HSQ resist for replication stamp in polymers

We investigated an affordable, accurate and large scale production method to fabricate sub-wavelength grating structures by replication in polycarbonate substrates by hot embossing. We used hydrogen silsesquioxane (HSQ) a high resolution, binary, inorganic, negative electron beam resist, on silicon substrate to make a stamp for replication. We fabricated the stamp on silicon by using HSQ-resist without any etching process with simple process steps. The process starts by depositing an HSQ-resist layer on a silicon substrate and by a measurement of the desired film thickness by adjusting the spinning speed and time. The resist material is then subjected to e-beam writing followed by a heat treatment to enhance the hardness and to reveal properties analogous to solid SiO2 as a hot embossing stamp material. A comparison study is made with and without the etching process with different etching rates. We demonstrate that an effective and inexpensive stamp for thermal nano-imprint lithography (NIL) for optical gratings is provided without an etching process, which gives a uniform imprinting density over the entire grating surface and high imprint fidelity. The reflectance spectra of replicated grating structures are also shown to be in agreement with theoretical calculations.