Dear Brubaker Chad

Could you please provide the more information about the cleaning for surface
activation prior to wafer bonding such as composition of RCA-1 and RCA-2,
temperature and time. As I have to do bonding between LPCVD deposited
oxide/nitride layers, will the surface activation method suggested by you is
applicable in my case.

If I use only Piranha solution for surface activation, can it leave the enough
OH groups on the surface for the initiation of Van der Waals force.

best regards
Prem


On Thu, 17 Apr 2008 Brubaker Chad wrote :
>Prem,
>
>In our experience, the best method we've seen for a wet chemical
>activation of surfaces prior to a direct bond is to use a reversed RCA
>cleaning process, with the HF/BOE portion of the protocol removed.
>
>So first clean the substrates using an RCA2 (HCl-H2O2-H2O) clean first,
>followed by an RCA1 clean (NH4OH-H2O2-H2O), followed by a final DI
>rinse. This will leave OH groups attached to the surface of the
>substrates, which will enhance the initial Van der Waals bond force (via
>hydrogen bonding).