Hi

I doubt companies have any special tricks which aren't already out there
in the literature but they probably have more rigorous process
development and better facilities to obtain better reliability. In
particular they probably invest in commercial bonding systems rather
than use a furnace which may suffer from poor uniformity.
Flatness of your wafers and thorough pre-treatment are very important.
You can also use a grid channel network around your structures to
improve air circulation and minimise the risk of voids. Minimise the
area you use (i.e. don't expect to be able to bond a full size wafer and
then dice multiple structures afterwards).
There are some low temperature glass bonding techniques which may be
worth a look. One involves dilute HF to activate the surface.
Part of the trick may be getting a good "pre-bond". If you have flat
clean wafers, they will stick together tightly forming a vacuum bond.
Then put them in the bonding oven.
As Isaac says, there is no one "magic pill" but if you have adequate
tools and are prepared to spend time on rigorous development then you
should be able to achieve a reproducible protocol.
Best regards

Gareth

Mikael Evander wrote:
> Hello.
>
> I'm familiar with the "standard" glass-glass thermal fusion bonding method
where you wash your glass wafers, preferable surface activate them with
O2-plasma or such-like and thermo-cycle them in an oven a bit over Tg with some
pressure on the wafers. As far as I know most people using this get a pretty low
bonding efficiency, some voids and usually not the nice "mirror-finish" on the
glass that you usually see before you bond.
>
> I'm also aware that the companies doing glass-structuring and bonding
commercially must have, and have, much better bonding efficiencies and
incredably good looking bonding.
>
> I find it kind of surprising that whatever tips and tricks are being used in
getting at least a slightly better bond hasn't seeped out from the industry. As
far as I know at least ...
>
> Does anyone have any nice tips and tricks to share that would help me, and
hopefully lot of other people, to get more efficient bonding?
>
>