The influence of working gas pressure on interlayer mixing in magnetron-deposited Mo/Si multilayers

Impact of Ar gas pressure (1−4 mTorr) on the growth of amorphous interlayers in Mo/Si multilayers deposited by magnetron sputtering was investigated by small-angle x-ray scattering (l=0.154 nm) and methods of cross-sectional transmission electron microscopy. Some reduction of thickness of the amorphous inter-layers with Ar pressure increase was found, while composition of the layers was enriched with molybdenum. The interface modification resulted in raise of EUV reflectance of the Mo/Si multilayer

Damage to extreme-ultraviolet Sc/Si multilayer mirrors exposed to intense 46.9-nm laser pulses

Includes bibliographical references (page 622).The damage threshold and damage mechanism of extreme-ultraviolet Sc/Si multilayer mirror coatings are investigated with focused nanosecond pulses at 46.9-nm radiation from a compact capillary-discharge laser. Damage threshold fluences of ~0.08 J/cm2 are measured for coatings deposited on both borosilicate glass and Si substrates. The use of scanning and transmission electron microscopy and small-angle x-ray diffraction techniques reveals the thermal nature of the damage mechanism. The results are relevant to the use of newly developed high-flux extreme-ultraviolet sources in applications

Structural transformations in Sc/Si multilayers irradiated by EUVlasers

Multilayer mirrors for the extreme ultraviolet (EUV) are keyelements for numerous applications of coherent EUV sources such as newtabletop lasers and free-electron lasers. However the field ofapplications is limited by the radiation and thermal stability of themultilayers. Taking into account the growing power of EUV sources thestability of the optics becomes crucial. To overcome this problem it isnecessary to study the degradation of multilayers and try to increasetheir temporal and thermal stability. In this paper we report the resultsof detailed study of structural changes in Sc/Simultilayers when exposedto intense EUV laser pulses. Various types of surface damage such asmelting, boiling, shockwave creation and ablation were observed asirradiation fluencies increase. Cross-sectional TEM study revealed thatthe layer structure was completely destroyed in the upper part ofmultilayer, but still survived below. The layers adjacent tothe substrateremained intact even through the multilayer surface melted down, thoughthe structure of the layers beneath the molten zone was noticeablychanged. The layer structure in this thermally affected zone is similarto that of isothermally annealed samples. All stages of scandium silicideformation such as interdiffusion, solid-state amorphization, silicidecrystallization, etc., are present in the thermally affected zone. Itindicates a thermal nature of the damage mechanism. The tungstendiffusion barriers were applied to the scandium/silicon interfaces. Itwas shown that the barriers inhibited interdiffusion and increased thethermal stability of Sc/Si mirrors

Structural transformation in C/Si multilayer after annealing

Amorphous C/Si multilayers were prepared by DC magnetron sputtering technique and investigated by transmission electron microscopy and low-angle x-ray diffraction methods after annealing at 650 and 950 °C. The amorphous interlayers of 0.5 − 0.6 nm thick were found at C/Si and Si/C interfaces being of different density and composition. Amorphous structure of the multilayer is stable up to 950 °C when crystallization of α-SiC occurs and voids form in α-Si layer.Изготовленные методом прямоточного магнетронного распыления аморфные многослойные композиции C/Si были исследованы методами просвечивающей электронной микроскопии и малоугловой рентгеновской дифракции после отжигов при температуре 650 и 950 °C. На границах раздела C/Si и Si/C обнаружены аморфные перемешанные зоны толщиной 0.5 – 0.6 нм c различными плотностью и составом. Аморфная структура многослойной композиции стабильна вплоть до 950 °C, когда наблюдается формирование пор в слоях α-Si и кристаллизация α-Si