CD control is probably the most critical step in the building of an MOS
device. The less variation you have between your photo CD and the final After
Etch CD the better. Assuming your etch process produces an anisotropic etch
profile of the polysilicon you can expect the variation you get before etch to
be
reproduced in your after etch CD's. That is why lots of money have been
invested in photoresists,anti-reflective coatings and a variety of exposure
systems to make the photo CD's as uniform as possible.What you are trying to
reproduce as far as an image is concerned will merit a variety of choices for
resist. An example would be if you are trying to image a reflective surface like
Aluminum. It is best to use an ARC under the photoresist so that reflecting
light doesn't interfere with your CD within the wafer. Does this  help?   Bob
Henderson