Hi Bernd, Thanks for your suggestion. The AZ patterns on my samples are around tens of micron, so, as you said the pattern will smear in nanometer scale, can I say it should not be a problem about that? It might be difficult for me to vacuum seal the samples because I need to use them at about few samples per week. From your experiences, does it make sense if I keep some desiccants in the package to keep them dry? Thanks, Yingtao -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of Krueger, Bernd Sent: 13 July 2009 08:20 To: General MEMS discussion Subject: [mems-talk] Storage of developed AZ photoresist Hi Yingtao, Unexposed AZ resist could be stored for more than 6 month when it is vacuum sealed. The same is true for exposed resist. Be carefull if you have very tiny pattern. Storage will smear a few nm and will end with the loss of sharp edges in any dimensions. We have tested 100nm lines and storage of 1h to 5d. If possible you can freeze the vacuum sealed material to decrease this effect. Reminder: to avoid moisture do not open package before it has reached room temperature. Regards, Bernd