Your process seems ok.

I would bake a little bit lower Temps at 150°C for 5min. Higher
temperatures usually gives you a measurable roughness in AFM.
I don't use the stripper step and still obtain low Ohmic contacts. So,
give it a try.

In your ebeam evaporator it should be absolutely no problem. I deposit
in a Auto500 as well as Auto300 easily over 100nm.

Try to repeat the process and see what happens (sometimes, it just
goes wrong on the wrong day)

Best
Daniel

Zitat von landobasa :

> Hi Mike,
>
> I have checked that there was no cracking in PMMA film after UV
> stripping. I don't do post-develop baking either.
>
> The original intention of using UV Ozone stripper is to clean the
> remaining PMMA after developing. Perhaps I should try to skip this
> step in order to make sure whether the UV exposure cause the film
> cracking.
>
> Given your experience of depositing Ti with 1.5Å/s, then 0.6Å/s
> should not be a problem. My E-beam Evaporation is Edwards Auto 306.
> The distance from the source to the target is rather short (perhaps
> ~30-40 cm). 20nm of Ti deposition was accomplished with indicated
> temperature of 40 degree C. I am not sure whether such temperature
> is sufficient to crosslink PMMA.
>
> Btw, after spin-coating I baked the sample on hot-plate at 180
> degree C for 90s (following the manual from MicroChem). I understand
> that in some of nanofabrication facility websites, PMMA is usually
> baked at 170 degree C for 15 minutes.
>
> Could this be the reason?
>
> Thanks for your help,
>
> Lando