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 RIE2 Wet Polymer Etch
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. RIE2 can etch polymers in almost the same way as the ASE. We prefer the you use the ASE but there can be situations where the sample will not be allowed in the ASE (e.g. if there are metal on). If you think you need to use the RIE2 for polymer etching you need to get a special permission from the plasma group, see contact info on the RIE2 page in LabManager. 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

Process dependent:
Almost isotropic to anisotropic (vertical to sample surface)

Isotropic

Possible etch reactants
  • Oxygen plasma
  • Oxygen plasma mixed with
    • CO2
    • SF6
    • Ar
  • Oxygen plasma
  • Oxygen plasma mixed with
    • N2
    • CF4
  • Oxygen plasma
  • Oxygen plasma mixed with
    • N2
  • Oxygen plasma
  • Oxygen plasma mixed with
    • CF4
    • SF6
    • N2
  • The different solvents available at Danchip, 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
  • Samples smaller that can fit on a 100mm wafer.
  • #1 50 mm wafer
  • #1 100 mm wafer
  • #1 150 mm wafer (only when the the system is set up for 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

Polymer wafers?

  • Si, SiO2, Si3N4
  • Glass
  • Metals (no Pb or Te)
  • Resists, polymers
  • Si, SiO2, Si3N4
  • Glass
  • Resists, polymers

Silicon wafers with layers of

  • Silicon oxide or silicon (oxy)nitride
  • Photoresist/e-beam resist
  • PolySilicon
  • Metals (no Pb and Te) max 5% wafer coverage
  • Clean Polymers

Quartz/fused silica wafers

Polymer wafers (only with special permission)

  • Any material that may go into the beaker used.