Silicon nitride windows

This is Vivian Oehler's silicon nitride window cleaning technique:

I use 5M HNO$_{3}$ rather than the piranha etch. There is a recipe for the volume of acid needed to make up 300 ml in one of the red drawers. (It is basically 230 ml ddH2O and 70 ml concentrated Nitric Acid). All solutions are stirred during the procedure. The wafer has been broken apart and the windows are kept in Fluoroware crystal carriers.

1. Clean in 5M nitric acid for 1hr. (SPW heats to around 40C).
2. Rinse 2$\times$ in ddH2O
3. Clean in 70% ethanol for at least 1 hr. We have 95%, you need to dilute it. I usually do more but have done less if pressed for time.
4. Rinse 2-3$\times$ in ddH2O.
5. Soak in ddH2O for at least 1hr
6. Rinse 2$\times$ in ddH2O

I use the setup we developed for all steps except for the first fast rinse. (This setup just involves suspending the Fluoroware holder containing the windows from a wire. The wire is bent to fit around a handle which fits through the center of the Fluoroware holder.) I use a 1L beaker. With the wire setup 300 ml is a good volume for the solutions. The windows must be covered and the ethanol does evaporate, so you might want to cover the beaker during the ethanol steps.