A series of buried CoSi2 layers prepared by a modified molecular beam epitaxy process (allotaxy) and a subsequent wet-oxidation process was investigated by x-ray scattering. The oxidation time which determines the depth in which the CoSi2 layers are located within the Si substrates has been varied during the preparation. The electron density profiles and the structure of the interfaces were extracted from specular reflectivity and diffuse scattering measurements. Crystal truncation rod investigations yielded the structure on an atomic level (crystalline quality). It turns out that the roughness of the CoSi2 layers increases drastically with increasing oxidation time, i.e., with increasing depth of the buried layers. Furthermore, the x-ray data reveal that the oxidation growth process is diffusion limited. (C) 2000 American Institute of Physics. [S0021-8979(00)00901-4].