Fabrication of Mo/Si multilayer mirrors for extreme ultraviolet lithography by means of superconducting bulk magnet magnetron sputtering

U. Mizutani, T. Yamaguchi, H. Ikuta, T. Tomofuji, Y. Yanagi, Y. Itoh, Tetsuo Oka

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The fabrication of a highly reflective multi-layer film is an urgent need in the next-generation extreme ultraviolet (EUV) lithography to print ever-smaller circuit patterns onto semiconductor wafers by using extremely short wavelength (13.5 nm) light. For this purpose, we have synthesized the Mo/Si multi-layer films by employing the two-cathode superconducting bulk magnet magnetron sputtering apparatus. The films were made by repeatedly depositing a pair of 4.5 nm thick Si and then 2.5 nm thick Mo layer up to 40 or 50 pairs on the Si wafer with its root-mean square (rms) surface roughness of 0.1 nm. The resulting rms surface roughness of the Mo/Si multi-layer film turned out to be 0.12 nm. The transmission electron microscope (TEM) studies revealed the inter-diffusion layer thicknesses of Si-on-Mo and Mo-on-Si layers to be 0.5 and 1.5 nm, respectively. The EUV-reflectivity was theoretically calculated to reach the value of 70%, when these structural data are inserted into the reflectivity formula. However, the highest EUV-reflectivity so far observed was 67% in the normal incident condition. The 2-3% shortage of the reflectivity is attributed to the presence of residual Xe gas atoms incorporated into the film during deposition in the reduced Xe gas atmosphere.

Original languageEnglish
Pages (from-to)1456-1460
Number of pages5
JournalPhysica C: Superconductivity and its Applications
Volume468
Issue number15-20
DOIs
Publication statusPublished - 2008 Sep 15
Externally publishedYes

Fingerprint

Extreme ultraviolet lithography
Magnetron sputtering
Magnets
Multilayer films
magnetron sputtering
Multilayers
magnets
lithography
mirrors
Fabrication
fabrication
reflectance
Gases
Surface roughness
surface roughness
wafers
Cathodes
Electron microscopes
residual gas
Semiconductor materials

Keywords

  • EUV lithography
  • Magnetron sputtering
  • Mo/Si multilayer
  • Superconducting bulk magnet

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

Cite this

Fabrication of Mo/Si multilayer mirrors for extreme ultraviolet lithography by means of superconducting bulk magnet magnetron sputtering. / Mizutani, U.; Yamaguchi, T.; Ikuta, H.; Tomofuji, T.; Yanagi, Y.; Itoh, Y.; Oka, Tetsuo.

In: Physica C: Superconductivity and its Applications, Vol. 468, No. 15-20, 15.09.2008, p. 1456-1460.

Research output: Contribution to journalArticle

Mizutani, U. ; Yamaguchi, T. ; Ikuta, H. ; Tomofuji, T. ; Yanagi, Y. ; Itoh, Y. ; Oka, Tetsuo. / Fabrication of Mo/Si multilayer mirrors for extreme ultraviolet lithography by means of superconducting bulk magnet magnetron sputtering. In: Physica C: Superconductivity and its Applications. 2008 ; Vol. 468, No. 15-20. pp. 1456-1460.
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