Specific Process Knowledge/Etch/Etching of Polymer

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Etching of Polymer

Stripping of polymer is often done by wet chemistry in a solvent that dissolves the given polymer. If wet chemistry cannot be used or a more controlled etch of the polymer is needed a plasma system is used instead. Plasma ashers are designed for removing polymers in primarily oxygen plasmas. It you need a more directional etch with a masking material RIE2 or ASE can be used.




Comparison of methods for polymer etching

ASE Plasma asher 1 Plasma asher 2 Wet Polymer stripping
General description The ASE was originally a dedicated deep Si etcher, but with the arrival of the Pegasus it has now been opened for polymer etching. The plasma asher is good for dry stripping polymers. It can also be used for descum and pattering of polymers. The plasma asher is good for dry stripping polymers. It can also be used for descum and pattering of polymers. This plasma asher is for Si wafers without metals. Wet polymer etching is used for stripping a resist/polymer when it is no longer needed. E.g. removing resist masks.
Etch direction

Process dependent:
Isotropic to anisotropic (vertical to sample surface)

Isotropic

Isotropic

Dissolves the polymer

Possible etch reactants
  • Oxygen plasma
  • Oxygen plasma mixed with
    • SF6
    • CF4
    • Ar
  • Oxygen plasma
  • Oxygen plasma mixed with
    • N2
    • CF4
  • Oxygen plasma
  • Oxygen plasma mixed with
    • N2
  • The different solvents available at Nanolab, such as
    • Acetone
    • 1165 Remover
Substrate size
  • Samples smaller than 100 mm wafers must be glued to a 100 mm wafer or placed in a reces on a 100 mm wafer.
  • #1 100 mm wafer
  • #1 150 mm wafer (only when system is set up for 150 mm wafers)
  • Several small samples
  • #25 50 mm wafers
  • #25 100 mm wafers
  • #25 150 mm wafer
  • Several small samples
  • #25 50 mm wafers
  • #25 100 mm wafers
  • #25 150 mm wafers
  • Any sample # and size that can go into the beaker used.
Allowed materials

Silicon wafers with layers of

  • Silicon oxide or silicon (oxy)nitride
  • Photoresist/e-beam resist
  • PolySilicon
  • Aluminium
  • Polymers (list?)
  • Quartz/fused silica wafers
  • Metals (no Pb and Te) max 5% wafer coverage

Polymer wafers?

  • Si, SiO2, Si3N4
  • Glass
  • Metals (no Pb or Te)
  • Resists, polymers
  • Si, SiO2, Si3N4
  • Glass
  • Resists, polymers
  • Any material that may go into the beaker used.