Whenever I have to mount a smaller wafer/die to a wafer I always just
use photoresist (Shipley 1827 in my case).  Just a small drop in the
center and press the wafers together (if you are going into vacuum
you want to do them rough side together to reduce the number of
bubbles).  Soft bake at 100deg C for 5 min to make sure it hardens.

When you are done just put on a hotplate at 200degC for 1-5 min and
the wafers should easily separate (either the PR becomes brittle and
cracks or it reflows and becomes liquid again, I have seen both
happen).  Acetone, Pirahna etch, or oxygen plasma to clean the
backside later if you need.

Nicolas Duarte

At 2:42 AM +0800 8/17/06, Cheng-Yu Hsieh wrote:
>Hi Everybody,
>I am trying to bond one 4 inch silicon wafer to a 8 inch silicon wafer.
>I need a temporary bonding adhesive which I should be able to remove
>after I have done chemical mechanical planarization process on the 4
>inch wafer.
>
>Does anybody know of commercially available adhesives
>that I can use for this? I need an adhesive which is
>very  simple in it's application and ideally would
>like something which I can just apply in-between the
>two wafers and then stick them together and later
>should be able to de-bond them easily too.
>