Stress compensated Si-membranes for x-ray masks

We report on X-ray transparent supporting membranes consisting of a simultaneously B and Ge doped epitaxial Si layer. The stress in the membranes induced by the high B doping can be adjusted to a desired level or even compensated by additional Ge incorporation. The properties of such stress compensated membranes and of only B doped ones are compared. The features of interest are tensile stress, optical transparency, curvature of wafer and membrane, and the lateral distortion of absorber patterns caused by wafer thinning.