Hi,
The problem of not getting flat surface/uniform coating of SU8 2005 may be
because of your spin coating parameters. Try coating your wafer with 500 rpm for
10 seconds & then 3000rpm for 30 seconds. The only problem I had faced  with Su8
2005 was that the edges of my wafer didnt get coated entirely. But in my case it
doenst matter as I dont use the edges. Also see to it that you have placed the
centre of your wafer correctly on the chuck of the spin coater which is another
reason to not get a uniform coating.





________________________________
From: dai truong 
To: General MEMS discussion 
Sent: Fri, June 10, 2011 9:27:28 PM
Subject: Re: [mems-talk] make the su-8 surface flat

Hi Eric,

If I use Su-8 2005 (film thickness 3.8um) in a sample with 1.5 um height
difference, Can I get the flat surface if I use your method?

Thank you!