Measurements of carbon thin films using x-ray reflectivity

We report x-ray reflectivity measurements on ultrathin (∼250 Å) amorphous carbon films and show that for film thicknesses of a few hundred angstroms this is an extremely effective, accurate, and nondestructive technique for measuring the thickness, density, and microscopic surface roughness. These properties are difficult to accurately measure using other methods. However, since they affect the functional performance of these films and are dependent on preparation conditions, their determination is particularly important.