Interdiffusion In Low-Temperature Annealed Amorphous Comon/Cn Compound Soft-X-Ray Optical Multilayer Mirrors

Interfacial interdiffusion in dual-facing-target sputtered amorphous CoMoN/CN soft-x-ray optical multilayer mirrors has been investigated quantitatively by monitoring the enhancement of the first-order modulation peak on annealing in the temperature range of 498-548 K. Smaller negative interdiffusivity is quite noticeable by comparing with those of Co/C and CoN/CN systems, signalling that relatively stable interfaces were formed by incorporation of molybdenum. Thermodynamic calculation reveals that the increase of binding enthalpy is the main factor leading to a larger activation energy and hence the smaller interdiffusion coefficient. The results imply that it is possible to further improve the thermal stability of CoN/CN multilayers by doping with refractory metals such as molybdenum.