Hi, try my recipe for ~22um thick

step 1: 70rpm, 30r/s, 20s
step 2: 400rpm, 100r/s, 20s
step 3: 1000rpm, 200r/s, 60s

baking: 80 degree for 1 min, then 110 degree for 3~4 mins.

I could easily get over 20um thick resist through one spin-coating. I did not
try any double layer, but I think it is worth to start with one layer. In the
case of double layer, the baking time needs to be adjusted. Also, I normally
left the wafer overnight for rehydration.

Hope this helps.

Yingtao

________________________________________
From: mems-talk-bounces+y.tian2=lboro.ac.uk@memsnet.org [mems-talk-
bounces+y.tian2=lboro.ac.uk@memsnet.org] On Behalf Of Shahzreen
[polgarath@gmail.com]
Sent: 16 December 2011 00:01
To: mems-talk@memsnet.org
Subject: [mems-talk] AZ9260 thick film resist

Hi,

I've been trying for months now to achieve a positive resist (AZ9260)
thickness of >50 microns on a Au-coated Si substrate. I tried
double-spinning it, but only achieved a thickness of 20 microns at best.

Could I please be advised on my recipe?

Recipe for each spin:
Steps: 1,2,3
RPM: 500, 250, 10
Ramp: 15.1, 5.0, 1.0
Dwell: 30, 30, 1

I baked the first spin for 5 mins and the second spin for 10 mins @ 110 deg
celsius

Should I increase my ramp and lower my dwell? Microchem suggests a ramp of
900rpm/s and an RPM of 1.500 rpm for 3s. Just to check, 1.500 rpm really
refers to 1500RPM? I'm confused by the use of decimal here, and my
spincoater isn't able to reach a ramp anywhere near 900 rpm/s. I'm truly at
a loss.

In addition, my rehydrated samples don't develop well as compared to those
that I expose immediately. However, the ones that I expose immediately
develop well, but appear cracked after a few days - could it be due to the
uneven rate of expanding caused by the diffusion of water into the samples?
I did not keep them somewhere airtight.

Many thanks in advance!