Kris,
I had a similar experience with etching Si in Xactix...
which tool from Xactix do you have....
If you can increase the temperature of the bottom chuck....with your tool..I
would recommed that you try to do your etch at about 55deg..
If you cannot set the temperature...try pre-heating your wafer before
etching....




On 5/24/07, kris  wrote:
>
> Hello,
>
> In continuation to my previous posting (XeF2 attack on
> Tungsten), I have another question.
>
> Does XeF2 etch on Si leaves any residue??
>
> I am trying to etch Si wafer which is bonded to
> another wafer. Both the wafers has Au patterned on
> them and are Au-Au thermocompression bonded. The top
> wafer (which is etched in XeF2) has the Tungsten
> adhesion layer between the gold and silicon wafer.
>
> After the complete removal of the top silicon wafer
> (STS DRIE and XeF2 etches), I can clearly see that the
> Tunsten is etched away completely which confirms the
> answers from the previous posting.
>
> Also, I can find some residue left on the bottom
> wafer. I have performed the EDAX on the material that
> was scattered on the entire Au and SiO2 layers on the
> bottom wafer. The content of Si is more than any other
> material.
>
> I was wondering if the Si etched in the XACTIX got
> redeposited as a thin layer on the bottom wafer?? Or
> is it the thin native or virgin oxide of the bare
> silicon top wafer that was etched??