Interface Characterization of Photonic Films Created by Plasma Enhanced Chemical Vapor Deposition (PECVD)

The structures of substrate/layer and layer/air interfaces in copolymer films made using PECVD have been probed for the first time using x-ray reflectivity (XR) and atomic force microscopy (AFM). Ellipsometry and XR measurements reveal that one can tune the visible light refractive index and XR refractive index by varying the monomer feed ratio in the copolymer films. Also, the structures of homopolymer octafluorocyclobutane (PP-OFCB) films made at different processing conditions were studied using XR and AFM. In addition to the narrow ``transition region'' next to the substrate, films deposited at power higher than 40 W exhibit structures adjacent to the air that differed from the structure in the ``center'' of the film. Uniform film structure can be achieved using any of three monomer feed locations. There are small differences between the structure deposited on 2'' diameter wafers and that deposited on 3'' diameter wafers, attributable to differences in flow dynamics.