https://nanyte.com/photoresists/hmds · last updated 2026-07-26
- Manufacturer
- MicroChemicals GmbH (application-note publisher; HMDS itself is a commodity chemical sold by many suppliers, not a single manufacturer's proprietary product)
- Tone
- Not photoimageable (underlayer)
- Chemistry
- Ancillary (not photoimageable)
- Exposure dose
- Not exposed — dissolves in developer
- Substrate
- Primer
- Resist
Spin coating
The manufacturer does not publish a spin curve for HMDS (Hexamethyldisilazane).
- HMDS must not be spin-coated as a liquid — the only correct application is vapor-phase, via a nitrogen-carrier 'bubbler' held at room temperature feeding a heated (75-120°C) substrate, where HMDS bonds chemically as a monolayer ("Correct Use of HMDS", Fig. 47-48, p.2).
- If liquid HMDS is spun on instead, the resulting layer is only physically (not chemically) bound; ammonia released from it during the resist softbake diffuses into and cross-links the resist near the substrate, suppressing development and degrading resolution and profile ("Incorrect Application of HMDS", Fig. 49, p.2-3) — this failure mode is explicitly documented, not inferred.
- For the same reason, the note advises against applying HMDS in the same spin coater used for resist coating (slow HMDS evaporation can contaminate later coating runs); if spin-application is unavoidable, it recommends a 100-120°C water-desorption bake beforehand, a 100-120°C thermal-activation bake afterward, and strict spatial separation from resist-coating equipment (p.3).
- There is no legitimate spin-speed-vs-thickness relationship for a vapor-deposited chemisorbed monolayer, so HMDS has no spin curve at all — that is the chemistry, not missing data.
- Adhesion
- HMDS not required — Not applicable — this entry describes HMDS itself (the adhesion promoter), not a photoresist that would require HMDS pretreatment.
Prime
- Prime
- 75–120 °C
- Notes
- Vapor-phase application: HMDS vapor is carried by dry nitrogen from a room-temperature bubbler onto a substrate held at 75-120°C, where it bonds chemically as a monolayer.
SOURCE: Correct Use of HMDS / Incorrect Application of HMDS, p.2-3; Adsorbed Water, p.1
Exposure
HMDS (Hexamethyldisilazane) is not photoimageable. It is not exposed at all — it is coated beneath an imaged top resist and undercut laterally during development. See the development step below.
Development
Not published for this resist: Developer, Dilution, Time, Method, Rinse — characterize on-tool.
Hard bake, etch & strip
Not published for this resist: Hard bake, Descum, Etch resistance, Stripper, Storage — characterize on-tool.
Where it's used
Practical notes from the datasheet
HMDS (hexamethyldisilazane) is a vapor-phase adhesion promoter, not a photoimageable resist: it converts a hydrophilic, OH-terminated oxide surface (native or thermal SiO2, quartz, glass, most base metals) into a hydrophobic, resist-wetting surface by chemically bonding a monolayer of non-polar trimethylsilyl groups, releasing ammonia as a byproduct (p.2). The only correct application is vapor-phase, via a nitrogen-carrier bubbler at room temperature feeding a substrate heated to 75-120°C; spin-coating liquid HMDS instead yields only a physically bound layer whose ammonia, released during the subsequent resist softbake, diffuses into and cross-links the resist near the substrate, suppressing development and degrading resolution — a failure mode this note documents explicitly as 'Incorrect Application' (p.2-3). On noble metals without native oxide (gold, platinum), HMDS and other organic adhesion promoters show little to no adhesion benefit because they cannot chemically bond to the surface; base metals such as Al, Cr and especially Ti already adhere well without a promoter (p.3-4). This document is a general MicroChemicals application-note chapter ('01 Chapter — Basics of Microstructuring: Substrate Preparation'), not a manufacturer technical datasheet for a specific HMDS product or grade — HMDS itself is a commodity chemical sold by many suppliers, and this note is the correct place to attribute process guidance about it rather than any single vendor's TDS.
Sources & disclaimer
- MicroChemicals GmbH (application-note publisher; HMDS itself is a commodity chemical sold by many suppliers, not a single manufacturer's proprietary product) — HMDS (Hexamethyldisilazane) datasheet · accessed 2026-07-10
- Kawai and Kawakami. Characterization of SiO2 Surface Treated by HMDS Vapor and O2 Plasma with AFM Tip. Journal of Photopolymer Science and Technology (2003). doi:10.2494/photopolymer.16.665Silicon oxide substrates are silane-coupling treated with HMDS and separately exposed to oxygen plasma, then probed with an AFM tip to characterize the resulting surface. Measures the surface change that HMDS priming is performed to produce, on the oxide that resist is subsequently coated onto.
Manufacturer datasheet values are starting points; optimal parameters depend on your substrate, equipment and environment. Product names and trademarks belong to their respective owners. NANYTE is not affiliated with the manufacturers listed. Last updated 2026-07-26.