Access of Plasma Polymerization and Plasma Induced Vapor Phase Grafting Processes to High Aspect Ratio Trenches in Polymeric Microstructures Analyzed by XPS

Abstract

AbstractSummary: The results of scanning XPS investigations are reported. These were performed to investigate the access of different plasma processes to high aspect ratio trenches. Polystyrene test specimens containing special trench structures were treated by plasma polymerization or by plasma induced vapor phase grafting of allylamine. Highly resolved C1s peak spectra and the ratio of the nitrogen peak areas to the basic CHx peak were analyzed. Pulsed microwave and pulsed RF plasma polymerization of allylamine resulted in different inhomogeneous nitrogen content distributions on the side walls of the trenches. A depletion of the nitrogen content was observed for both processes. For the microwave process, the nitrogen content was also influenced by the aspect ratio, which varied from 2 to 10 for a trench depth of 3.5 mm. At the expense of chemical uniformity, a high N/C value was obtained by the pulsed MW plasma process. Vapor phase grafting of allylamine created inner surface functionalization which was rather uniform in terms of chemical composition and thickness.Scheme showing the analyzed part of the test specimen. It presents the side walls of the trench for measurement. The position of highly resolved C1s peak measurements is indicated as an open circle.imageScheme showing the analyzed part of the test specimen. It presents the side walls of the trench for measurement. The position of highly resolved C1s peak measurements is indicated as an open circle.