Refractive Index Profiles of Thermally Grown and Chemically Vapor Deposited Filmson Silicon

摘要

Ellipsometry, although used extensively in the microelectronics field for themeasurement of film thicknesses and refractive indices, does not usually yield reliable refractive indices for dielectric films less than 50 nm thick due to instrumental errors and software limitations. Addressing this issue, we report ellipsometric procedures that enable a reliable assessment of refractive index profiles for a variety of thermally grown and chemically vapor deposited, CVD, dielectric films on Si substrates down to about 10 nm thickness and we compare the results in terms of the current understanding about the film-substrate interface. In all cases studied we find that the interfacial region is optically different than the thick film, and that the precise film processing substantively alters the nature of the interface region. (kt)