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Photo by Mohammad Bereyhi, EPFL - LPQM

Results (4)


Bulk and Sleeve Electron Beam Lithography for Silicon Nitride Photonic Crystals

This is a method to improve the quality of lithography - in particular electron beam lithography (EBL). During an EBL exposure the electrons undergo different scattering processes. One scattering process that plays an important role is the back scattering of the electrons from the substrate or different stacks of thin film present in the exposure stack. As a result the actual dose that the resist sees is quite different that the original exposure dose. This ...


High aspect ratio \mathrm{Si_3N_4} nanomembranes

A fabrication method for large-area, high-stress LPCVD \mathrm{Si_3N_4} membranes is presented. These devices can be used as mechanical resonators with very low dissipation, exploiting dissipation dilution. A phononic crystal pattern allows to work with a high-order localized mode, shielded from acoustic radiation in the substrate. The procedure is amenable to most research clean rooms, requiring conventional lithography techniques and wet etching in KOH for device undercut.


Effect of LPCVD \mathrm{Si_3N_4} deposition on \mathrm{Al_2O_3} etch-stop films

Alumina (\mathrm{Al_2O_3}) films are widely used in photonics and superconducting circuits as an etch stop or passivation layer. In silicon nitride (\mathrm{Si_3N_4}) fabrication, a widely used etching recipe is dry etching using a mixture of \mathrm{SF_6/CHF_3} gasses. In case of multi-stacked materials, one might be interested to etch the \mathrm{Si_3N_4} layer with an stop layer to protect the rest of the stack from the etching step. \mathrm{Al_2O_3} is a great etch stop layer for \mathrm{Si_3N_4} ...


UV light from ambient environment increases the \mathrm{Si_3N_4} etch rate in \mathrm{XeF_2} etching

Releasing mechanical structures is a fundamental step in MEMS processing. Given the wide usage of silicon nitride ( \mathrm{Si_3N_4} ) on silicon (Si) carrier due to high stress and high mechanical Q factors, high etching selectivity between \mathrm{Si_3N_4} and Si is very crucial for the release process. Here we demonstrate that UV light from ambient light sources in a cleanroom environment (EPFL - CMi) can increase the etch rate of \mathrm{Si_3N_4} ...