To pattern SiO2 you should use BOE (buffered oxide etch) or a plasma etch.
In my experience, photoresist doesn't hold up very well to HF, without the
addition of ammonium fluoride.

Roger Shile

----- Original Message -----
From: "Andreas Jahn" 
To: 
Sent: Tuesday, March 04, 2003 1:36 PM
Subject: [mems-talk] Adhesion problems after etching with TMAH


> To all,
>
> does anyone know, what could cause adhesion problems of photoresist on
SiO2
> after etching in TMAH?
> I oxidize a Si-wafer (double polished) and pattern the SiO2 on the
backside.
> Then I etch it in TMAH. If I want to pattern the
> same SiO2 on the frontside, the HF undercuts the photoresist even with the
> use of HMDS as an adhesion promoter.
> It is the same procedure than the backside. Thanks for your help.
> -Andreas
>
>
> _______________________________________________
> [email protected] mailing list: to unsubscribe or change your list
> options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk
> Hosted by the MEMS Exchange, providers of MEMS processing services.
> Visit us at http://www.memsnet.org/