Dear Pietro,

If I were you, I would try to bond the 2 SU8 wafers in a regular oven with a
simple weight of them and forget about Al-Al coating and bonding. If you need
alignment, check with your fab staff if you can put the alignment jig in an oven
@ 150°C or so.

Matthieu


> Message: 1
> Date: Fri, 3 Feb 2012 14:44:33 +0100
> From: "Pietro Maoddi" 
> Subject: [mems-talk] Low temperature Al-Al bonding
> To: 
> Message-ID: <255A4F51F49F4730913B6A789E6B5BC8@Lappie>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>       reply-type=response
>
> Hello everyone,
>
> I need to bond hermetically two wafers on which there are SU-8 structures
> coated by a 500nm Al film (deposited by sputtering); the interface to be
> bonded is therefore Al-Al. Since I need a very low temperature process (200
> ?C max) to avoid destroying the SU-8 structures themselves, I originally
> planned to perform an adhesive bonding with an SU-8 interlayer, but it turns
> out I cannot do this with our Suss SB6 bonder because of contamination
> problems (uncrosslinked SU-8 is not allowed in the bonder).
>
> Does someone know any other technique to hermetically bond an Al-Al
> interface at low temperature? I suspect it should be possible to perform
> some intermetallic bonding by depositing another metal layer but I cannot
> find any suitable publication describing the technique for aluminum.
>
> Thanks in advance,
>
> Pietro