Neal:

Thanks for taking the time to respond to my question. Do you have any experience
with Nano powders of smaller size say 30 nm. Since the trench opening is only 1
micron but 20 micron deep I think I might need something of a smaller size than
the glass frit powder you mentioned. Again thanks Bob Henderson

-----Original Message-----
From: neal@zbzoom.net
Subject: Re: [mems-talk] Dielectric fill material for deep trenches

Dear Bob,

Hello, you may be able to fill this with a glass frit powder applied with a
doctor blade? or you can use a spin on polymer that may fill this trench. Some
of these frits are used for glass passivation of medium power solid state
devices and the moats they fill are quite large. The powders are ground to a
size near 25 microns and they soften and melt at or below the temperatures you
mention.

Of course the polymer is not an SOG but can permanently or temporarily fill the
trench and then could be heated and removed leaving an air gap or bridge if this
is of interest?

There are some types of SOG that can do 1 micron but filling this trench I think
would be difficult. There is one type of SOG that does flow at a temp of 180 deg
c perhaps this might be of interest I would think a slow spin for dispersion and
gap fill may have some potential but this is something that would require some
empirical work.

I have mixed the Frit with the SOG and can get a fairly uniform distribution of
glass particles when spun. The glass frit can also be silk screened on or
applied using electrophoresis.