Method of improving an x-ray lithography beamline uniformity

A method of producing a modified carbon filter for calibrating a system used in X-ray lithography, the system comprising an X-ray source;

• a beamline including an elongated evacuated tube extending from the X-ray source to a closure at an opposite end including a beryllium window, the beamline operable for containing a beam of radiation from the X-ray source;
• a target wafer having a uniform surface thereon of light sensitive material, the target wafer being aligned with the beamline and spaced from the beryllium window and external of the beamline;
• a carbon filter within the elongated evacuated tube intermediate the X-ray source and the target wafer for blocking electromagnetic radiation having wavelengths generally in the region of ultraviolet, visible, and infrared ranges of the spectrum;
• and means for scanning the X-ray beam into a rectangular format for reception onto the target wafer, said method comprising the steps of:
• (a) providing the target wafer with a uniform layer of light sensitive material;
• (b) directing a beam from the X-ray source through the beamline and onto the target wafer positioned in a plane transverse of the X-ray beamline;
• (c) subjecting the wafer to an etch process so as to develop the pattern resulting from step (b) thereby forming a contoured surface emulating the non-uniformities caused by the components of which the beamline is comprised;
• (d) providing a carbon filter intermediate the X-ray source and the target wafer to block electromagnetic radiation having wavelengths generally in the region of ultraviolet, visible, and infrared ranges of the spectrum;
• and
• (e) applying to the surface of the carbon filter at least one additional layer of filter material resulting in a modified carbon filter having a surface contour which is in inverse proportion to the surface contour of the target wafer