ELLIPSOMETRY STUDY OF THE ADHESION OF DIELECTRIC THIN-FILMS ON POLYMER SUBSTRATES

The adhesion mechanisms of plasma-deposited silicon alloys on polymer substrates are studied by IR ellipsometry. The IR ellipsometer combine s the high sensitivity of Fourier transform spectroscopy with the fast modulation (37 kHz) of the phase-modulated ellipsometry technique. Th e film adhesion is characterized from the evolution of the vibrational properties of the polymer surface during the early stage of the film preparation. The influence of preliminary plasma treatments of the pol ymer surface is emphasized. Successive exposure of the polymer (polyca rbonate) to argon and (NH3, Ar) plasmas induces a substrate activation revealed by the appearance of CN bonds at the substrate surface. Then it is shown that the SiH4 plasma treatment leads to the formation of a very thin SiO(x) layer at the substrate surface. In particular, the enhancement of the film adhesion appears to be correlated with the pre sence of a vibration located at 1030 cm-1. The influence of the plasma conditions is also studied. In particular, the ion bombardment can en hance the film adhesion.