In case one have the used single crystal substrate and the film is removed by etching, now what kind of defects and impurities will be present at the substrate surface, and is the crystal planes of the substrate also affected by any kind of etching?
If yes how to confirm it experimentally?
Of course there is a huge influence of the etching method. There are thousands of works for different substrate types, but the general trends would be:
1) Non-reactive dry etching is the most anisotropic, but also non-selective method. That means that the etching process only takes place in the direction from which your etching plasma ions are coming. The crystal facet is generally less relevant here.
2) Reactive methods, especially wet etching, may be isotropic, but also selective. That means that in principle all sides, not just the "incoming flow" direction will be affected, but a more stable surface with a lower surface energy will probably be etched more slowly. See e.g.
Article Anisotropy in the wet-etching of semiconductors
Thank you Jürgen Weippert for your reply. could you please tell me that in the case of dry etching, is the binding energy of atoms of the substrate also decide the etching rate?
you just have to imagine interplay between binding energy and energy transfer in etching process.....dry etching mostly ....external energetic atoms, ions are colliding and removing surface atoms...so here difference of energy increases then no effect of binding energy of surface atoms of substrate...in the wet etching chemical reactions are involved...hence breaking bonds or displacement reactions will be more selective and acts effectively at active sites....so non uniformity will be there...but is substrate surface is uniform and stable, then it does not make difference there also.
Of course, etching rates depend on the substance and etching processes need to be optimized for every material. The binding energy is only one of several factors, the material's conductivity or dielectric function also play a role since they affect the plasma shape. In my own experiments, I tried a recipe which was designed to softetch 1nm of SiO2 per minute; on my sputtered metal oxide films it resulted in an etching rate of 0.3nm/min.
Dear Jignesh G. Hirpara and Jürgen Weippert thank you for your answers. My quarry is regarding the surface atoms of substrate, suppose our substrate is oxide as LAO, MgO, STO, etc, then the binding energy is different for different atoms at the surface also. In this case, the etching rate will be the same as Jürgen Weippert also suggests that other factors will also affect it.
How do you come from our answers to the statement that "the etching rate will be the same"? That's exactly the opposite of what we wrote.
I have mistakenly mixed two lines. I am also assuming that the etching rate is different.
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