Hydrogen induced blister formation in Mo/Si multilayer structures

Blister formation is explored in heterogeneous, layered materials composed of molybdenum-silicon layered structures. These can function as Bragg reflectors in the soft X-Ray or XUV optical range of the electromagnetic spectrum. Examples of these systems can be found in synchrotrons, telescopes and free electron lasers. In this thesis the formation of nanometre sized blisters in Mo/Si multilayer structures is investigated under the controlled exposure of low energy (<200eV) hydrogen ions and radicals. To be able to predict the conditions of blister formation, a model describing the growth and stability of hydrogen induced blisters by elastic deformation under hydrogen pressure was established. Experimentally observed blister sizes were compared with expected blister sizes from the blister model and good agreement was found. Besides hydrogen pressure, the influence of intrinsic stress in multilayers on the blister formation was investigated. It was found that increasing hydrogen pressure under the blister cap is the main cause of the observed blisters in the Mo/Si multilayers.