In situ measurement of roughness spectra using diffuse scattering

The in situ measurement of surface roughening is important to the characterization or control of a variety of dynamic processes, including polishing, etching, film growth, strain relaxation, phase transitions and interdiffusion. Solid and liquid surface roughness statistics are being studied using optical, x-ray, electron and atom diffraction. Whilst average roughness can be measured by specular scattering of x-rays, for example, only non-specular, diffuse diffraction can detect lateral correlations in atomic scale roughness and quantify the surface height-height correlation function or power spectral density function in real time. In this paper, the capabilities and application of diffuse diffraction of photons for in situ measurement of roughening statistics will be reviewed.