Actually, as to me, I suffered a problem that I have Au+Cr (adhesion layer)
on top of SOI wafer. Then device layer was DRIE through and stopped at
Buried oxide. But the metal (Au in my case) on top of Cr started peeling
after BOE and critical point dry.

So it seemed to me that the BOE or HF vapor did weaken the adhesion provided
by Cr, especially when the metal layer experienced a stress.

btw, I still don't understand your process flow...

On Wed, Feb 25, 2009 at 12:28 AM, Taekyung Kim  wrote:

> Hi folks,
>
> I have a problem with Cr etching after HF vapor or BOE treatment.
>
> 30 nm of Cr blanket layer is deposited on 100 nm thermal oxide. Then, 40 nm
> thick Pt electrodes are defined by electron beam lithography.
> After another EBL, a window is defined around one of the electrodes. In the
> open window (6um x 10um), 300 nm width Pt electrode on top of Cr
> (30nm)/SiO2
> (100nm) is exposed.
> Cr etchant (~200 nm/min) removes Cr layer and SiO2/Si layer is etched in
> CF4/SF6 RIE. Now Pt/Cr/SiO2 beam is suspended. I was able to remove SiO2
> layer with HF vapor or BOE. But the problem is that Cr layer is exposed to
> HF vapor or BOE, it is not easily etched in Cr etchant. It took several
> minute and all the Pt electrodes were peeled off. Can Cr layer be changed
> during CF4/SF6 RIE process or during HF treatment?
>
>
> Thanks
>
> TK

*  Zou Jie (Jay)
*  Department of Physics
*  University of Florida
*  Tel: +1-352-846-8018
*  Email: zoujiepku@gmail.com
*  Homepage: http://plaza.ufl.edu/zoujie/