In the ebeam lithography with PMMA resists isopropanol is often used in a mixture 3:1 (IPA:MIBK) as a developer solution. To my knowledge the developing process is usually stopped by putting the sample in distilled water and drying it with a nitrogen airgun. But I also see collegeaus who use the 3:1 mixture for developing and then "stop" the development in pure IPA. I actually think they develop further, as I know some people also use pure IPA instead of 3:1 mixture for developing.
What am I missing, I know there many different recipes in lithography, but this IPA thing doesn't make sense to me, using IPA as a stopper means to me the developing process is strengthened further and the resist isotropically resolved, which you normally want to avoid with kind of written sharp edged rectangular structures written by ebeam