Pattern transfer

The main task of etching is the removal of material from a substrate at selected locations up to a specified depth, while leaving the remainder of the substrate unchanged.
Usually the etch locations are defined by a masking layer which is removed after etching.
Often the materials to be etched are present as thin films deposited onto the substrate, and include metals, oxides, nitrides, etc.
Common substrates are made of silicon (wafers), glass, or ceramics.

The available techniques include wet-chemical etching employing liquids and dry etching, employing plasmas inside vacuum systems.
For every task one has to weigh the pros and cons of both techniques and make the best choice.
A wet etch, if possible, usually proceeds in a (more or less) isotropic way, that is without (much) directionality, and is therefore accompanied by mask undercut.
In general, dry etching is the obvious choice when the smallest mask details (critical dimensions) are around or below 1µm.
Or when etch directionality is an important issue, with the vertical etch as the ultimate limit to obtain 1:1 transfer of structures from the mask into the substrate surface.
Dry etching tools are available at MiPlaza Thin Film Processing.

Wet-chemical etching

Wet etching is a relatively simple method to structure thin films and bulk materials.
For this it is combined with photolithographic techniques for masking the areas which are not to be etched. It is based on the dissolution of the material in an appropriate etchant.
Within Device Processing wet etching techniques are widely applied because they are flexible, easy, robust etc.


The following etch baths of importance for our daily applications are available for substrates upto 150 x 150 mm:

  • Metal etchants:
    Cr, Al, Mo
  • Oxide etchants:
    ITO, SiO2, Al2O3 and glasses

For other materials either we make use of a general purpose fume cabinet or we make use of the Thin Film Processing facilities.
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