Specific Process Knowledge/Etch/Etching of Chromium

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Etching of Chromium

Etching of chromium can be done either by wet etch, dry etch or by sputtering with ions.


Comparison of Aluminium Etch Metodes

Al wet etch 1 Al wet etch 2 Al etch by ICP metal Al sputtering by IBE (Ionfab300+)
Generel description Wet etch of pure Al Wet etch of Al + 1.5% Si Dry plasma etch of Al Sputtering of Al - pure physical etch
Etch rate range
  • ~100nm/min (pure Al)
  • ~60nm/min (Al+1.5% Si)
  • ~350 nm/min (depending on features size and etch load)
  • ~30nm/min (not tested yet)
Etch profile
  • Isotropic
  • Isotropic
  • Anisotropic (vertical sidewalls)
  • Anisotropic (angles sidewalls, typical around 70 dg)
Substrate size
  • #1-25 100 mm wafers
  • #1-25 100 mm wafers
  • smaller pieces on a carrier wafer
  • #1 100mm wafers (when set up to 100mm wafers)
  • #1 150mm wafers (when set up to 150mm wafers)

Smaller pieces glued to carrier wafer

  • #1 50mm wafer
  • #1 100mm wafer
  • #1 150mm wafer
  • #1 200mm wafer
Allowed materials
  • Aluminium
  • Silicon
  • Silicon Oxide
  • Silicon Nitride
  • Silicon Oxynitride
  • Photoresist
  • E-beam resist
  • Aluminium
  • Silicon
  • Silicon Oxide
  • Silicon Nitride
  • Silicon Oxynitride
  • Photoresist
  • E-beam resist
  • Silicon
  • Quartz/fused silica
  • Photoresist/e-beam resist
  • PolySilicon,
  • Silicon oxide
  • Silicon (oxy)nitride
  • Aluminium
  • Titanium
  • Chromium
  • Silicon
  • Silicon oxides
  • Silicon nitrides
  • Metals from the +list
  • Metals from the -list
  • Alloys from the above list
  • Stainless steel
  • Glass
  • III-V materials
  • Resists
  • Polymers
  • Capton tape


Ething of Chromium can be done either wet or dry. For wet etching please see below on this page. Dry etching can be done either with ICP using Chlorine chemistry or with IBE by sputtering with Ar ions.

Wet etching of Chromium

Fume hood: positioned in cleanroom 2.
Wet Etch of Chromium can take place in a beaker in this fume hood

Wet etching of chromium at Danchip is done making your own set up in a beaker in a fume hood - preferably in cleanroom 2 or 4. We have two solution for this:

  1. HNO3:H2O:cerisulphate - 90ml:1200ml:15g - standard at Danchip
  2. Commercial chromium etch

Etch rate are depending on the level of oxidation of the metal.

How to mix the Chromium etch 1:

  1. Take a beaker and add 15g of cerisulphate.
  2. Add a little water while stirring - make sure all lumps are gone.
  3. Add water until 600 ml - keep stirring (use magnetic stirring)
  4. Add 90 ml HNO3
  5. When the cerisulphate is completely dissolved (clear liquid) you can add the other 600 ml of wafer.



Overview of the data for the chromium etches

Chromium etch 1 Chromium etch 2
General description

Etch of chromium

Etch of chromium

Chemical solution HNO3:H2O:cerisulphate - 90ml:1200ml:15g .
Process temperature Room temperature .
Possible masking materials

Photoresist (1.5 µm AZ5214E)

.

Etch rate

~40-100 nm/min

.

Batch size

1-25 wafers at a time

.

Size of substrate

4" wafers

.

Allowed materials

No restrictions. Make a note on the bottle of which materials have been processed.

.

Dry etching of chromium

On the ICP Metal Etch tool a recipe for chromium is being developed.