Hi,

The following solution is great for cleaning a Gold surface,  use  3 parts
H2O2 and 1 part NH4OH. Be careful to let the solution cool before using the
solution. Also note that the Au will react with the solution and bubble.

Rick Morrison
Radant Mems Inc.


-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf
Of Juntao Xu
Sent: Wednesday, June 16, 2004 3:52 PM
To: [email protected]
Subject: [mems-talk] Au surface cleaning


Hello,

I am making chips with gold pads (10nm thick) for later AFM imaging. But I
encountered some problem. Following  is my process:

1. Pattern gold pads on 4" silicon wafer by lift-off
2. Coat 1um photoresist (no baking) for dicing surface protection
3. Dice wafer into chips
4. Clean chips by  Actone/methanol/Isp/DI water to remove dicing particles
and photoresist.
5. O2 plasma ahser descum

The problem is: when do AFM image of gold pad, there always have  a lot of
10-15nm particles on it while the outside silicon surface is pretty smooth
and clean. I also imaged the gold surface before dicing. It is clean and no
such particles. Is it because Au surface  is prone to absorb small particles
during the chip clean process, is there a way to clean them ?

Thanks!

Juntao

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