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Title: Silicide layer growth rates in Mo/Si multilayers

Abstract

The thermal stability of sputter-deposited Mo/Si multilayers was investigated by annealing studies at relatively low temperatures ([similar to]250--350 [degree]C) for various times (0.5--3000 h). Two distinct stages of thermally activated Mo/Si interlayer growth were found: a primary surge, followed by a (slower) secondary steady-state growth in which the interdiffusion coefficient is constant. The interdiffusion coefficients for the interlayer formed by deposition of Mo-on-Si are higher than those of the interlayer formed by deposition of Si-on-Mo. Assuming that the activation energy is constant, an extrapolation of our results to ambient temperature finds that interlayer growth is negligible, suggesting long-term thermal stability in soft-x-ray projection lithography applications.

Authors:
;  [1]; ;  [2];  [3];  [4]
  1. (Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States))
  2. (Department of Mechanical Engineering, Oregon State University, Corvallis, Oregon 97331 (United States))
  3. (Vernon Applied Physics, P.O. Box 10469, Torrance, California 90505 (United States))
  4. (Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States))
Publication Date:
OSTI Identifier:
5295150
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Optics; (United States); Journal Volume: 32:34
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; MOLYBDENUM; ANNEALING; SILICON; DIFFUSION; LAYERS; REFLECTIVITY; SOFT X RADIATION; SPUTTERING; TEMPERATURE RANGE 0400-1000 K; THERMODYNAMIC PROPERTIES; ELECTROMAGNETIC RADIATION; ELEMENTS; HEAT TREATMENTS; IONIZING RADIATIONS; METALS; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; RADIATIONS; SEMIMETALS; SURFACE PROPERTIES; TEMPERATURE RANGE; TRANSITION ELEMENTS; X RADIATION; 360104* - Metals & Alloys- Physical Properties; 360606 - Other Materials- Physical Properties- (1992-)

Citation Formats

Rosen, R.S., Stearns, D.G., Viliardos, M.A., Kassner, M.E., Vernon, S.P., and Cheng, Y.. Silicide layer growth rates in Mo/Si multilayers. United States: N. p., 1993. Web. doi:10.1364/AO.32.006975.
Rosen, R.S., Stearns, D.G., Viliardos, M.A., Kassner, M.E., Vernon, S.P., & Cheng, Y.. Silicide layer growth rates in Mo/Si multilayers. United States. doi:10.1364/AO.32.006975.
Rosen, R.S., Stearns, D.G., Viliardos, M.A., Kassner, M.E., Vernon, S.P., and Cheng, Y.. Wed . "Silicide layer growth rates in Mo/Si multilayers". United States. doi:10.1364/AO.32.006975.
@article{osti_5295150,
title = {Silicide layer growth rates in Mo/Si multilayers},
author = {Rosen, R.S. and Stearns, D.G. and Viliardos, M.A. and Kassner, M.E. and Vernon, S.P. and Cheng, Y.},
abstractNote = {The thermal stability of sputter-deposited Mo/Si multilayers was investigated by annealing studies at relatively low temperatures ([similar to]250--350 [degree]C) for various times (0.5--3000 h). Two distinct stages of thermally activated Mo/Si interlayer growth were found: a primary surge, followed by a (slower) secondary steady-state growth in which the interdiffusion coefficient is constant. The interdiffusion coefficients for the interlayer formed by deposition of Mo-on-Si are higher than those of the interlayer formed by deposition of Si-on-Mo. Assuming that the activation energy is constant, an extrapolation of our results to ambient temperature finds that interlayer growth is negligible, suggesting long-term thermal stability in soft-x-ray projection lithography applications.},
doi = {10.1364/AO.32.006975},
journal = {Applied Optics; (United States)},
number = ,
volume = 32:34,
place = {United States},
year = {Wed Dec 01 00:00:00 EST 1993},
month = {Wed Dec 01 00:00:00 EST 1993}
}
  • The thermal stability of sputter-deposited Mo/Si multilayers was investigated by annealing studies at relatively low temperatures ({approximately} 250--350 {degree}C) for various times (0.5--2000 h). Two distinct stages of thermally-activated interlayer growth were found: a primary surge'' of {approximately} 0.3 nm, followed by a (slower) secondary steady-state'' growth where the interdiffusion coefficient is constant. The interdiffusion coefficients for the interlayer formed by deposition of Mo-on-Si are 200 times greater than those of the interlayer formed by deposition of Si-on-Mo. The interdiffusion coefficient, D{sub o} {congruent} 100 cm{sup 2}/s and apparent activation energy, E{sub a} {congruent} 2.5 eV for the secondary stagemore » of Mo-on-Si interlayer growth are comparable to values for diffusion of Si in h-MoSi{sub 2}.« less
  • The thermal stability of sputter-deposited Mo/Si multilayers was investigated by annealing studies at relatively low temperatures ({approximately} 250--350 {degree}C) for various times (0.5--2000 h). Two distinct stages of thermally-activated interlayer growth were found: a primary ``surge`` of {approximately} 0.3 nm, followed by a (slower) secondary ``steady-state`` growth where the interdiffusion coefficient is constant. The interdiffusion coefficients for the interlayer formed by deposition of Mo-on-Si are 200 times greater than those of the interlayer formed by deposition of Si-on-Mo. The interdiffusion coefficient, D{sub o} {congruent} 100 cm{sup 2}/s and apparent activation energy, E{sub a} {congruent} 2.5 eV for the secondary stagemore » of Mo-on-Si interlayer growth are comparable to values for diffusion of Si in h-MoSi{sub 2}.« less
  • This study of the effect of implanted oxygen in the Si substrate was accomplished using an IR heating method and a combination of different materials analysis techniques. Principally, Auger electron spectroscopy combined with depth profiling was implemented to investigate the composition of the reacted metal-Si systems as well as the relative movement of the oxygen during silicide formation. The authors systematic study of these four metal-Si systems yielded some interesting results. First, for the three metals Mo, W, and Ti, we observed basically inhibited metal-Si reactions at laser processing conditions that yielded completely reacted metal silicides without implanted oxygen. Second,more » the evolution from inhibited reactions through partial, metal-rich silicides and finally to completely reacted metal silicide formation at high temperatures was observed and characterized. Last, a distinctly response to the presence of oxygen was observed for the Ti samples as compared to the Mo and W samples.« less
  • Multilayer structures of alternating thin layers of molybdenum and silicon are of great interest as x-ray optics components and a considerable amount of effort has been expended in their development. The efficiencies of these structures depend upon both the accurate control of the layer thicknesses and the sharpness in the interface between layers. High- resolution electron microscopy reveals that the interface created by deposition of Mo on Si is much more diffuse than that produced by depositing Si on Mo. We have used molecular dynamics to simulate the deposition processes and observe significant penetration of the Si substrates by themore » incident Mo atoms, while incident Si atoms remain on the surface of the Mo substrate.« less
  • Deposition of multilayers on saw-tooth substrates is a key step in the fabrication of multilayer blazed gratings (MBG) for extreme ultraviolet and soft x-rays. Growth of the multilayers can be perturbed by shadowing effects caused by the highly corrugated surface of the substrates, which results in distortion of the multilayer stack structure and degradation of performance of MBGs. In this study, to minimize the shadowing effects, we used an ion-beamsputtering machine with a highly collimated atomic flux to deposit Mo/Si multilayers on saw-tooth substrates. The sputtering conditions were optimized by finding a balance between smoothening and roughening processes in ordermore » to minimize degradation of the groove profile in the course of deposition and at the same time to keep the interfaces of a multilayer stack smooth enough for high efficiency. An optimal value of energy of 200 eV for sputtering Kr + ions was found by deposition of test multilayers on flat substrates at a range of ion energies. Two saw-tooth substrates were deposited at energies of 200 eV and 700 eV for the sputtering ions. It was found that reduction of the ion energy improved the blazing performance of the MBG and resulted in a 40% gain in the diffraction efficiency due to better replication of the groove profile by the multilayer. As a result of the optimization performed, an absolute diffraction efficiency of 28.8% was achieved for the 2nd blaze order of the MBG with a groove density of 7350 lines/mm at a wavelength of 13.5 nm. Lastly, details of the growth behavior of the multilayers on flat and saw-tooth substrates are discussed in terms of the linear continuous model of film growth.« less