Periodic Variation of Stress in Sputter Deposited Si/WSi2 Multilayers

A tension increment after sputter deposition of 1 nm of WSi2 onto sputtered Si was observed at low Ar gas pressures. Wafer curvature data on multilayers were found to have a periodic variation corresponding to the multilayer period, and this permitted statistical analyses to improve the sensitivity to small stresses. The observation of tension instead of compression in the initial stage of growth is new and a model invoking surface rearrangement is invoked. The data also bear on an unusual surface smoothing phenomena for sputtered Si surfaces caused by the sputter deposition of WSi2 . We furthermore report that for low Ar pressures the Si layers are the predominant source of built-up stress

Pressure-dependent transition from atoms to nanoparticles in magnetron sputtering: Effect on WSi2 film roughness and stress

We report on the transition between two regimes from several-atom clusters to much larger nanoparticles in Ar magnetron sputter deposition of WSi2, and the effect of nanoparticles on the properties of amorphous thin films and multilayers. Sputter deposition of thin films is monitored by in situ x-ray scattering, including x-ray reflectivity and grazing incidence small angle x-ray scattering. The results show an abrupt transition at an Ar background pressure Pc; the transition is associated with the threshold for energetic particle thermalization, which is known to scale as the product of the Ar pressure and the working distance between the magnetron source and the substrate surface. Below Pc smooth films are produced, while above Pc roughness increases abruptly, consistent with a model in which particles aggregate in the deposition flux before reaching the growth surface. The results from WSi2 films are correlated with in situ measurement of stress in WSi2/Si multilayers, which exhibits a corresponding transition from compressive to tensile stress at Pc. The tensile stress is attributed to coalescence of nanoparticles and the elimination of nano-voids.Comment: 16 pages, 10 figures; v3: published versio

Takagi-Taupin Description of X-ray Dynamical Diffraction from Diffractive Optics with Large Numerical Aperture

We present a formalism of x-ray dynamical diffraction from volume diffractive optics with large numerical aperture and high aspect ratio, in an analogy to the Takagi-Taupin equations for strained single crystals. We derive a set of basic equations for dynamical diffraction from volume diffractive optics, which enable us to study the focusing property of these optics with various grating profiles. We study volume diffractive optics that satisfy the Bragg condition to various degrees, namely flat, tilted and wedged geometries, and derive the curved geometries required for ultimate focusing. We show that the curved geometries satisfy the Bragg condition everywhere and phase requirement for point focusing, and effectively focus hard x-rays to a scale close to the wavelength.Comment: 18 pages, 12 figure

Results of x-ray mirror round-robin metrology measurements at the APS, ESRF, and SPring-8 optical metrology laboratories

This paper presents the first series of round-robin metrology measurements of x-ray mirrors organized at the Advanced Photon Source (APS) in the USA, the European Synchrotron Radiation Facility in France, and the Super Photon Ring (SPring-8) (in a collaboration with Osaka University,) in Japan. This work is part of the three institutions' three-way agreement to promote a direct exchange of research information and experience amongst their specialists. The purpose of the metrology round robin is to compare the performance and limitations of the instrumentation used at the optical metrology laboratories of these facilities and to set the basis for establishing guidelines and procedures to accurately perform the measurements. The optics used in the measurements were selected to reflect typical, as well as state of the art, in mirror fabrication. The first series of the round robin measurements focuses on flat and cylindrical mirrors with varying sizes and quality. Three mirrors (two flats and one cylinder) were successively measured using long trace profilers. Although the three facilities' LTPs are of different design, the measurements were found to be in excellent agreement. The maximum discrepancy of the rms slope error values is 0.1 μrad, that of the rms shape error was 3 nm, and they all relate to the measurement of the cylindrical mirror. The next round-robin measurements will deal with elliptical and spherical optics.Lahsen Assoufid, Amparo Rommeveaux, Haruhiko Ohashi, Kazuto Yamauchi, Hidekazu Mimura, Jun Qian, Olivier Hignette, Tetsuya Ishikawa, Christian Morawe, Albert Macrander, Ali Khounsary, and Shunji Goto "Results of x-ray mirror round-robin metrology measurements at the APS, ESRF, and SPring-8 optical metrology laboratories", Proc. SPIE 5921, Advances in Metrology for X-Ray and EUV Optics, 59210J (16 September 2005); https://doi.org/10.1117/12.623209.Optics and Photonics 2005, 2005, San Diego, California, United State

Takagi–Taupin dynamical X-ray diffraction simulations of asymmetric X-ray diffraction from crystals: the effects of surface undulations

Dynamical X-ray diffraction simulations from crystals with surface undulations are reported. The Takagi–Taupin equations are applied and used to derive results in good agreement with experimental data reported in a separate paper [Macrander, Pereira, Huang, Kasman, Qian, Wojcik &amp; Assoufid (2020). J. Appl. Cryst. 53, 789–792]. The development of Uragami [J. Phys. Soc. Jpn, (1969), 27, 147–154] is followed. Although previous work by Olekhnovich &amp; Olekhnovich [Acta. Cryst. (1980), A36, 22–27] treated a crystal in the shape of a round cylinder, there do not seem to be any reports of previous dynamical X-ray diffraction treatments specifically for surface undulations. The significance of the present work is that it bridges the diffraction treatment of more classical dynamical diffraction theory, which assumes a flat surface, and the simple kinematic diffraction theory. The kinematic theory has, to date, been the primary means of simulating X-ray diffraction from surfaces.</jats:p