EVOLUTION OF MORPHOLOGY IN AMORPHOUS AND CRYSTALLINE SILICON-CARBIDE SPUTTERED FILMS.

摘要

This thesis presents a detailed study of the development of morphology in noncrystalline (NC) and crystalline vapor-deposited films using silicon carbide (SiC) as a model system. Because of its refractory nature, SiC could be prepared as NC by rf-sputter deposition over a wide range of substrate temperatures (T(,s)) and the transition to highly crystalline films is gradual as T(,s) increases.;In NC films the aggregation leads to a continuously increasing cluster size as film thickness increases which reveals itself as parabolic-like film cross-sectional features. By increasing adatom mobility by increased T(,s), addition of reactive gas in the plasma, or increasing the energetic bombardment incident on the film surface, the parabolic function becomes steeper. In NC films, properties such as internal film stress and microhardness are found to vary proportionally to the bombardment experienced during deposition.;In crystalline and partially crystalline films the development of morphology is complicated by the competition between random clustering and crystallite aggregation as film thickness increases, and the modification of film properties by bombardment during deposition is more complicated.;In the present study NC, partially crystalline, and highly crystalline films display an anisotropic morphology which has been referred to as columnar in previous studies of vapor-deposited films. However, results of extensive scanning electron and transmission electron microscopy studies reveal several details that modify previous understanding of this morphology. In both NC and crystalline films, the columnar features were found to consist of aggregates of smaller units, random clusters in the case of NC films, and oriented or unoriented crystalline aggregates in the latter case, both surrounded by low density regions which define the columns.