> The metal I'm interested in is Al on
> Si. I would actually prefer an Au surface, but I would need a diffusion
> barrier for Si and Ti, a diffusion barrier for Ti-Pt and then hope that Au
> does not evaporate off at those temperatures. So with that respect, I'm just
> currently sticking to Al on Si for simplicity. Some of the literature out
> there suggests using TiN or TiW. But most of these systems do not
> characterize the films at more than 600C. I would like to find out if anyone
> has ever done Al on Si wafers at such elevated temperatures for extended
> periods of time and what was done to negate the diffusion of Si into Al. I
> am unsure of what type of Si bonder my facility will be obtaining, but I
> know at least it has to survive 800C.

Okay, pure Al has a melting point of 660C, so there are good reasons why
there is not much "film" data at 800C. Even if you avoid diffusion into Si
(TaSiN might be a barrier candidate), the remaining metal will dewet and
agglomerate or just drip off the wafer.

Gold melts at 1330C, so evaporation would not be an issue, but you'd need a
damned good diffusion barrier. Thick, bias-deposited TiWN comes to mind.
Why would you involve Ti and TiPt?

Temperatures of the resistive heating elements in inkjet printheads reach
600-800C, duty times are short, but the number of duty cycles is very high.
TaAl is used as the heater, Ta as an ink barrier.

> The Al wafer I require on the surface will probably need to be pure for an
> optical reflectivity point of view and thus am unable to use the Si-Al type
> depositions. The Si wafer I use is pure undoped Si (>10k Ohms).

Sorry, I do not understand this. Reflectivity of most Al alloys is very,
very close to pure Al. Gold and refractory metals would only be 50%, thick
TiN <10%. If reflectivity is a killer criterion, the only metal coming
close to Al is silver.

Cu on TaSiN has been shown to withstand 900C for 30min but again,
reflectivity would be much lower than Al or Ag.

klaus

--
Klaus Beschorner
Metron Technology, European Applications Manager