Comparative study of carbon and boron carbide spacing layers inside soft x-ray mirrors

Tungsten, iron, and rhodium materials have been deposited alternatively with carbon and boron carbide by diode RF-sputtering. The multilayer performances have been measured at the carbon or boron K-alpha lines depending on the layer spacing. It is found that tungsten and iron provide multilayers with good optical quality and optimized layer densities. This is related to the amorphous character of the tungsten and iron layers which results in low intrinsic roughness and limited interdiffusion. The experimental reflectivity is a factor of 2/3 lower than the theoretical value for W/C multilayers at 44.7 A. Rhodium layers alternated with carbon are crystallized, which induces significant interface roughness and poor soft X-ray performances. It is concluded that boron-carbide-based multilayers always exhibit lower interface roughness than carbon-based ones.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.