Hexamethyldisilazane

Hexamethyldisilazane (CAS 999-97-3), commonly abbreviated as HMDS, is a silylating agent used in semiconductor fabrication, surface chemistry, and specialty coatings. Also known as bis(trimethylsilyl)amine.

Where is Hexamethyldisilazane used?

• Semiconductor manufacturing: photoresist adhesion promoter for silicon wafer surfaces
• Surface treatment before lithography to prevent delamination and improve pattern resolution
• Pharmaceutical and analytical laboratories: silylation of active compounds
• Chromatography column packings: improved compound stability and peak symmetry in GC analysis
• Specialty coatings: surface modification of silica and titanium dioxide for dispersion in hydrophobic resin systems
• Personal care: HMDS-treated powders in cosmetic products for improved skin feel and moisture resistance
• It converts surface hydroxyl groups into trimethylsilyl groups, rendering substrates hydrophobic.

Good to know: Technical and reagent grades are the most commonly available; semiconductor-grade material is available under tighter purity controls for microelectronics.

Commercial specifications

• Purity specifications typically at 97% or higher depending on application requirements
• Standard packaging from small reagent quantities up to bulk drums