Abstract

Structural, phase and chemical stabilities of multilayers Mo-Si, MOSi₂- Si, W-Si, WSi₂-Si, Cr-Sc, W-Sc, Mo-B₄C, Mo−(B+C), Mo₂B₅-B₄C, Cr₃C₂-C, TiC-C, Ti-Be and others were studied in 300-1100°C temperature range by small-angle and large-angle X-ray diffraction scattering and electron microscopy methods. The structural instability (crystallization of amorphous Si, C, MOSi₂, WSi₂, MoC, MoB₂, Mo₂B₅, B and Cr₃ C₂ and recrystal-lization of polycrystal Mo, W, Sc, MoSi₂, WSi₂, Mo₂B₅ and MoC layers) as well as the phase instability (transformation of MoSi₂ lattice from hexagonal to tetragonal modification) are responsible for the degradation of multilayers due to the development of the interface roughness and mechanical stresses. The chemical instability (formation of MoSi₂ and WSi₂ silicides at interfaces of Mo-Si and W-Si multilayers, Mo₂C and MoC carbides and MoB₂ and Mo₂B₅ borides in Mo-(B+C) multilayers, TiBe₁₂ in Ti-Be ones) influences critically chemical composition profile, layer thicknesses and a period of multilayers. Formation of chemical compounds accompanied by an amorphization of polycrystal layers (growth of amorphous Mo₂C and MoC carbides instead of polycrystal Mo at about 450 °C and the subsequent substitution of polycrystal molybdenum carbides on amorphous borides MoB₂ and Mo₂B₅ at 700-800 °C in Mo-(B+C) multilayers) promotes the smoothening of interfaces. This effect of the chemical instability can be used for an improving of the X-ray reflectivity of multilayers.

© 1994 Optical Society of America