In this investigation we apply the x-ray reflectivity and diffuse scatterin
g measurements to study the interface and surface morphology and bulk prope
rties of SiO2 amorphous films grown on Si substrates. Three samples with di
fferent interface and surface roughnesses are analysed. Simultaneous fittin
g of both specular reflectivity and diffuse scattering curves allows the de
termination of precise values of surface and interface roughness, film thic
kness and bulk density of silicon dioxide films. The distorted-wave Born ap
proximation is used for quantitative characterization of diffuse scattering
from the samples. The structural parameters obtained by the x-ray method a
gree with atomic force microscopy results.