Hello,

Regarding SEM based lithography, there are two widely used systems
available in the market today, NPGS and Raith. They have distinct
abilities but both can do nearly the same thing. Your resolution is set
by the microscope you choose. Almost all microscopes allow you to
control x-y, however a beam blanking option is required for some non
trivial lithography jobs. IF you NEED very tight control of corners and
other sharp geometries then you may, in some cases, need proximity
correction. This may limit your choice of system. Both systems mentioned
above have web sites, listed below.
Have fun.

  http://www.raith.de/Old.htm
  http://users.aol.com/jcnabity/npgs/index.htm

Dr. Roberto Panepucci
Device Research Lab
University of Campinas - Sao Paulo, Brazil
roberto@ifi.unicamp.br