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Study of roughness in multilayer Mo–Si mirrors
Author(s) -
Valkovskiy G. A.,
Baidakova M. V.,
Brunkov P. N.,
Konnikov S. G.,
Yagovkina M. A.,
Zadiranov Ju. M.
Publication year - 2011
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201184274
Subject(s) - x ray reflectivity , reflectometry , materials science , surface finish , optics , surface roughness , root mean square , scattering , substrate (aquarium) , sputter deposition , small angle x ray scattering , sputtering , thin film , composite material , nanotechnology , physics , geology , computer science , time domain , oceanography , quantum mechanics , computer vision
Abstract Combined approach based on X‐ray reflectometry (XRR), atomic‐force microscopy (AFM), and small‐angle X‐ray scattering (SAXS) has been applied to two series of multilayer Mo/Si mirrors grown by magnetron sputtering on standard and specially smoothed substrates under different technological conditions ( A and B ). Simulation of XRR data, using a model of two layers in period, can distinguish the mirror quality in terms of the total root mean square roughness. The quality is better for mirrors grown on smoother substrate, but it also depends on technological conditions. In addition, use of a model with transition layers reveals an asymmetry of Mo/Si and Si/Mo interfaces. Analysis of surface roughness PSD functions obtained by AFM shows that the surface diffusion is the dominant smoothing mechanism for all the mirrors studied. The low‐frequency roughness is conformal to that of the substrate for better mirrors (series A ), but increases for poorer quality mirrors (series B ). Simulation of SAXS data provides roughness parameters of the internal interfaces. For the better mirrors, the lateral correlation length of the roughness does not exceed 13 nm. However, this length is about 50 nm for the poorer quality mirrors, in agreement with AFM data.