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Method for fabricating reticles for EUV lithography without the use of a patterned absorber

Patent ·
OSTI ID:921903

Absorber material used in conventional EUVL reticles is eliminated by introducing a direct modulation in the complex-valued reflectance of the multilayer. A spatially localized energy source such as a focused electron or ion beam directly writes a reticle pattern onto the reflective multilayer coating. Interdiffusion is activated within the film by an energy source that causes the multilayer period to contract in the exposed regions. The contraction is accurately determined by the energy dose. A controllable variation in the phase and amplitude of the reflected field in the reticle plane is produced by the spatial modulation of the multilayer period. This method for patterning an EUVL reticle has the advantages of (1) avoiding the process steps associated with depositing and patterning an absorber layer and (2) providing control of the phase and amplitude of the reflected field with high spatial resolution.

Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA
Sponsoring Organization:
United States Department of Energy
DOE Contract Number:
W-7405-ENG-48
Assignee:
The Regents of the University of California (Oakland, CA)
Patent Number(s):
6,635,391
Application Number:
09/752,887
OSTI ID:
921903
Country of Publication:
United States
Language:
English

References (2)

Increase of multilayer x‐ray reflectivity induced by pulsed laser heating journal June 1994
Maskless extreme ultraviolet lithography
  • Choksi, Neha; Pickard, D. S.; McCord, Mark
  • Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, Vol. 17, Issue 6 https://doi.org/10.1116/1.590952
journal January 1999

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