Significant improvement of electrical and thermal properties of low dielectric constant plasma polymerized paraxylene thin films by postdeposition H2+He plasma treatment

Electrical and thermal properties of plasma polymerized paraxylene (PPpX) thin films were significantly improved by postdeposition H2+He plasma treatment. Plasma treatment decreased dielectric constants and increased thermal stability. As the plasma treatment time increased from 0 to 6 min, the relative dielectric constant k decreased from 3.23 to 2.77. Suppression of C=O and O–H group formation and increase of C–H groups in the PPpX film were thought to contribute to the reduction of the k values. Plasma treatment enhanced the thermal stability of PPpX thin films. While the untreated PPpX thin film was stable only to 400 °C, plasma-treated films were stable up to 450 °C. H2+He plasma treatment did not increase the leakage current through the PPpX films notably and did not degrade the surface smoothness, either.