NSF Award
9160568
The purpose of this work is to design x-ray optics for the collection and redistribution of the annular x-ray cone generated by transition radiation such that a uniform x-ray spot is delivered at high power density to a mask/wafer target. This will increase the power density from the existing 1 mW/cm2 to 5 mW/cm2 permitting transition radiation to be a competitive source for x-ray lithography. Transition radiation is emitted in conical annulus which has a central hole in the radiation pattern and more than half of the x-rays are emitted at angles larger than the angle of peak intensity. Hence, efficient collection of the x-rays and their proper collimation into a uniform beam area on the size of the mask and wafer target areas are required for uniform exposure of x-ray photoresist of microintegrated circuit production. We will demonstrate feasibility of using Kumakhov x-ray optics to collect and collimate x-rays from a transition radiation source over a angular range of up to + 30 mrad and to provide a quasiparallel beam suitable of x-ray lithography. The desired intensity uniformity across the output x-ray beam is 3% . A complete design of a Kumakohov lens based on computer simulation and on experimental results with single capillaries and polycapillaries and their correlation with theoretical predictions will be done.
