Hi Tony, Thanks for your suggestion. It is very helpful and I'm gonna try on it. I have one more small question. Do you bake the wafer piece after USB in methanol or you just directly spin adhesion promoter or PR after this step? Thanks, Li. Zhang --------- Graduate Student Edward P. Fitts Department of Industrial and Systems Engineering North Carolina State University Raleigh, NC 27695-7906 USA TEL: (919) 413-5459 Email: lzhang13@ncsu.edu Web: http://www.ise.ncsu.edu http://www.nnf.ncsu.edu