Bragg{endash}Fresnel optics for hard x-ray microscopy: Development of fabrication process and x-ray characterization at the Advanced Photon Source
- Materials Research Laboratory, Materials Department and Physics Department, University of California, Santa Barbara, California 93106 (United States)
- National Nanofabrication Users Network (NNUN), Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States)
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
Results are presented on development of processes for fabricating linear and circular Bragg{endash}Fresnel lenses (BFLs) on Si and III{endash}V compound material substrates, and on x-ray characterization of linear BFLs at the Advanced Photon Source (APS). Processes were developed for fabricating long (zone length {gt}5 mm) linear BFLs on Si with enhanced capability for focusing high-energy x rays. By stitching together 20 sequentially exposed 400-{mu}m-long linear BFLs, we were able to fabricate 8-mm-long linear BFLs with 0.5-{mu}m finest zone width. BFLs were also fabricated on III{endash}V compound semiconductor substrates GaAs and InP, with improved process control due to the substantially reduced zone thickness required ({approximately}50{percent} less than Si). Reduction of the zone aspect ratio (thickness/width) lessens the demand on the process technology, and may lead to higher lens resolution and pattern transfer accuracy. A process was explored to fabricate BFLs on a GaAs/AlGaAs heterostructure incorporating a built-in {open_quotes}etch stop{close_quotes} layer to ensure uniform zone thickness. Experimental characterization of the focusing properties of a field-stitched 8-mm-long linear BFL on Si (zone aperture=150 {mu}m) was conducted at APS undulator beamline 1-ID-C using 10-keV x rays. Based on measured focal plane intensity distribution, the focus was estimated to be 1.2 {mu}m, comparable to the geometrically demagnified source size of {approximately}1 {mu}m. Lens efficiency was estimated to be {approximately}30{percent}. Work is underway to incorporate the BFL-microprobe in x-ray microdiffraction and fluorescence microscopy experiments to study spatially confined complex materials. {copyright} {ital 1998 American Institute of Physics.}
- OSTI ID:
- 639205
- Journal Information:
- Review of Scientific Instruments, Vol. 69, Issue 8; Other Information: PBD: Aug 1998
- Country of Publication:
- United States
- Language:
- English
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