Advanced Materials for Electronics


Purified hexamethyldisilazane (HMDS) preparations promoting photoresist adhesion on silicon and other substrates.

HMDS – X10
10% HMDS solution in xylene

HMDS – X20
20% HMDS solution in xylene

HMDS – 100%
HMDS concentrate

HMDS – P20
20% HMDS solution in PGMEA


  • Ready-to-use preparations for surface treatment of silicon
  • Promotes photoresist adhesion on silicon and SiO2 films
  • Prevents lift-off at edges of photoresist and reduces undercutting
  • Ensures full-line resolution
  • Improves yields of MOS and integrated silicon devices

HMDS- Photoresist Adhesion with Hexamethyldisilazane


HMDS is a purified hexamethyldisilazane with the chemical formula [(CH3)2Si]2NH. The product is used to augment the adhesion of photoresist on silicon and SiO2 surfaces.

The effectiveness of HMDS on adhesion is correlated with the reactivity of this compound with surface hydroxyl groups to form a new siloxane end product, i.e. Si-O-Si(CH3)3. This newly formed termination on the substrate renders the surface more hydrophobic in character and leads to greater wettability by photoresist. The latter condition is a crucial factor in good bonding. As a result of these altered characteristics due to the surface chemistry, the treated silicon surfaces become highly compatible with both negative and positive photoresists.

HMDS is offered in usable concentrations diluted with xylene as HMDS-X10 and HMDS-X20. Special blends are supplied upon request.


Appearance Clear, colorless liquid
Density 0.77 g/cc
Index of Refraction 1.4
Molecular Weight 161.4
Boiling Point 126-127 °C
Flash Point 12.7 °C
Typical Purity 99+%
Sodium < 1 ppm
Iron < 1 ppm
Lead < 1 ppm
Copper < 1 ppm


HMDS preparations are generally applied to the silicon wafer while spinning, prior to the application of photoresist. As an alternative procedure, the wafers may be immersed in HMDS preparations and allowed to dry after removal.

Assay Parameter Unit Specification LM Grade
Assay (HMDS) % 99.92 min
Water (H2O) ppm 50 max
Color APHA Max 10
Chloride (Cl) ppm 2 max
Trailing Impurity % 0.024 max
UV abs at 270 nm 0.039-0.115
Aluminum (Al) ppb 0.8 max
Arsenic and Antimony (as As) ppb 0.4 max
Barium (Ba) ppb 0.03 max
Beryllium (Be) ppb 0.16 max
Bismuth (Bi) ppb 0.02 max
Boron (B) ppb 3 max
Cadmium (Cd) ppb 0.2 max
Calcium (Ca) ppb 2.2 max
Chromium (Cr) ppb 1 max
Cobalt (Co) ppb 0.1 max
Copper (Cu) ppb 0.5 max
Gallium (Ga) ppb 0.1 max
Germanium (Ge) ppb 0.12 max
Gold (Au) ppb 0.08 max
Iron (Fe) ppb 0.2 max
Lead (Pb) ppb 0.2 max
Lithium (Li) ppb 0.1 max
Magnesium (Mg) ppb 0.3 max
Manganese (Mn) ppb 0.2 max
Molybdenum (Mo) ppb 0.3 max
Nickel (Ni) ppb 0.4 max
Potassium (K) ppb 0.4 max
Silver (Ag) ppb 0.1 max
Sodium (Na) ppb 0.88 max
Strontium (Sr) ppb 0.1 max
Tantalum (Ta) ppb 0.12 max
Thallium (Tl) ppb 2 max
Tin (Sn) ppb 0.2 max
Titanium (Ti) ppb 2 max
Vanadium (V) ppb 0.4 max
Zinc (Zn) ppb 0.7 max
Zirconium (Zr) ppb 0.2 max
Particle Count, 0.5 um ppb 20 max