title: Control of interface nanoscale structure created by plasma-enhanced chemical vapor deposition.
abstract: Tailoring the structure of films deposited by plasma-enhanced chemical vapor deposition (PECVD) to specific applications requires a depth-resolved understanding of how the interface structures in such films are impacted by variations in deposition parameters such as feed position and plasma power. Analysis of complementary X-ray and neutron reflectivity (XR, NR) data provide a rich picture of changes in structure with feed position and plasma power, with those changes resolved on the nanoscale. For plasma-polymerized octafluorocyclobutane (PP-OFCB) films, a region of distinct chemical composition and lower cross-link density is found at the substrate interface for the range of processing conditions studied and a surface layer of lower cross-link density also appears when plasma power exceeds 40 W. Varying the distance of the feed from the plasma impacts the degree of cross-linking in the film center, thickness of the surface layer, and thickness of the transition region at the substrate. Deposition at the highest power, 65 W, both enhances cross-linking and creates loose fragments with fluorine content higher than the average. The thickness of the low cross-link density region at the air interface plays an important role in determining the width of the interface built with a layer subsequently deposited atop the first.
authors.affiliation: Institute of Polymer Science and Polymer Engineering, The University of Akron, 170 University Avenue, Akron, Ohio 44325-3909, United States.
authors.forename: Someswara R
authors.initials: SR
authors.lastname: Peri
authors.forename: Bulent
authors.initials: B
authors.lastname: Akgun
authors.forename: Sushil K
authors.initials: SK
authors.lastname: Satija
authors.forename: Hao
authors.initials: H
authors.lastname: Jiang
authors.forename: Jesse
authors.initials: J
authors.lastname: Enlow
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Bunning
authors.forename: Mark D
authors.initials: MD
authors.lastname: Foster
mesh_terms: D017402:Chlorofluorocarbons; D005617:Chlorofluorocarbons, Methane / Q000737:chemistry; D005461:Fluorine / Q000737:chemistry; D005740:Gases / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D011108:Polymers / Q000737:chemistry; D005466:Fluorocarbons
chemical_list: D017402:Chlorofluorocarbons; D005617:Chlorofluorocarbons, Methane; D005461:Fluorine; D005740:Gases; D011108:Polymers; C007785:octafluorocyclobutane; D005466:Fluorocarbons