Hexamethyldisilazane (HMDS)

For quartz, glass, or silicon wafers with a natural oxide layer, the SiO2 on the surface will form polar -OH bonds on the surface when it is exposed to atmospheric humidity for a long period of time, and the substrate will show hydrophilicity. This hydrophilic surface will show very poor affinity for non-polar or low-polar photoresists, resulting in photoresist detachment. Therefore, tackifiers are needed to improve the hydrophobic properties of the substrate surface.

Hexamethyldisilazane (HMDS) is a commonly used tackifier with the molecular formula (CH3)6Si2NH. The principle of its role is Si(CH3)3 in the Si end of the bond with the substrate, the hydrophilic -OH bond into Si-O bond, and non-polar -CH3 is away from the substrate to form a hydrophobic surface, and photoresist in the molecular group composed of C, H, O to form a stronger force, so as to realize the substrate and photoresist good adhesion.


CAS NO.999-97-3
Molecular weight161.39
AppearanceColorless clear liquid
Purity≥ 99.8%
Flash point27 ℃
Refractive index (25 ℃)1.406-1.410
Density (25 ℃, g/cm3)0.770-0.780
Moisture≤ 100 mg/kg
Non-volatile content≤ 1.5 mg/kg

Method of Use

1. Evaporation Coating Method

Directly diffuse HMDS in a closed container and then operate. Process at room temperature (20~25 ℃) for 5-10 min, or at high temperature (70-80 ℃) for 5-10min. Since it is a flammable liquid, pay attention to safety when using it at high temperature.

2. Nitrogen Bubbling Method

This method of using HMDS is easy to apply in an integrated production line, where the processing equipment is placed before the photoresist is coated. Process at high temperature (50~70°C) for 40-60s.

3. Rotary Coating Method

HMDS is coated on the wafer using a homogenizing device at 3000~5000rpm/s. Process at 70°C for 1-5min.

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