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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