Hi Anirban,

Please look at my remarks within the quote of your mail.


        
        
        > **** Is it necessary to provide some sort of rehydration time
        > before exposure?


Yes. I'd say at least 30 min.

        
        > Problem #1: I have varying linewidths in my patterns ranging
        > from 10um (min) to 100um(max). I have no problems in getting
        > the bigger patterns OK but the smaller patterns of 10um
        > linewidth are not following the mask.  Most of the square
        > patterns came out closely to circle as well ovals mostly.
        >


You will always have problems in creating good 10µm structures in 20 µm
thick AZ4620. AZ4620 has a relatively small contrast and hence
a small sidewall angle. Try a resist with less absorption and
higher contrast

        > Problem#2:  I have to use this thick photoresist for Copper
        > electroplating. From my previous experiments I can see that
        > the smaller patterns are getting washed away after a certain
        > period of time in the electroplating solution.  The bigger
        > patterns are holding up well and I am able to get reasonably
        > good metal deposition.


Are you using a adhesion promoter like HMDS?

        > ****Do I need to hard bake the resist before performing the
        > electroplating?
        > If so what is the temperature which has to be used for this purpose?


To my knowledge hard bake is more improtant for etching rather than plating

        > Also if I am aiming for thick PR mold is double coating with
        > AZP4620 is a safe option or should I switch to  another
        > positive resist ( I cannot use negative resist like Su8) like
        > AZ92XX for the purpose.


Yes, to me AZ92xx would be a better choice.



Marc Hennemeyer
_________________________________
Application Engineer
SUSS MicroTec Lithography GmbH