O), to a crude hafnium amide which is represented by the formula of Hf[N(R1)(R2)]4, where each of R1 and R2 independently represents a methyl group or ethyl group, and which contains a zirconium component as an impurity; and (b) subjecting a product of the step (a) to a distillation under reduced pressure, thereby removing the zirconium component from the crude hafnium amide.