Photo by Matthias Neuenschwander, EPFL - LBNI

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Critical point drying of suspended structures after wet etch

In this report I monitor a full successful cycle of critical point drying (CPD) run for drying MEMS sensors after wet release using KOH etching. The pressure and temperature of the CPD tool (Tousimis) is monitored during the process and plotted in a P-T diagram with \mathrm{CO_2} critical point. A few notes for higher yield in the drying process are mentioned in this report as well.

Dependence of stress in thin Al films on deposition and post-deposition temperature conditions

Here we present our study of the stress dependence in Al thin films on deposition conditions. We consider two types of Al 100-nm thick films: E-beam evaporated films and films obtained by magnetron sputtering. We investigate the Al film stress hysteresis in the environment with slowly increasing and decreasing temperature, i.e. during the gradual annealing. We consider the effect of deposition temperature on the film stress and grain size. We conclude that the annealing of ...

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.