Effect of plasma deposited thin carbon layer on dielectric characteristics of Au-PI-Au structures

In this study, dielectric properties of a virgin polyimide (PI) sample and tailored PI sample are investigated in a metal-insulator-metal (MIM) structure comparatively. In order to modify the dielectric properties of the tailored sample, plasma enhanced chemical vapor deposition (PECVD) method was used, and a thin a-C:H layer was deposited on the sample surface. Then dielectric permittivity, dielectric loss and ac conductivity characteristics, which were calculated according to the measured capacitance, loss factor and conductance values, were plotted versus frequency (0.1-100 kHz) and temperature (20-300°C). Also, SEM images and FTIR spectrum of the samples were presented and evaluated. Consequently, a-C: H layer and accompanying plasma polymer interactions during PECVD led to decrease the permittivity of the sample, and increase the thermal stability of the tailored sample relatively.