Hello Everybody,

  I want to bond two Silicon wafers which are coated with a 2um layer of
CVD oxide. The oxide layer on one of the wafers is recessed and 1um of
metal (gold) is deposited (and patterned) inside the recessed region
(please check the illustration below). Since I have the metal layer on
the bottom wafer, I can not do an RCA clean on that wafer. This may
cause some photoresist to remain on the oxide layer, which as far as I
now, will cause bonding problems. Moreover, because of the metal layer,
I can not use high temperatures for bonding. An oxygen plasma cleaning
is possible, but I am not sure of its effect on bonding process and
quality.

  Does anybody have any experience with cases similar to this scenario?
I will highly appreciate any help and/or references for bonding this
kind of structures.

  Thank you in advance,
  Behraad


           _________________________________________________
          |                  Oxide                          |
           _________________________________________________
          |                                                 |
Top       |                  Silicon                        |
Wafer     |                                                 |
           _________________________________________________
          |                  Oxide                          |
           _________________________________________________

           ______________                        ___________
          |              \                      /           |
          |     Oxide     \                    /   Oxide    |
           ________________=======Metal========_____________
Bottom    |                                                 |
Wafer     |                  Silicon                        |
          |                                                 |
           _________________________________________________
          |                  Oxide                          |
           _________________________________________________