Cleaning of Hydrocarbon Buildup on Metallic-oxide Thin-Films

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Cleaning of Hydrocarbon Buildup on Metallic-oxide
Thin-Films

• Richard Sandberg
• Ross Robinson, Dr. David Allred,
• Dr. R. Steven Turley, Aaron Jackson,
• Shannon Lunt, Elke Jackson, Kristi Adamson,
  Guillermo Acosta, Nick Webb, Mike Diehl, Luke
  Bissell
• Brigham Young University
• Department of Physics and Astronomy

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How to Stay Clean in an Unclean World?

• Determining Optical Properties for Ur, V, Sc
• Applications
• -Image satellites
• -Medical equipment
• -UV computer chip lithography
• We need to understand the optical properties of
  these materials in this region. EUV light is
  highly reactive to materialsa few Ångstrons of
  material greatly affect reflectivity.

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Lithography
XUV Microscopy
Multilayer Mirrors
XUV Astronomy
Images from www.schott.com/magazine/english/info99
/
www.lbl.gov/Science-Articles/Archive/xray-inside-c
ells.html
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Purpose What does hydrocarbon buildup do to
reflectance?How do we effectively remove
hydrocarbon buildup?Does this cleaning process
damage our thin films?

• Outline
• Effects of hydrocarbon Contamination buildup
• Opticlean Process
• Opticlean Residue
• Damage to thin films?
• Removing Opticlean Residue through plasma etching
• Conclusions

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Sample Creation

• Creation in vacuum chamber on silicon substrates
• RF Sputtering
• Evaporation
• We are working in high vacuum, but not Ultra high
  vacuum

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Reflectance goes down with hydrocarbon buildup in
the EUV
Produced on IMD Software
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A Clean Surface is Important

• EUV light is very reactive with materials,
  therefore, a few angstroms of contaminant will
  greatly reduce reflectivity.
• We expect to see the following decreases from
  initial reflectance due to buildup of 18 days
• 46 of initial reflectance due to leaving in
  ambient air
• (Corresponds to 20 Ångstroms of buildup)
• 36 of initial reflectance due to touching with a
  latex glove
• (Corresponds to 46 Ångstroms of buildup)

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Opticlean Process leaves hydrocarbon residue

• Opticlean significantly removes contaminants,
  but leaves a residue
• Ellipsometric Results
• Opticlean residue
• thickness on two runs
• 17 Ångstroms
• 22 Ångstroms
• Opticlean made by Dantronix Research and
  Technologies, LLC
• Ellipsometer Type J.A. Woollam Co., Inc
  Multi-Wavelength Ellipsometer (EC110)

http//www.dantronix.com
http//www.jawoollam.com/
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Does the Opticlean process damage thin films?

• Scanning Electron Microscope with EDAX showed no
  thin film damage, nor trace of materials used in
  thin films on pulled of Opticlean (U, Sc, Va).
• X-Ray Photoelectron Spectroscopy found no trace
  of materials used in thin films on pulled of
  Opticlean.

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XPS revealed components of Opticlean, but not
heavier metals used in thin films. Prominent
thin-film lines Ur-380 eV, V-515 eV, Sc-400 eV
527 eV (O 1s)
684 eV (F 1s)
281 eV (C 1s)
Photons (Counts)
97 eV (Si 2p)
148 eV (Si 2s)
Photon Energy (eV)
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Cleaning residue with Matrix Plasma Etch

• RF Plasma Etching with O2 Plasma
• 0.120 Torr Pressure
• 250W RF (max 350)
• 0.75 SCCM O2 flow
• No extra heat applied
• Good for removing polymers, but not bulk
  contaminants (i.e. Dust)
• Active Oxygen plus mechanical sputtering removes
  surface layers
• Used to clean Opticlean residue

RF
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Putting It All Together

• Samples cleaned with Opticlean to remove bulk
  contaminants without damaging sample.
• Opticlean residue was subsequently removed with
  Matrix Plasma Etch
• 23 Å residue left on surface
• 120 min. in O2 plasma
• Plasma removed 22 Å
• Hydrocarbon goo can effectively be removed with a
  two step cleaning process of Opticlean and Plasma
  Etching

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Thank You! Stay Clean!!
My Information Richard Sandberg BYU Department
of Physics and Astronomy (801)
368-7779 Rudyskaboy_at_Hotmail.com