Hi, all.
I am using the SPI critical point drying apparatus form PSI supplies (division
of Structure Probe, Inc.) to release comb-finger structures (0.5um wide, 0.5
um thick, and 10um long) on 1 um thick SiO2 on a Si substrate. I usually use
Buffered Oxide Etchant to remove SiO2 under comb-finger structures to be
released without any atiction problem. After I put my sample in the ample boat
with methanol, I load the boat into the critical point drying apparatus. Then
I flush with CO2 for about 3 minutes and wait for 30 minutes for methanol and
CO2 to be mixed well. And I do flusing agian for 3 minutes and the apparatus
is heated up above 35C with the pressure of more than 1300 psi. After I wait
for 10 minutes or so, I vent the CO2 gas.
But there is the point I have a problem. While I'm venting the CO2, I notice a
little haze generated and that can be seen by my own eyes.
After finishing the venting and taking out the sample, I noticed some parts
are o.k., but some parts, especially the end of suspended structurs, are stuck
to the substrate.
Please send me any processing tips to solve this problem.
Thanks.

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Sang Won Park
Graduate Research Assistant
Electrical Engineering
The University of Texas at Dallas
Phone) 972 - 883 - 2893
Fax) 972 - 883 - 6839