Structural transformations in Sc/Si multilayers irradiated by EUV lasers

Multilayer mirrors for the extreme ultraviolet (EUV) are key elements for numerous applications of coherent EUV sources such as new tabletop lasers and free-electron lasers. However the field of applications is limited by the radiation and thermal stability of the multilayers. Taking into account the growing power of EUV sources the stability of the optics becomes crucial. To overcome this problem it is necessary to study the degradation of multilayers and try to increase their temporal and thermal stability. In this paper we report the results of detailed study of structural changes in Sc/Si multilayers when exposed to intense EUV laser pulses. Various types of surface damage such as melting, boiling, shock wave creation and ablation were observed as irradiation fluencies increase. Cross-sectional TEM study revealed that the layer structure was completely destroyed in the upper part of multilayer, but still survived below. The layers adjacent to the substrate remained intact even through the multilayer surface melted down, though the structure of the layers beneath the molten zone was noticeably changed. The layer structure in this thermally affected zone is similar to that of isothermally annealed samples. All stages of scandium silicide formation such as interdiffusion, solid-state amorphization, silicide crystallization etc., are present in the thermally affected zone. It indicates a thermal nature of the damage mechanism. The tungsten diffusion barriers were applied to the scandium/silicon interfaces. It was shown that the barriers inhibited interdiffusion and increased the thermal stability of Sc/Si mirrors.

[1]  E. N. Zubarev,et al.  Materials Modification with Intense Extreme Ultraviolet Pulses from a Compact Laser , 2007 .

[2]  Fredrik Eriksson,et al.  14.5% near-normal incidence reflectance of Cr/Sc x-ray multilayer mirrors for the water window. , 2003, Optics letters.

[3]  Dong Nyung Lee,et al.  Transmission electron microscopy observations of Cu-induced directional crystallization of amorphous silicon , 2005 .

[4]  Atsushi Yamazaki,et al.  Development of an extreme ultraviolet imaging spectrometer for the BepiColombo mission , 2004 .

[5]  T. Tang,et al.  Experimental study of aluminum-induced crystallization of amorphous silicon thin films , 2005 .

[6]  L. Hultman,et al.  Crystallization Of Amorphous Silicon During Thin Film Gold Reaction , 1985 .

[7]  J. Feldhaus,et al.  Generation of high power femtosecond pulses by a sideband-seeded X-ray FEL , 2002 .

[8]  Florenta Costache,et al.  Modification of dielectric surfaces with ultra-short laser pulses , 2002 .

[9]  Sputtered V/Al2O3 multilayer X-ray mirrors for the water window , 2001 .

[10]  David L. Windt,et al.  Stress, microstructure, and stability of Mo/Si, W/Si, and Mo/C multilayer films , 2000 .

[11]  Heinz Sturm,et al.  Structure formation on the surface of indium phosphide irradiated by femtosecond laser pulses , 2005 .

[12]  Omar M. Knio,et al.  Numerical predictions of oscillatory combustion in reactive multilayers , 1999 .

[13]  Y. H. Zhang,et al.  Analysis of surface damage and plasma properties of pulsed laser ablation of GaAs , 2004 .

[14]  A. Singh,et al.  Laser damage studies of silicon surfaces using ultra-short laser pulses , 2002 .

[15]  J A Liddle,et al.  Nanoimaging with a compact extreme-ultraviolet laser. , 2005, Optics letters.

[16]  D Attwood,et al.  Reflection mode imaging with nanoscale resolution using a compact extreme ultraviolet laser. , 2005, Optics express.

[17]  H. Stollberga.  High-reflectivity Cr / Sc multilayer condenser for compact soft x-ray microscopy , 2006 .

[18]  G. Gorodetsky,et al.  Far UV pulsed laser melting of silicon , 1985 .

[19]  A. Freund.  Third-generation synchrotron radiation X-ray optics. , 1996, Structure.

[20]  Q. Xiao,et al.  A microbeam wavelength-dispersive x-ray fluorescence system and its application for thin-film analysis , 2005 .

[21]  J J Rocca,et al.  Soft-x-ray laser interferometry of a pinch discharge using a tabletop laser. , 1999, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[22]  H. W. Bergmann,et al.  Physical and material aspects in using visible laser pulses of nanosecond duration for ablation , 1996 .

[23]  John F Seely,et al.  Skylab 3600 groove/mm replica grating with a scandium-silicon multilayer coating and high normal-incidence efficiency at 38-nm wavelength. , 2002, Applied optics.

[24]  Erik H. Anderson,et al.  Nanometer-scale imaging with compact soft x-ray lasers , 2005, SPIE Optics + Photonics.

[25]  Chunlei Guo,et al.  Formation of extraordinarily uniform periodic structures on metals induced by femtosecond laser pulses , 2006 .

[26]  Timothy P. Weihs,et al.  Microstructural study of an oscillatory formation reaction in nanostructured reactive multilayer foils , 2005 .

[27]  D Sertore,et al.  Generation of GW radiation pulses from a VUV free-electron laser operating in the femtosecond regime. , 2002, Physical review letters.

[28]  Benjawan Kjornrattanawanich,et al.  Terbium-based extreme ultraviolet multilayers. , 2005, Optics letters.

[29]  Y. A. Unspenskii,et al.  Generation and application of a high-average-power polarized soft-x-ray laser beam , 2001 .

[30]  L. Golub,et al.  A new view of the solar corona from the transition region and coronal explorer (TRACE) , 1999 .

[31]  Torsten Feigl,et al.  Enhanced reflectivity and stability of Sc/Si multilayers , 2004, SPIE Optics + Photonics.

[32]  V. Kondratenko.  Periodic Multilayers MoSi2/Si with a Large Number of Periods , 1998 .

[33]  C S Menoni,et al.  Nanometer-scale ablation with a table-top soft x-ray laser. , 2006, Optics letters.

[34]  J. P. Hayes,et al.  Boron-Carbide Barrier Layers in Scandium-Silicon Multilayers , 2004 .

[35]  T. Efthimiopoulos,et al.  Laser ablation rate of materials using the generated acoustic waves , 1998 .

[36]  Igor A. Artyukov,et al.  Carbon window soft x-ray imaging using multilayer optics , 2005, SPIE Optics + Photonics.

[37]  Robert Sinclair,et al.  The preparation of cross‐section specimens for transmission electron microscopy , 1984 .

[38]  E. Gullikson,et al.  Soft X-ray reflectivity and structure evaluation of Ni/C/Ti/C multilayer X-ray mirrors for water-window region , 2001 .

[39]  E. A. Shamov,et al.  Multilayer dispersion optics for X-ray radiation , 2000 .

[40]  E. N. Zubarev,et al.  Damage to extreme-ultraviolet Sc/Si multilayer mirrors exposed to intense 46.9-nm laser pulses. , 2004, Optics letters.

[41]  Andrew G. Glen,et al.  APPL , 2001 .

[42]  S. Wagner,et al.  Amorphous silicon crystallization and polysilicon thin film transistors on SiO2 passivated steel foil substrates , 2001 .

[43]  R. Follath.  Design of FEL-Beamlines for Short Pulse, High Resolution and High Power Density , 2007 .

[44]  B. Clemens,et al.  Stress evolution in Mo/Si multilayers for high-reflectivity extreme ultraviolet mirrors , 1998 .

[45]  Dietmar Hirsch,et al.  Mo/Si multilayers for EUV lithography by ion beam sputter deposition , 2003 .

[46]  Anatoli I. Fedorenko,et al.  Thermally induced structural and phase transformations of Mo-Si and MoSi2-Si x-ray multilayer mirrors , 1995, Other Conferences.

[47]  Francesco Flora,et al.  Measurements of energy fluctuations of a saturated 46.9nm Ar laser produced in Z-pinch capillary discharges , 2005 .

[48]  David C. Eder,et al.  Investigation of Damage to Multilayer Optics in X-Ray Laser Cavities: W/C, WRe/C, WC/C, Stainless-Steel/C, and Cr3C2/C Mirrors. , 1992, Journal of X-ray science and technology.

[49]  Analysis of 46.9-nm Pulsed Laser Radiation Aftereffects in Sc/Si Multilayer X-Ray Mirrors , 2007 .