Hi all,

I have a question for anyone who makes silicon nitride
windows/membranes. I plan on making nitride windows for TEM applications.

I will be purchasing LPCVD nitride coated silicon wafers which I'll
pattern myself to produce freestanding windows. I need to decide between
low-stress nitride and stoichiometic nitride and I've heard differing
opinions on which makes better windows. The argument I've heard for
low-stress nitride is that the film is less likely to break because it
isn't as stressed. But the argument I've heard for stoichiometic nitride
is that it's more selective in KOH so I'm less likely to over-etch and
since its pre-stress is tensile, this actually helps make the membrane
flatter.

My film thickness will be 50nm. If anyone can share some advice I'd
appreciate it.

thanks,
Joe