Fabrication and tests of multilayer gratings for the soft X-ray region

Abstract

Mo/Si and Rh/C lamellar multilayer gratings for use above the silicon L edge and above the carbon Kalpha edge respectively were fabricated and characterized by soft X-ray reflectometry. The various gratings were made by photolithography or by electron beam lithography with a pitch ranging from 3 to 10 mu m and cyclic ratios (land to pitch) from 0.1 to 0.9. The Mo/Si gratings were etched down to the substrate in a fluorinated plasma. The Rh/C gratings were manufactured by coating multilayers on laminar gratings, of one hundred AA depth, etched into a carbon layer. The soft X-ray measurements were performed with synchrotron radiation. The diffraction spectra of the various samples were recorded in the grating and detector scan modes. In particular, the influence of the grating cyclic ratio on the diffraction spectra were investigated in the detector scan mode with Mo/Si gratings. The angular position of a great number of orders, recorded in the grating scan mode, is also discussed in the framework of a kinematical model.