TABLE OF CONTENTS Roughness, one aspect of surface structure, affects many aspects of thin films. As was discussed in Chapter II, roughness leads to porosity in zone a deposition. Roughness affects the magnetic properties of multilayer devices, the crystallographic texture of films, the properties of electronic devices, the effectiveness of gate dielectrics, the optical properties, etc. Hence, a discussion of the relationships between processing and surface roughness of thin films is justified in this chapter. Roughness is not the only characteristic of surface structure. The surface reconstruction of the lattice structure affects catalytic and other surface dependent properties of thin films as well as affecting the bulk defect structure of the deposited film. We have already noted that surface stress can and does affect the ordered arrangement of components of a multicomponent film. The attainment of peculiar configurations at surfaces, such as quantum dots and whiskers, both an expression of surface structure, also is of interest.
Among the origins of surface roughness of deposited films are a lack of sufficient adatom mobility, highly anisotropic surface energies favoring the formation of facets of low surface energy, highly anisotropic sticking coefficients on polycrystalline substrates, in energetic deposition differential resputtering of polycrystalline film surface, elastic strain energy in deposited film, etc. Thus, among the main processing procedures used to reduce surface roughness are, if possible, deposition or annealing at elevated temperature1 and use of low energy incident particles to provide adatom lateral displacement without resputtering or the introduction of defects.2 The effect...
