1. What is a Hybrid Polymer (ORMOCER®)?
Hybrid polymers exhibit both inorganic and organic units and thus combine superior properties in one material class, e.g. outstanding optical transparency and non-yellowing behavior, high thermal and chemical stability as well as excellent mechanical stability.
Hybrid polymers are derived from the ORMOCER®s (Organically Modified Ceramics), which were initially developed by the Fraunhofer Institute of Silicate Research (FhG ISC), Germany. ORMOCER® is a trademark of the Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. München.
2. Are there any processing guidelines for the Hybrid Polymer products available?
For each Hybrid Polymer processing guidelines are available, which come with the delivery of the product. Please contact the corresponding product manager if you need further processing details in advance or use our contact form.
3. What are the Tg (glass transition temperature) values for the Hybrid Polymers?
Hybrid Polymers form a three-dimensional polymer network during curing, so no glass transition occurs once the material is crosslinked. Hybrid Polymers are duromeric.
4. Can I get Hybrid Polymers with lower film thicknesses?
Apart from the standard Hybrid Polymer products (see product listings) micro resist technology GmbH provides diluted Hybrid Polymer solutions customized for lower film thicknesses as special designs on request. The minimum attainable film thickness for the Hybrid Polymers is around 100 nm.
5. Does micro resist technology provide thinners for the Hybrid Polymer products?
In case you want to dilute a Hybrid Polymer by yourself in order to obtain thinner films after spin-coating, we provide the following solvent systems.
- OrmoThin – Dilution for d > 0.5 μm (product-specific) *
- ma-T 1050 - Dilution for d < 0.5 μm (product-specific) *
* More detailed information about the dilution of Hybrid Polymers can be found in the processing guidelines.
6. Is it possible to increase the adhesion of the Hybrid Polymers on substrates like glass, fused silica, or Si?
For glass, SiO2, or metal surfaces it is advisable to use an adhesion promoter such as OrmoPrime®08. For processing information please see the OrmoPrime®08 processing guidelines.
7. Do I have to apply a release agent on mould, template or mask?
We strongly recommend to apply a release agent on the mould or stamp in order to generate a high adhesion contrast between mould or stamp and substrate. It is advisable to pre-treat the lithography mask, even if only a proximity lithography process is performed. The formed anti-sticking layer (ASL) prevents defects caused by sticking of the Hybrid Polymers on the mould/stamp. The most common release agent for silicon or silicon dioxide is “F13-TCS” (1H,1H,2H,2H-perfluorooctyl-trichlorosilane, CAS number [78560-45-9], available from common specialty chemicals suppliers).
The processing of F13-TCS for Si and SiO2 moulds is described in: S. Park, “Anti-adhesive layers on nickel stamps for nanoimprint lithography“, Microel. Eng. 73-74 (2004), 196-201; H. Schift et al., „Controlled co-evaporation of silanes for nanoimprint stamps“, Nanotechnology 16 (2005), 171-175.
8. Can Hybrid Polymers also be cured thermally? Why are heating steps recommended?
Hybrid Polymers are only curable by UV exposure. The recommended heating steps fulfill other purposes:
- The prebake step is recommended in order to remove possible air inclusions and to improve the uniformity of the hybrid polymer layer after the coating process. The prebake is mandatory when the Hybrid polymer is diluted by a solvent. Please note: Hybrid polymers do not harden during the prebake step and are still viscous thereafter!
- The recommended post-exposure bake as well as the subsequent hardbake-step is recommended in order to increase the thermal and environmental stability and for improving the adhesion to the substrate.
9. Removal of cured Hybrid Polymers?
As Hybrid Polymers form a three-dimensional polymer network during curing, drastic conditions for removal are necessary. The solvent PGMEA, NMP-based solvents, or NMP-free alternatives in an ultrasonic bath at higher temperature (40–60 °C) for several hours will usually result in a peel off. Hot piranha etch is also suitable. Alternatively O2/ CHF3 plasma can be used to remove the cured hybrid polymer. Do not use pure oxygen plasma! Porous SiO2 will be formed.
10. What is the so-called „inhibition layer“? Which Hybrid Polymers form such an inhibition layer?
OrmoClear®, OrmoCore and OrmoClad as well as many acrylic-based polymers form a so-called inhibition layer when exposed under ambient atmosphere. This is due to partial quenching of radical polymerization by oxygen which results in a 5–15 μm thick layer of uncured material on the surface (“inhibition layer”). It has to be washed away in a development step (e.g. with OrmoDev). However, OrmoComp® and OrmoStamp® are not sensitive to oxygen and do not form an inhibition layer.
When applying UV moulding or (nano)imprint with hard molds (e.g. Si-, SiO2-, Ni-molds) there is no formation of an inhibition layer. However, using PDMS-molds (acting as some kind of “oxygen sponge”) will result in the formation of an inhibition layer.