Thanks for the quick response, Joe.

In fact, I just finished another test. Patternless a-Si deposition on
quartz seems to produce a good-looking film but some areas of the film,
especially around the edges of the wafer, peeled off when sonicated.
Having a good quality CVD SiO2 layer underneath helped a lot.  What you
said makes sense that my litho process may have affected the film
adhesion.  Although it is hard to understand why almost all of the film
was gone after 1165 (with or without underlying CVD oxide).  I guess
whether the film sticks also depends on the area in which it makes
contact with the substrate.  Poor adhesion probably shows up more
strongly for thin (10-50um wide, 0.5-2mm long) strips.

I'm trying another lift-off process with a greater overhang this weekend
and I'll keep you posted on the result.

Thanks again.

Trent

Joseph Grogan wrote:
> Hi Trent,
>
> That's odd, it sounds like you're doing everything right. I regularly
> ebeam evaporate a-si onto borosilicate glass with no problems and I
> would think quartz should be similar. I typically clean my glass in
> piranha (or recently nanostrip), rinse in DI water, and then dehydrate
> at 200C for a couple minutes before evaporating. My only suggestion is
> to try troubleshooting the problem by doing a run where you clean your
> substrate and just evaporate a-si without the litho step. At least
> that way you'll be able to say whether the litho step and the
> patterning of the resist are causing the problem.
>
> -Joe Grogan