Hi there,

I used Pad Etch solution, if you can't buy it, try this recipe
35 ml of Acetic acid
12 mg of Ammonium fluoride
15 ml of Ethylene glycol
35 ml of DI water

Etch rate SiO2: metal  is about 10:1 but practically it etches SiO2
faster and better for metal.

Good luck.
Araya  Pothisorn
UniSA, Adelaide
South Australia


-----Original Message-----
From: QAZI, MUHAMMAD [mailto:qazi@email.sc.edu]
Sent: Tuesday, 25 May 2010 2:44 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Does BOE solution disolve Ti/Al/Ti/Au?

Dear all,

Sample: AlGaN/GaN (2um) on Silicon substrate (500um)
Size: 1.4cmx1.4cm pieces

At some point of my process line I have Ti/Al/Ti/Au contact on the top
side. After that, I had to deposit PECVD 12um oxide on the back side to
have pockets for Si etch (SiO2 acts as masking layer for anisotrpic Si
etch- Bosch process). After I dip it in BOE soltion, the top contacts
wash away :( .

Any solution or suggestion?

Muhammad Qazi
Dept of EE
University of South Carolina