Fabrication of a grooved single-crystal X-ray analyzer

Silicon X-ray analyzer crystals were microfabricated by dicing and etching 10.3 cm (4-inch) diam., 1.35 mm thick, undoped float zone (111) silicon wafers. These analyzer crystals are intended for a beam line at the Advanced Photon Source synchrotron accelerator ring under construction at the Argonne National Laboratory. Parallel and perpendicular, 1 mm spaced grooves were cut on the silicon wafers using an automated dicing saw. The grooves were cut at 15 degree and 105 degree to the <110> primary flat to avoid crystallographic cleavage directions because mechanical strength was desired. The depth of the grooves was 1.15 mm, which was 85% of the wafer thickness. The two cutting parameters, progressive cutting thickness, and feed rate were optimized to reduce saw damage and chipping. Saw damage, which extended over a region of about 30 μm from grooves was removed by isotropic etching. The quality of the single crystal was tested by measuring the width to X-ray rocking curves with a double-crystal diffractometer. The best width was obtained with 11.2 arc-s. Since the ideal full width at half maximum (FWHM) according to X-ray dynamical diffraction theory is 9.7 arc-s, a broadening function with a FWHM of only 5.6 arc-s is present due to residual strains (quadrature addition is assumed)