Hexamethyldisilazane, min. 99% [HMDS]

Product Introduction

Hexamethyldisilazane (HMDS) is a widely used silylating reagent, surface-treatment reagent, and adhesion promoter in organic synthesis, analytical chemistry, semiconductor processing, and materials science.

Its highly reactive Si–N bond enables HMDS to transfer trimethylsilyl groups to suitable substrates. This makes it useful for derivatization of polar compounds and modification of hydroxyl-containing surfaces.

HMDS is also widely used to improve the adhesion of photoresists to silicon and silicon dioxide (SiO₂) surfaces. On hydroxylated surfaces, HMDS reacts with surface hydroxyl groups and replaces hydrophilic Si–OH sites with more hydrophobic trimethylsilyl groups.

Mechanism / Principle

Trimethylsilylation

HMDS can act as a source of trimethylsilyl groups. In the presence of suitable substrates and reaction conditions, it can convert active hydrogen-containing functional groups into their corresponding trimethylsilyl derivatives.

This process can:

• Reduce molecular polarity
• Reduce hydrogen bonding
• Increase volatility
• Improve GC compatibility
• Facilitate chromatographic analysis
• Modify surface properties

HMDS is recognized as a chromatographic derivatization reagent and is used for GC-MS sample preparation.

Surface Modification

For silicon-based surfaces, HMDS reacts with surface hydroxyl groups to generate trimethylsilyl-terminated surfaces. This reduces surface hydrophilicity and can improve photoresist wetting and adhesion.

This property makes HMDS particularly important in microelectronics and semiconductor processing.

Key Research Applications

1. Silylation and Derivatization

HMDS is used as a silylating reagent for converting suitable polar compounds into more volatile derivatives.

Applications include:

• Organic compound derivatization
• GC analysis
• GC-MS analysis
• Analytical method development
• Functional-group modification

HMDS has been described as a universal silylating reagent for alcohols, carboxylic acids, amines, amides, mercaptans, sugars, and related compounds.

2. Gas Chromatography

HMDS is used in analytical chemistry to improve the volatility and chromatographic behavior of suitable analytes.

Applications include:

• GC sample preparation
• GC-MS derivatization
• Metabolite analysis
• Sugar analysis
• Organic acid analysis
• Polar compound characterization

3. Semiconductor Manufacturing

HMDS is an important material in photolithography and semiconductor processing.

It is commonly used as a photoresist adhesion promoter on silicon and SiO₂ surfaces.

Applications include:

• Photoresist adhesion promotion
• Wafer surface treatment
• Silicon surface modification
• SiO₂ surface treatment
• Photolithography
• Microfabrication

Commercial HMDS products are specifically marketed for improving photoresist adhesion to silicon and SiO₂ surfaces.

4. Surface Treatment

HMDS can modify the surface chemistry of silica and other hydroxyl-containing inorganic materials.

Applications include:

• Silica surface modification
• Hydrophobic surface treatment
• Inorganic filler modification
• Surface energy control
• Materials research

5. Organic Synthesis

HMDS is used in organic synthesis as a reagent for introducing trimethylsilyl functionality and controlling the reactivity of functional groups.

Applications include:

• Protecting-group chemistry
• Silyl ether formation
• Functional-group protection
• Synthetic intermediate preparation
• Organosilicon synthesis

6. Silicone and Materials Chemistry

HMDS can also function as a surface modifier and water-scavenging reagent in selected materials applications.

Applications include:

• Silicone chemistry
• Sealant formulations
• Inorganic filler treatment
• Surface modification
• Polymer and materials research

Advantages

• Highly useful trimethylsilylating reagent
• Suitable for GC and GC-MS derivatization
• Effective surface-treatment reagent
• Improves photoresist adhesion
• Useful for silicon and SiO₂ surface modification
• Can increase surface hydrophobicity
• Applicable to organic synthesis
• Useful for silica and inorganic filler treatment
• Suitable for semiconductor research
• Available in high-purity research grades

Commercial products are available in grades including ≥99% reagent grade and 99.9% ReagentPlus®, depending on supplier and specification.

Storage & Handling

• Store in a tightly closed container.
• Protect from moisture and humidity.
• Store in a cool, dry and well-ventilated area.
• Minimize exposure to atmospheric moisture during use.
• Handle in a suitable fume hood.
• Avoid breathing vapors.
• Avoid contact with skin and eyes.
• Wear appropriate gloves, protective clothing, and eye protection.
• Keep away from heat, sparks, and open flames.
• Use dry equipment and containers where appropriate.
• Follow the product-specific SDS for detailed storage, handling, transportation, and disposal requirements.

HMDS is a flammable liquid and presents toxicity and irritation hazards. A current Sigma-Aldrich SDS classifies the substance under GHS as a Category 2 flammable liquid, with acute toxicity classifications for oral, inhalation, and dermal exposure.

Research Areas

Researchers and manufacturers working in the following fields may use Hexamethyldisilazane (CAS No. 999-97-3):

• Organic chemistry
• Analytical chemistry
• Gas chromatography
• GC-MS
• Semiconductor manufacturing
• Photolithography
• Microelectronics
• Surface chemistry
• Materials science
• Organosilicon chemistry
• Polymer chemistry
• Pharmaceutical analysis
• Natural-product analysis

Q1: What is Hexamethyldisilazane?

A: Hexamethyldisilazane (HMDS) is an organosilicon compound and silylating reagent with CAS No. 999-97-3, molecular formula C₆H₁₉NSi₂, and molecular weight 161.39 g/mol.

Q2: What is the abbreviation for Hexamethyldisilazane?

A: The most common abbreviation is HMDS. HMDZ is also used.

Q3: What is Hexamethyldisilazane used for?

A: HMDS is primarily used as a silylating and derivatization reagent, photoresist adhesion promoter, and surface-treatment reagent.

Q4: What is HMDS used for in semiconductor manufacturing?

A: HMDS is used to treat silicon and SiO₂ surfaces before photoresist coating. It modifies surface hydroxyl groups, increases surface hydrophobicity, and can improve photoresist adhesion.

Q5: Can HMDS be used for GC-MS?

A: Yes. HMDS can be used as a derivatization reagent for GC and GC-MS analysis of suitable polar compounds.

Q6: What is the molecular weight of HMDS?

A: The molecular weight is 161.39 g/mol. NIST reports 161.3928 g/mol.

Q7: What is the molecular formula of CAS 999-97-3?

A: The molecular formula is C₆H₁₉NSi₂.

Q8: Is Hexamethyldisilazane the same as Bis(trimethylsilyl)amine?

A: Yes. Hexamethyldisilazane, Bis(trimethylsilyl)amine, 1,1,1,3,3,3-Hexamethyldisilazane, and HMDS refer to CAS 999-97-3.

Q9: Is HMDS the same as TMCS?

A: No. HMDS is Hexamethyldisilazane (CAS 999-97-3), whereas TMCS is Trimethylsilyl chloride. They are different silylation reagents and may also be used together in certain derivatization systems.