Roughness of molecularly thin perfluoropolyether polymer films

X-ray reflectivity has been used to measure the roughness of perfluoropolye ther (PFPE) polymer films on silicon substrates and carbon overcoats. For P FPE on smooth silicon, we find that the rms roughness of the PFPE-air inter face increases slowly from about 2 to 4 Angstrom as PFPE thickness increase s from 5 to 33 Angstrom. This increase is consistent with capillary waves r oughening the polymer film, but inconsistent with current theories for the dewetting of polymer films. For PFPE on the rougher surface of amorphous hy drogenated carbon, we find that the PFPE polymer smoothes the surface with the rms roughness decreasing from 9 to 4 Angstrom. We also discuss the impl ications of these results on the limits of disk drive technology. (C) 2000 American Institute of Physics. [S0003-6951(00)05046-4].