Method of improving an x-ray lithography beamline uniformity

Abstract

A method is provided for calibrating a beamline (24) used for X-ray lithography. The beamline includes an elongated evacuated tube (28) extending from an X-ray source (22) for containing the X-ray beam to a closure (32) at an opposite end including a beryllium window. A target wafer (34) aligned with, but external of, the tube is positioned in a plane transverse of the X-ray beamline and is coated with a uniform layer of light sensitive material. A carbon filter (31) intermediate the X-ray source and the target wafer is provided within the tube to block electromagnetic radiation having wavelengths generally in the region of ultraviolet, visible, and infrared ranges of the spectrum. The beam from the X-ray source is scanned through the beamline, through the filter, and onto the target wafer. Thereafter, the wafer is subjected to an etch process thereby forming a contoured surface (34A) emulating the non-uniformities caused by the components of which the beamline is comprised. In a further step, at least one additional layer of filter material is applied to the surface of the carbon filter resulting in a modified carbon filter (31A) having a surface contour which is an inverse image of the surface contour of the target wafer. By so doing, undesired anomolies of X-ray radiation are avoided at the target wafer.