In this Faculty Early Career Development Award funded by the Advanced Materials Chemistry Program in the Chemistry Division, Ellen R. Fisher of Colorado State University will investigate plasma-enhanced chemical vapor deposition of thin films of silicon dioxide and hydrogenated amorphous silicon nitride films (alpha-SiNx:H). Critical reactions between gas-phase radical species and the surface being processed by an rf plasma will be studied using a modified IRIS (Imaging of Radicals Interacting with Surfaces) method which combines spatially-resolved laser-induced fluorescence (LIF) detection with molecular beam techniques. Radical reactivities will be measured in real time during thin film deposition. IRIS will enable radicals to be studied which desorb from a surface but are not in the incident molecular beam, yielding information about volatile products produced by surface reactions. Alkoxysilane plasma systems as well as SiX4/NH3 and SiX4/N2 plasmas will be examined. The reactivity of intermediates will be measured as a function of rf input power, radical rotational state, and substrate temperature. Silicon dioxide and silicon nitride films are widely used as gate oxides, passivation layers, and interlevel dielectrics for integrated circuits. Since the mechanisms for plasma deposition of these films is still unknown, further progress to improve film quality will be enhanced by understanding the underlying chemical processes involved, such as provided in this project.
