Accession Number : ADP008034

Title :   Optimization of Growth Conditions of Vapor Deposited Mo/Si Multilayers,

Corporate Author : ARIZONA STATE UNIV TEMPE DEPT OF PHYSICS

Personal Author(s) : Stearns, M.B. ; Stearns, D.G.

Report Date : 05 MAR 1992

Pagination or Media Count : 2

Abstract : The dependence of the layer structure and interfaces of e-beam deposited Mo/Si multilayers (ML) on the growth conditions has been studied. The substrate temperature was varied over a range of 300-600 deg K at deposition rates of 1 and 3 A/sec. The structure of the ML was determined using small-angle x-ray scattering, large-angle x-ray scattering, and cross-sectional high-resolution electron microscopy. The variation of the normal incidence reflectivity was measured as a function of soft x-ray wavelength using synchrotron radiation. We found that the ML structure has a strong dependence on the substrate temperature and a lesser dependence on the deposition rate. ML grown at a substrate temperature of 300 deg K have Mo layers composed of small crystallites and exhibit significant short wavelength roughness. The lateral extent of the Mo crystallites increases and the interfacial roughness decreases with increasing substrate temperature up to 525-550 deg K. We attribute the larger Mo crystallites, improved texture and suppression of columnar growth observed at higher substrate temperatures to the increased surface mobility of the adatoms. The optimum conditions to obtain smooth layers by e-beam deposition were found to be a substrate temperature of approx. 525 deg K and a deposition rate of approx. 1 A/sec. Thus to a great extent the smaller adatom energies of e-beam deposition can be compensated for by increasing the substrate temperature. Above T sub s approx. 575 deg K interdiffusion is observed to significantly degrade the ML structure.

Descriptors :   *SOFT X RAYS, *ELECTRON BEAMS, *VAPOR DEPOSITION, ADATOMS, DEPOSITION, ELECTRON MICROSCOPY, HIGH RESOLUTION, INTERFACES, LAYERS, MICROSCOPY, RADIATION, REFLECTIVITY, ROUGHNESS, SHORT WAVELENGTHS, SILICON, STRUCTURES, SUBSTRATES, SUPPRESSION, SURFACES, SYNCHROTRON RADIATION, TEXTURE, X RAY SCATTERING, X RAYS, HIGH ANGLES, LOW ANGLES.

Subject Categories : Optics
      Nuclear Physics & Elementary Particle Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE