Daniel, good question.  Here is my experience.  First the problems with resist
adhesion are usually caused by moisture and as the three vacuum purges with hot
nitrogen between the vacuum purges absolutely dehydrate the wafers, which is a
great start.  The HMDS molecule bonds to the wafer surface replacing the H in
the Hydroxyl ion with a Si(CH3)3 molecule, giving off ammonia.  This gives an
inorganic/organic molecule, bonded to the wafer.   The Three (CH3) atoms are on
the surface and there is not a chemical bond between the resist and the methyl
but the resist intertwines with the organic Methyl's for better adhesion.  So
you get a great bond at the wafer surface and a good interaction at the resist
face.  Experiments show a reduction in roughness of the resist/wafer Critical
Dimension from 0.8 microns +/- 10% down to 0.8 microns +/- 4%.  The 4% is the
roughness of the original resist line seen at the developed image.  If the
developed image can be improved the roughness of
 the finished line can be improved.  Bill


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