For manufacturing a radiation window for an X-ray measurement apparatus, an etch stop layer is first produced on a polished surface of a carrier. A thin film deposition technique is used to produce a boron carbide layer on an opposite side of the etch stop layer than the carrier. The combined structure including the carrier, the etch stop layer, and the boron carbide layer is attached to a region around an opening in a support structure with the boron carbide layer facing the support structure. The middle area of carrier is etched away, leaving an additional support structure.