High-resolution synchrotron X-ray reflectivity study of the density of plasma-treated ultra low-k films

The density changes of porous SiLK (p-SiLK) organic dielectric films were studied by X-ray reflectivity technique. Blanket films on Si were studied under different plasma etch conditions, that are conventionally used in the etch processes of interconnects. X-ray reflectivity measurements were performed using a high-resolution Huber diffractometer and monochromatic 8.048 keV photons at the Singapore Synchrotron Light Source (SSLS). The results show that un-treated (as-grown) films are of good quality in terms of surface and interface roughness. All of the plasma-treated films keep their density (within 1-3% error), whereas the surface roughness increases and layer thickness decreases accordingly. The surface roughness is severely increased by oxidation for oxygen plasma-treated samples.