Hello Temmuz,

We are doing similar kind of work for one of our users in our facility. And
we use black wax for protection of topside of the wafer apart from SIxNx.

Best
Amit

---------- Forwarded message ----------
> From: Temmuz 
> To: mems-talk@memsnet.org
> Date: Sun, 22 Aug 2010 02:14:29 +0300
> Subject: [mems-talk] KOH resistant paste
> Hello,
>
> I am trying to do back side etching to Si based SOI wafer entirely (500um
> etch).  As etchant, I am using %30 KOH at 80 degrees for 7-8 hours.  In
> order to protect the topside, I am using 500nm thick nitride layer, however,
> because of the void formations during PECVD SiN deposition process, KOH
> etches everything on the topside.  DRIE is not an option for me.  Finally I
> decided to paste my sample to glass in order to etch only the backside.
>  Does anyone know of a paste, like silver paste or epoxy, which can resist
> to extended hours of KOH etching without getting etched at all?
>
> OR!
>
> Do anyone know of a way which I can protect the topside of my sample during
> etching?
>
> P.S.  As I read the archives, I learned that Protek B3 coating or annealing
> to high temperatures (800 degrees) can work, however, as some of the members
> say, coating is hard to remove and I can not anneal up to 800 or more
> degrees since my features include Al (it has melting point of 660 degrees).
>
> Thank you.
>
> Temmuz CEYHAN


--
Dr. Amit Asthana
Senior Research Officer
Australian National Fabrication Facility(QLD Node)
Australian Institute of Bioengineering and Nanotechnology
The University of Queensland, Building 75, Room 260,
QLD 4072 Australia
Phone: +61 (0) 7 3346 3429(Office)
            +61 (0) 7 3217 0425 (Home)
            +61 (0) 432096210 (Cell)
Email: a.asthana@uq.edu.au
          amitasthana4@gmail.com
          amitasthana4@yahoo.com